College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
UNIVERSITY OF MINDANAO
College of Engineering Education
Civil Engineering Program
Physically Distanced but Academically Engaged
Self-Instructional Manual (SIM) for
Self-Directed Learning (SDL)
Course/Subject: : BCE 223/L – CONSTRUCTION MATERIALS
AND TESTING
Name of Teacher: Engr. Jose S. Condonar Jr.
THIS SIM/SDL MANUAL IS A DRAFT VERSION ONLY; NOT FOR REPRODUCTION AND
DISTRIBUTION OUTSIDE OF ITS INTENDED USE. THIS IS INTENDED ONLY FOR THE
USE OF THE STUDENTS WHO ARE OFFICIALLY ENROLLED IN THE COURSE/SUBJECT.
EXPECT REVISIONS OF THE MANUAL.
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College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
TABLE OF CONTENTS
PAGE
Cover Page …………………………………………………………………………………………………
Table of Contents………………………………………………………………………………………..
Course Outline……………………………………………………………………………………………
Course Outline Policy………………………………………………………………………………….
Course Information…………………………………………………………………………………….
1
2
4
4
6
Topic/ Activity
Unit Learning Outcomes- Unit 1
Big Picture in Focus: ULO-1a…………………………………………………………………..…..
7
Metalanguage…………………………………………………………………………………... 7
Essential Knowledge………………………………………………………………………… 7
INTRODUCTION: Building Stones, Structural Clay and Aggregates
1. Types and Properties of Building Stones, Structural Clay …... 8
2. Aggregates ……………………………………………………………………….. 15
3. Reducing Field Sample of Aggregates to Testing Size …………. 15
4. Determination of Surface Moisture of Coarse Aggregates …….. 18
5. Sieve Analysis of Coarse Aggregates …………………………………… 20
6. Determination of Unit Weight of Aggregates ……………………….. 25
7. Specific Gravity Determination – FA & C ……………………………… 26
8. Absorption Determination- FA & CA ……………………………………. 26
9. Unit Weight Determination- FA & CA ………………………………….. 32
10. Moisture Content Determination- FA & CA …………………………. 37
11. Determination of Fineness Modulus ……………………………………. 39
12. Soundness Test ………………………………………………………………….. 43
13. Test for Organic Impurities ………………………………………………….. 47
14. Abrasion Test …………………………………………………………………….. 50
SELF HELP ………………………………………………………………………………………. 53
Let’s Check ……………………………………………………………………………………..
53
Let’s Analyze ………………………………………………………………………………….
54.
In a Nutshell …………………………………………………………………………………..
54
Q & A Lists ……………………………………………………………………………………..
55
Keyword Index ……………………………………………………………………………..
56
Unit Learning Outcomes – Unit 2
Big Picture in Focus: ULO-2a…………………………………………………………………..…..
Metalanguage…………………………………………………………………………………...
Essential Knowledge…………………………………………………………………………
INTODUCTION : Cement and Concrete
1.
2.
3.
4.
5.
6.
Types of Cement Used in Construction ……………………………………….
Hydraulic Cement by Vicat Needle……………………………………………….
Common Concrete Mix Proportion and Its Application………………….
Portland and Hydraulic Cement Concrete ……………………………………
Admixtures ……………………………………………………….……………………..
Completed Pavement ………………………………………………………………….
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College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
SELF HELP ………………………………………………………………………………………
Let’s Check ……………………………………………………………………………………..
Let’s Analyze ………………………………………………………………………………….
In a Nutshell …………………………………………………………………………………..
Q & A Lists ……………………………………………………………………………………..
Keyword Index ……………………………………………………………………………..
Unit Learning Outcomes- Unit 3
Big Picture in Focus: ULO-3a…………………………………………………………………..…..
Metalanguage…………………………………………………………………………………...
Essential Knowledge…………………………………………………………………………
INTRODUCTION: Metals and Woods
1. Metals: Wrought Iron, Cast Iron, Steel and Alloys ….……………
2. Quality Test for Bending, Tension and Chemical Analysis ……
3. Reinforcing Steel……………………………………………………………….
4. Markings ………………………………..…………………………………………
5. Basic Properties ………………………………………………………………..
6. Tensile Test ……………… …………………………………………………….
7. Wood: Characteristics and It’s Physical Properties …………….
8. Testing Requirements ……………………………………………………….
SELF HELP ……………………………………………………………………………………..
Let’s Check ……………………………………………………………………………………..
Let’s Analyze ………………………………………………………………………………….
In a Nutshell …………………………………………………………………………………..
Q & A Lists ……………………………………………………………………………………..
Keyword Index ……………………………………………………………………………..
Unit Learning Outcomes- Unit 4
Big Picture in Focus: ULO-1a…………………………………………………………………..…..
Metalanguage…………………………………………………………………………………...
Essential Knowledge…………………………………………………………………………
INTRODUCTION: Asphalts
1. Bituminous Materials ………..………………………………………………
2. Composition of Asphalts…………………………………………………….
3. Kinds and Uses of Asphalt …………………………………………………
4. Quality of Bituminous Materials Used in Different
Mixtures/Surfaces …………………………………………………………….
5. Bituminous Mixing Plants ………………………………………………….
6. Laboratory Tests for Bituminous Materials ………………………..
SELF HELP ………………………………………………………………………………………
Let’s Check ……………………………………………………………………………………..
Let’s Analyze ……………………………………………………………………………….….
In a Nutshell …………………………………………………………………………………...
Q & A Lists ……………………………………………………………………………………...
Keyword Index ………………………………………………………………………………
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College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
COURSE OUTLINE: CE 435/L – CONSTRUCTION MATERIALS AND TESTING
Course Coordinator:
Email:
Student Consultation:
Mobile:
Phone:
Effectivity Date:
Mode of Delivery:
Time Frame:
Student Workload:
Requisites:
Co- requisite:
Credit:
Attendance Requirements:
Virtual
Engr. Jose S. Condonar Jr.
jcondonarjr@umindanao.edu.ph/joconjr@yahoo.com
Through LMS BB, e-mail, messenger or by phone
09092363587
(082) 2961084 or local 131 Office
May 25, 2020
Blended (On-Line with face to face or virtual sessions)
36 Hours lecture and 54 Hours laboratory
Expected Self-Directed Learning
CEE 117
BCE 222
2 units lecture, 1unit laboratory
A minimum of 95% attendance is required at all scheduled
or face to face sessions.
COURSE OUTLINE POLICY
Areas of Concern
Contact and Non-contact Hours
Assessment Task Submission
Details
This 2-unit and 1-unit laboratory course selfinstructional manual is designed for blended learning
mode of instructional delivery with scheduled face to
face or virtual sessions. The expected number of hours
will be 36 hours lecture and 54 hours laboratory
including the face to face or virtual sessions. The
expected number of hours will be 90 including the
face-to-face or virtual sessions. The face-to-face
sessions shall include the summative assessment tasks
(exams) since this course is crucial in the licensure
examination for civil engineers.
Submission of assessment tasks shall be on 3rd, 5th, 7th
and 9th week of the term. The assessment paper shall
be attached with a cover page indicating the title of the
assessment task (if the task is performance), the
name of the course coordinator, date of submission
and name of the student. The document should be
emailed to the course coordinator. It is also expected
that you already paid your tuition and other fees
before the submission of the assessment task.
If the assessment task is done in real time through the
features in the Blackboard Learning Management
System, the schedule shall be arranged ahead of time
by the course coordinator.
Since this course is included in the licensure
examination for civil engineers, you will be required to
take the exam inside the University. This should be
scheduled ahead of time by your course coordinator.
Page 4 of 227
College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
Turnitin Submission
(if necessary)
Penalties for Late
Assignments/Assessments
Return of Assignments/
Assessments
Assignment Resubmission
Re-marking of Assessment
Papers and Appeal
This is non-negotiable for all licensure-based
programs.
To ensure honesty and authenticity, all assessment
tasks are required to be submitted through Turnitin
with a maximum similarity index of 30% allowed. This
means that if your paper goes beyond 30%, the
students will either opt to redo her/his paper or
explain in writing addressed to the course coordinator
the reasons for the similarity. In addition, if the paper
has reached more than 30% similarity index, the
student may be called for a disciplinary action in
accordance with the University’s OPM on Intellectual
and Academic Honesty.
Please note that academic dishonesty such as cheating
and commissioning other students or people to
complete the task for you have severe punishments
(reprimand, warning, expulsion).
The score for an assessment item submitted after the
designated time on the due date, without an approved
extension of time, will be reduced by 5% of the
possible maximum score for that assessment item for
each day or part day that the assessment item is late.
However, if the late submission of assessment paper
has a valid reason, a letter of explanation should be
submitted and approved by the course coordinator. If
necessary, you will also be required to present/attach
evidences.
Assessment tasks will be returned to you two (2)
weeks
after the submission. This will be returned by email or
via Blackboard portal.
For group assessment tasks, the course coordinator
will require some or few of the students for online or
virtual sessions to ask clarificatory questions to
validate the originality of the assessment task
submitted and to ensure that all the group members
are involved.
You should request in writing addressed to the course
coordinator his/her intention to resubmit an
assessment task. The resubmission is premised on the
student’s failure to comply with the similarity index
and other reasonable grounds such as academic
literacy standards or other reasonable circumstances
e.g.
illness, accidents financial constraints.
You should request in writing addressed to the
program
coordinator your intention to appeal or contest the
score given to an assessment task. The letter should
explicitly explain the reasons/points to contest the
Page 5 of 227
College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
grade. The program coordinator shall communicate
with the students on the approval and disapproval of
the
request.
Grading System
If disapproved by the course coordinator, you can
elevate your case to the program head or the dean
with
the original letter of request. The final decision will
come from the dean of the college.
All culled from BlackBoard sessions and traditional
contact
Course discussions/exercises – 30%
1st formative assessment – 10%
2nd formative assessment – 10%
3rd formative assessment – 10%
All culled from on-campus/onsite sessions (TBA):
Final exam – 40%
Preferred Referencing Style
Student Communication
Submission of the final grades shall follow the usual
University system and procedures.
Depends on the discipline; if uncertain or inadequate,
use the general practice of the APA 6th Edition.
You are required to create a umindanao email account
which is a requirement to access the BlackBoard
portal.
Then, the course coordinator shall enroll the
students to have access to the materials and resources
of the course. All communication formats: chat,
submission of assessment tasks, requests etc. shall be
through the portal and other university recognized
platforms.
You can also meet the course coordinator in person
through the scheduled face to face sessions to raise
your issues and concerns.
For students who have not created their student email,
please contact the course coordinator or program
head.
Contact Details of the Dean
Dr. Charlito L. Cañesares
Email: clcanesares@umindanao.edu.ph
Phone: (082) 296-1084 or 300-5456 loc. 133
Contact Details of the Program
Head
Students with Special Needs
Engr. Showna Lee T. Sales
Email: ssales@umindanao.edu.ph
Phone: (082) 296-1084 or 300-5456 loc. 133
Students with special needs shall communicate with
the course coordinator about the nature of his or her
special needs. Depending on the nature of the need,
the course coordinator with the approval of the
program coordinator may provide alternative
assessment tasks or extension of the deadline of
Page 6 of 227
College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
submission of assessment tasks. However, the
alternative assessment tasks should still be in the
service of achieving the desired course learning
outcomes.
Help Desk Co0ntact
CEE BLACKBOARD
ADMINISTRATOR
CEE
Library Contact
GSTC Contact
Jetron J. Adtoon
jadtoon@umindanao.edu.ph
09055267834
Frida Santa O. Dagatan
cee@umindanao.edu.ph
09562082442
082-2272902
Brigida E. Bacani
library@umindanao.edu.ph
09513766681
Ronadora E. Deala, RPsy, RPm, RGC, LPT
ronadora_deala@umindanao.edu.ph
09212122846
Silvino P. Josol
gstcmain@umindanao.edu.ph
0906075772
Course Information – see/download course syllabus in the Blackboard LMS
CC’s Voice:
Hello prospective engineers! Welcome to this course CE 435L: Construction
Materials and Testing. By now, I am confident that you really wanted to become
a civil engineer and that you have visualized yourself with professional expertise
and ethical responsibility in the practice of the profession. Furthermore, show
dedication and initiative in research and innovation or entrepreneurial ventures,
and professional development.
CO:
Upon completion of this course, you are expected to:
CO1. Recognize the physical and structural properties for most common and
advanced construction materials
CO 2. Conduct experiments on common construction materials according to
international standards such as the American Society for Testing and Materials
(ASTM)
CO 3. Evaluate the results of the test of common construction material
Let us begin!
BIG PICTURE
Week 1 to 3: Unit Learning Outcomes 1 (ULO 1): At the end of the unit, you are
expected to:
a. Demonstrate knowledge and understanding of the properties and behaviors
of most common and advance construction material such as building stones,
structural clay and aggregates.
Page 7 of 227
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2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
b. Conduct the methods, procedures and formulas of different experiments on
common construction materials according to international standards such as
ASTM & AASTHO.
Big Picture in
Focus
ULO
1a. Demonstrate knowledge and understanding of the properties and
behaviors of most common and advance construction material such as building
stones, structural clay and aggregates
Metalanguage
This section deals with the study of different types and properties of construction
materials such as building stones, structural clay and aggregates.
Please proceed immediately to the “Essential Knowledge”.
Essential Knowledge
To perform the aforesaid big picture (unit learning outcomes) for the first three (3) weeks
of the course, you need to fully understand the following essential knowledge that will be
laid down in the succeeding pages. Please note that you are not limited to exclusively refer
to these resources. Thus, you are expected to utilize other books, research articles and
other resources that are available in the university’s library e.g. ebrary,
search.proquest.com etc.
INTRODUCTION
Building material is any material which is used for construction purposes. This can be
classified as natural or synthetic. Many naturally occurring substances such as rocks, clay,
sand and wood , even twigs and leaves, have been used for construction. Apart from
naturally occurring materials, many man-made products are in use, some more and some
less synthetic. The manufacturing of building materials is an established industry in many
countries and the use of these materials is typically segmented into specific specialty
trades, such as carpentry, insulation, plumbing, and roofing work.
TYPES AND PROPERTIES OF BUILDING STONES & STRUCTURAL CLAY
I.
Building Stones
Stones are naturally occurring compact, solid and massive material that make the
crust of the earth. Technically, the stones are called as rocks. The rocks occur in
great variety. The rocks possess suitable properties often find use in building
stones. It follows that all building stones are rocks in nature, all rocks may not be
useful as building stones.
➢ Classification of Stones
A. Geological Classification
This classification is based on mode of formation of the rock from which
building stones are obtained. Three main group recognized are:
Page 8 of 227
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Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
I)
Igneous Rocks - those rocks of the earth that have been formed by
the natural process of cooling and crystallization from originally hot
and molten magma. Granite, Gabbro, Basalt, Diorite and
Obsidian are some of the examples of Igneous Rocks.
II)
Sedimentary Rocks - are formed from any type of preexisting
rocks by a simple process of breakdown into smaller particles under
the influence of natural agencies like wind, water and ice and
atmospheric gases. This type of rocks includes Conglomerate,
Sandstone, Siltstone, Shale, etc.
III)
Metamorphic Rocks - These are originally either igneous or
sedimentary rocks. The process for their change under the influence
of increased temperature, pressure, and chemical environment is
called metamorphism. The most well-known examples of
metamorphic rocks are marble and slate.
B. Physical Classification
The basis for such a classification is the physical properties of rocks, the
manner and arrangement of different particles and mass forming a stone.
They classified as follows:
I)
Foliated Rocks - show definite parallel arrangement of minerals
showing a tendency to split in a specific direction. Examples are
gneiss, and schist.
II)
Stratified Rocks - formed due to the splitting of parallel layers of
sedimentary rocks. They exhibit distinct layers which can be
separated. The plane of separation is called as a cleavage plane.
Examples are limestone, slate, and sandstone.
III)
Unstratified Rocks - are granular or crystalline structure and
become solid and cooling. They do not show any sign of strata.
Examples are igneous rocks like granite, basalt, etc.
C. Chemical Classification
The presence of chemical constituents in the rocks is the basis for their type
of classification. they are as follows:
I)
Argillaceous Rocks - clay and alumina is the main constituents.
Examples of the argillaceous rocks are slate, laterite, etc.
II)
Siliceous Rocks - in this type, silica is the main constituent. The
presence of the silica in the free state is called sand, and in the
combined state is silicate. Examples of the silicate rocks are
sandstone, quartzite, etc.
III)
Calcareous Rocks - calcium carbonate or lime is the main
constituents in these rocks. They are readily acted upon by dilute
HCL. Examples are limestone, marble, etc.
II.
Structural Clay
Page 9 of 227
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Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
Structural Clay is a widely used material in the construction Industry. It is a
recyclable and sustainable product, it is fire resistant and the color ranges from
light brown to burnt red. The various types of clay products used in the
construction industry are:
1. Brick – is extensively used in the construction of the external and internal walls
of the building where they are joined with cement plaster.
2. Terracotta – is used as a roofing material and external natural tile cladding
material to create the feel of exposed brick work.
3. Hollow Block Tile – are used to create the external walls of the building and
are very good insulators of sound and heat.
4. Paver Blocks – are used in driveways and landscaped gardens. They are light
in weight, strong and are usually in the form of interlocking tiles.
5. Brick Glazed Tile – Glazed brick tiles are used as an external cladding material
so as to give the look of exposed brick work.
6. Roofing Material – Clay is used as roofing material in many houses having
sloped roofs. This prevents the entry of water into the interiors. It is mainly
used in areas having heavy rainfall.
III.
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Properties of Building Materials
A. Physical Properties
These are the properties required to estimate the quality and condition of the
material without any external force. The physical properties of engineering
materials are as follows:
Bulk Density is the ratio of mass to the volume of the material in its natural state
that is including voids and pores. It is expressed in kg/m3. Bulk density influences
the mechanical properties of materials like strength, heat and conductivity etc.
Porosity gives the volume of the material occupied by pores. It is the ratio of
volume of pores to the volume of material. Porosity influences many properties
like thermal conductivity, strength, bulk density, durability etc.
Durability is the property of a material to withstand against the combined action
of atmospheric and other factors. If the material is more durable, it will be useful
for longer life. Maintenance cost of material is dependent of durability.
Specific Gravity is the ratio of mass of given substance to the mass of water at 4oC
for the equal volumes.
Fire resistance is the ability to withstand against fire without changing its shape
and other properties. Fire resistance of a material is tested by the combined
actions of water and fire. Fireproof materials should provide more safety in case
of fire.
Frost resistance is the ability of a material to resist freezing or thawing. It
depends upon the density and bulk density of material. Denser materials will have
more frost resistance. Moist materials have low frost resistance and they lose their
strength in freezing and become brittle.
Page 10 of 227
College of Engineering Education
2nd Floor, B&E Building
Matina Campus, Davao City
Telefax: (082) 296-1084
Phone No.: (082)300-5456/300-0647 Local 133
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Weathering Resistance is the property of a material to withstand against all
atmospheric actions without losing its strength and shape. Weathering effects the
durability of material. For example, corrosion occurs in iron due to weathering. To
resist this paint layer is provided.
Spalling Resistance is the ability of a material to undergo certain number of
cycles of sharp temperature variations without failing. It is the dependent of
coefficient of linear expansion.
Water Absorption is the capacity of a material to absorb and retain water in it. It
is expressed in % of weight of dry material. It depends up on the size, shape and
number of pores of material.
Water Permeability is the ability of a material to permit water through it.
Hygroscopicity is the property of a material to absorb water vapor from the air.
It depends on the relative humidity, porosity, air temperature etc.
Refractoriness is the property of a material which cannot melts or lose its shape
at prolonged high temperatures (1580oC or more). Example: fire clay is high
refractory material.
B. Mechanical Properties
Mechanical properties of the materials are find out by applying external forces on
them. The mechanical properties are,
Strength is the capacity of a material to resist failure caused by loads acting on it.
The load may be compressive, tensile or bending. It is determined by dividing the
ultimate load taken by the material with its cross sectional area.
Hardness is the property of a material to resist scratching by a herder body. MOHS
scale is used to determine the hardness of a materials.
Elasticity is the capacity of a material to regain its initial shape and size after
removal of load is known as elasticity and the material is called as elastic material.
Plasticity is when the load applied on the material will undergo permanent
deformation without cracking and retain this shape after the removal of load then
it is said to be plastic material.
Brittleness is when the material subjected to load, fails suddenly without causing
any deformation then it is called brittle material.
Fatigue. If a material is subjected to repeated loads, then the failure occurs at
some point which is lower than the failure point caused by steady loads.
Impact Strength. If a material is subjected to sudden loads and it will undergo
some deformation without causing rupture. It designates the toughness of
material.
Abrasion Resistance. The loss of material due to rubbing of particles while
working is called abrasion. The abrasion resistance for a material makes it durable
and provided long life.
Creep is the deformation caused by constant loads for long periods.
C. Chemical Properties
Page 11 of 227
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•
•
The properties of materials against the chemical actions or chemical
combinations are termed as chemical properties. And they are,
Chemical Resistance is the ability of a construction material to resist the effects
of chemicals like acids, salts and alkalis.
Corrosion Resistance. Formation of rust (iron oxide) in metals, when they are
subjected to atmosphere is called as corrosion.
D. Thermal Properties
The thermal properties of a material are those that are related to the materials
response to heat. When a material is subjected to a change in temperature, it may
expand, contract, conduct, or reflect heat. Ceramics can withstand high
temperatures, are good thermal insulators, and do not expand greatly
when heated.
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IV.
Thermal Capacity is the property of a material to absorb heat and it is required
to design proper ventilation. It influences the thermal stability of walls. It is
expressed in J/NC and it is calculated by the formula:
Thermal capacity, T = [H/(M(T2 – T1))]
Where H = quantity of heat required to increase the temperature from T1 to T2
T1 = Initial temperature
T2 = Final temperature
M = Mass of material in N.
Thermal Conductivity. The amount of heat transferred through unit area of
specimen with unit thickness in unit time is termed as thermal conductivity.
Thermal Resistivity. It is the ability to resist heat conduction. And it is the
reciprocal of thermal conductivity. When it is multiplied by thickness of material
it gives thermal resistance.
Specific Heat is the quantity of heat required to heat 1 N of material by 1C. Specific
heat is useful when we use the material in high temperature areas.
AGGREGATES
Aggregate, in building and construction, is a material used for mixing with
cement, bitumen, lime, gypsum, or other adhesive to form concrete or mortar. The
aggregate gives volume, stability, resistance to wear or erosion, and other desired
physical properties to the finished product. Commonly used aggregates include sand,
crushed or broken stone, gravel (pebbles), broken blast-furnace slag, boiler ashes
(clinkers), burned shale, and burned clay. Fine aggregate usually consists of sand,
crushed stone, or crushed slag screenings; coarse aggregate consists of gravel
(pebbles), fragments of broken stone, slag, and other coarse substances. Fine
aggregate is used in making thin concrete slabs or other structural members and
where a smooth surface is desired; coarse aggregate is used for more massive
members.
V.
PROPERTIES OF AGGREATES
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1. Composition. Aggregates consisting of materials that can react with alkalis in
cement and cause excessive expansion, cracking and deterioration of concrete mix
should never be used. Therefore, it is required to test aggregates to know whether
there is presence of any such constituents in aggregate or not.
2. Size & Shape. The size and shape of the aggregate particles greatly influence the
quantity of cement required in concrete mix and hence ultimately economy of
concrete.
3. Surface Texture. The development of hard bond strength between aggregate
particles and cement paste depends upon the surface texture, surface roughness
and surface porosity of the aggregate particles. If the surface is rough but porous,
maximum bond strength develops.
4. Specific Gravity. The ratio of weight of oven dried aggregates maintained for 24
hours at a temperature of 100 to 110 C, to the weight of equal volume of water
displaced by saturated dry surface aggregate is known as specific gravity of
aggregates.
5. Bulk Density. It is defined as the weight of the aggregate required to fill a
container of unit volume. It is generally expressed in kg/litre.
6. Voids. The empty spaces between the aggregate particles are known as voids. The
volume of void equals the difference between the gross volume of the aggregate
mass and the volume occupied by the particles alone.
7. Porosity & Absorption. The minute holes formed in rocks during solidification of
the molten magma, due to air bubbles, are known as pores. Rocks containing pores
are called porous rocks. Water absorption may be defined as the difference
between the weight of very dry aggregates and the weight of the saturated
aggregates with surface dry conditions.
8. Fineness Modulus. Fineness modulus is generally used to get an idea of how
coarse or fine the aggregate is. More fineness modulus value indicates that the
aggregate is coarser and small value of fineness modulus indicates that the
aggregate is finer.
9. Deleterious Materials. Aggregates should not contain any harmful material in
such a quantity so as to affect the strength and durability of the concrete.
10. Crushing Value. The aggregates crushing value gives a relative measure of
resistance of an aggregate to crushing under gradually applied compressive load.
11. Impact Value. The aggregate impact value gives a relative measure of the
resistance of an aggregate to sudden shock or impact.
12. Abrasion value of aggregates. The abrasion value gives a relative measure of
resistance of an aggregate to wear when it is rotated in a cylinder along with some
abrasive charge.
What is ASTM?
ASTM was originally known as the American Society of the International
Association for Testing and Materials when it was created in 1898 by
Pennsylvania Railroad engineers and scientists. Its purpose was to address and
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prevent the frequent rail breaks that were plaguing the industry by developing
standards that would ensure higher quality rail products.
Today, the American Society for Testing and Materials is known as ASTM
International. It consists of over 30,000 members that include product users,
producers, consumers, academics, and consultants. ASTM is still headquartered in
Pennsylvania, but it also has offices throughout the world that are located in
Belgium, Canada, China, and Mexico, as well as one other domestic office in
Washington DC.
ASTM has come a long way from creating standards for steel in the railroad industry.
Today, ASTM develops and publishes technical standards for many different
industries with the goal of enhancing performance and safety over a wide range of
products, materials, systems, and services. Thousands of ASTM standards are
upheld all over the world, each with their own unique number. Each standard falls
into a variety of categories which include:
•
•
•
•
•
Standard Specification
Standard Test Method
Standard Practice Guide
Standard Classification
Terminology Standard
Not only does ASTM create dependable standards, the society also offers
technical training programs, proficiency testing, and inter-laboratory crosscheck
programs.
Continuing education and online training programs are available for industries and
government employees. Courses can include plastics, coal, statistics, glass, and
more. Self-guided training courses are available for QA/QC technicians who work
with cement, concrete strength training, and who conduct aggregate testing. On-site
training is also available, as are certification programs that cover a wide variety of
products, materials, systems, and services in keeping with third party compliance
standards.
This is a list of ASTM International standards. Standard designations usually
consist of a letter prefix and a sequentially assigned number. This may optionally be
followed by a dash and the last two digits of the year in which the standard was
adopted. Prefix letters correspond to the following subjects:
•
•
•
•
•
•
•
A = Iron and Steel Materials
B = Nonferrous Metal Materials
C = Ceramic, Concrete, and Masonry Materials
D = Miscellaneous Materials
E = Miscellaneous Subjects
F = Materials for Specific Applications
G = Corrosion, Deterioration, and Degradation of Materials
This list may include either current or withdrawn standards. A withdrawn standard
has been discontinued by its sponsoring committee. A standard may be withdrawn
with or without replacement.
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What is AASHTO?
The American Association of State Highway and Transportation Officials
(AASHTO) is a nonprofit, nonpartisan association representing highway and
transportation departments in the 50 states, the District of Columbia, and Puerto
Rico. It represents all transportation modes including: air, highways, public
transportation, active transportation, rail, and water. Its primary goal is to foster
the development, operation, and maintenance of an integrated national
transportation system.
AASHTO works to educate the public and key decision makers about the critical role
that transportation plays in securing a good quality of life and sound economy for
our nation. AASHTO serves as a liaison between state departments of transportation
and the Federal government. AASHTO is an international leader in setting technical
standards for all phases of highway system development. Standards are issued for
design, construction of highways and bridges, materials, and many other technical
areas.
AASHTO serves as a catalyst for excellence in transportation by offering:
1. Smart solutions and promising practices;
2. Critical information, training and data;
3. Direct technical assistance to states; and
4. Unchallenged expertise.
AASHTO is guided by a Board of Directors made up of the chief transportation
officers from the 50 states, the District of Columbia, and Puerto Rico. The 12member Executive Committee is led by AASHTO’s elected officers, and is assisted by
its executive director.
AASHTO’s policy development, standards setting, and technical activities are the
product of volunteer state department of transportation personnel who work
through the AASHTO committee structure. The committees collaborate throughout
the year and typically meet annually. These committees, which represent the
highest standard of transportation expertise in the country, address virtually every
element of planning, designing, constructing, and maintaining transportation
services.
STANDARD PRACTICE FOR REDUCING SAMPLES OF AGGREGATE TO TESTING
SIZE
REFERENCED STANDARD: ASTM C702-87 / AASHTO T248-89
The field samples of aggregate must generally be reduced to an appropriate
size for testing to determine physical characteristics, such as, sieve analysis,
soundness, hardness, etc. The methods described in this test method are intended
to minimize variations in the aggregate characteristics between the smaller test
sample and the larger field sample.
Several methods of sample reduction will be described. The technician must
be sure to use the appropriate technique dependent on such factors as aggregate
size and moisture content.
The reduction methods include:
Method A - Mechanical Splitter
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Method B - Miniature Stockpile
Method C - Quartering
In some circumstances, reducing the field sample prior to testing is not
recommended. Substantial differences may unavoidably occur during sample
reduction, i.e., in the case of an aggregate having relatively few large size particles
in the sample. These few particles may be unequally distributed among the reduced
size test samples. If the test sample is being examined for certain contaminants
occurring as a few discreet particles in a small percentage, the reduced test sample
may not be truly representative of the total aggregate as produced. In these cases,
the entire original field sample should be tested.
Failure to carefully follow the procedures in these methods of sample
reduction may result in providing a nonrepresentative sample for subsequent
testing, resulting in inaccurate test results, and ultimately, failure of the aggregate
to perform as intended.
SUMMARY OF PROCEDURE
Aggregate and other materials sampled in the field need to be reduced to
appropriate sizes for testing. It is, therefore, necessary to reduce field samples while
minimizing the chance of variability during handling. In some instances, a few
particles on a given sieve might affect a gradation significantly enough to alter an
interpretation of the field sample and subsequently the entire material's compliance
with specifications.
The appropriate field sample reduction method is dependent chiefly on the
nominal maximum size of the aggregate, the amount of free moisture in the sample,
and the equipment available.
The following chart should be used in selecting the appropriate reduction
method for the aggregate to be tested.
METHOD A -- MECHANICAL SPLITTER
Apparatus
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Mechanical Splitter - The mechanical sample splitter shall have an even
number of equal width chutes, not less than eight for coarse or combined aggregate,
or twelve for fine aggregate. The chutes shall discharge alternately to each side of
the splitter. For coarse and combined aggregates, the width of the individual chutes
shall be approximately twice the largest size particle in the sample to be reduced.
For dry fine aggregate in which the entire sample will pass the 3/8 in. (9.5 mm)
sieve, the minimum width of the chutes shall be at least fifty percent larger than the
largest particles in the sample with a maximum width of 3/4 in. (20 mm).
The splitter shall be equipped with at least two receptacles (catch pans) to
hold the two halves of the sample during splitting. It shall also be equipped with a
hopper or straight-edge pan with a width equal to or slightly less than the overall
width of the assembly of chutes, by which the sample may be fed at a controlled rate
into the chutes.
The splitter and accessories shall be designed to allow the sample to flow
smoothly without restriction or loss of material.
Mechanical splitters are commonly available in sizes adequate for aggregate
having the largest particle size not over 1 1/2 in. (37.5 mm).
Procedure
1. Place the original sample, or portion thereof, in the hopper or pan and uniformly
distribute it from edge to edge being sure the sample appears homogenous (wellblended). Carefully introduce the sample into the chutes in a manner to allow the
aggregate to flow freely through the openings and into the catch pans. Continue
this procedure until the entire sample has been halved, being careful that catch
pans do not overflow.
2. Remove the catch pans and set aside. Continue splitting one half of the material.
Follow this procedure, being sure to split entire increments, until the desired test
sample size is obtained. Retain the unused material until all desired tests are
performed in case a retest is needed.
Note: Sometimes a significant amount of fines may be lost in the splitting process if the
sample is extremely dry and the action of pouring the sample through the splitter
chutes creates a large dust cloud, suspending the fines in the air above the splitter.
If this is a serious concern, then add a small amount of water to the original sample
and mix thoroughly before splitting the sample. The extra moisture will prevent
many of the fines from becoming suspended in the air and drifting off. Remember
to not add so much water that the moisture content ends up being at or greater than
the SSD condition, in which case the mechanical splitting method would no longer
be valid. In any case, be sure to perform the splitting procedure in a well-ventilated
area while wearing a suitable dust mask.
METHOD B -- MINIATURE STOCKPILE
Apparatus
Straight-edge scoop
Shovel or trowel (for mixing the aggregate)
Small sampling thief, small scoop, or spoon
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Procedure
This method is for damp, fine aggregate only.
1. Place the field sample on a hard, clean, level surface where there will be no loss of
material or contamination. Mix the sample by turning the entire sample over three
times with a shovel. With the last turning, shovel the entire sample into a conical
pile by depositing each shovelful on top of the preceding one.
2. Obtain a sample for each test to be performed by selecting at least five increments
of material at random locations from the miniature stockpile using a sample thief,
small scoop, or spoon.
METHOD C -- QUARTERING
Apparatus
Straight-edged scoop
Flat-edged shovel or trowel
Broom or brush
Alternate method only - canvas blanket measuring approximately 6 ft. x 8 ft (2 m by 2.5
m).
Procedure
1. Place the original sample on a hard, clean, level surface. Mix the material
thoroughly by turning the entire sample over with the shovel at least three times.
With the last turning, shovel the entire sample into a conical pile by depositing
each shovelful on top of the preceding one. Carefully flatten the conical pile to a
uniform thickness and diameter by pressing down the apex with the shovel so that
each quarter section of the resulting pile will contain the material originally in the
pile. The pile diameter should be approximately four to eight times the thickness.
2. Divide the flattened pile into four equal quarters with the shovel or trowel.
Remove two diagonally opposite quarters, including all fine material. Brush the
cleared spaces clean. Successively mix and quarter the remaining material in the
same fashion as the original sample. Continue this process until the desired
quantity is obtained.
Save the unused portion of the original field sample until all testing is
completed in case a retest is needed.
METHOD C -- ALTERNATIVE
As an alternative to Method B, when the floor surface is uneven, the field
sample may be placed on a canvas blanket and mixed with a shovel, or by
alternatively lifting each corner of the blanket and pulling the blanket over the
sample toward the diagonally opposite corner causing the material to be rolled.
Flatten and divide the pile as described in Method B, or if the surface beneath the
blanket is too uneven, insert a stick or pipe dividing the pile into two equal parts.
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Remove the stick leaving a fold in the canvas between the sample halves.
Slide the stick under the canvas blanket again at a right angle to the first division
and dissecting the two halves of the sample through their centers. Lift the stick
evenly from both ends dividing the sample into equal quarters. Remove two
diagonal parts including the fine material and clean the area. Successively mix and
quarter the remaining material until the desired sample size is obtained.
Note: The quartering method is fairly time intensive and thus is generally used in
situations where an adequate mechanical splitter is unavailable. Diligence and care
is required to ensure that the samples obtained by quartering remain
representative of the entire field sample.
STANDARD TEST METHOD FOR TOTAL EVAPORABLE MOISTURE CONTENT OF
AGGREGATE BY DRYING
REFERENCED STANDARD: ASTM C566-96 / AASHTO T255-92
The moisture content in aggregate is used to determine the binder content for
HMA during production of the mixture in a plant. The procedure requires that a known
amount of aggregate be obtained, the aggregate heated to remove the moisture, and the
percentage of moisture determined. Ovens, hot plates, heat lamps or microwave ovens
are used for heating the sample.
Apparatus
Balance sensitive to 1.0 gram
Source of Heat (oven, electric or gas hot plate, electric heat lamps, or microwave oven)
Sample Container, suitable for method of heating
Procedure
1. Weigh the sample and record the weight
2. Dry the sample until there is less than 0.1% change in weight over subsequent
weighings.
3. Record the weight of the sample after the sample has cooled sufficiently not to
damage the balance.
Sample Problem:
Given the following information, determine the percent of moisture content in the Sand
and No. 57.
Given:
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Sand
Weight of wet sample = 585 grams
Weight of dry sample = 540 grams
No. 57
Weight of wet sample = 1205 grams
Weight of dry sample = 1190 grams
Absorption
Sand = 0.5%
No. 57 = 0.9%
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝐶𝑜𝑛𝑡𝑒𝑛𝑡 =
𝑊𝑡. 𝑜𝑓 𝑊𝑒𝑡 − 𝑊𝑡. 𝑜𝑓 𝐷𝑟𝑦
× 100 − %𝐴𝑏𝑠.
𝑊𝑡. 𝑜𝑓 𝑑𝑟𝑦
Solution:
Sand
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝐶𝑜𝑛𝑡𝑒𝑛𝑡 = [(
585−540
540
) × 100] − 0.5% = 7.8%
No. 57
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝐶𝑜𝑛𝑡𝑒𝑛𝑡 = [(
1205 − 1190
) × 100] − 0.9 = 0.4%
1190
SIEVE ANALYSIS OF AGGREGATES
REFERENCED STANDARD: ASTM C 136-84a, AASHTO T27-93,
ASTM C33 / C33M-18, AASHTO T-27
Sieve analysis which is also known as gradation test is a laboratory test procedure that is an
effective way of analyzing or determining the particle size distribution of coarse aggregates within a
given sample. The process separates fine particles from coarser particles by passing the material
through a number of sieves of different mesh sizes. Particle size distribution is defined using the mass
and volume. Particle size determinations on large samples of aggregate are necessary to ensure that
aggregates perform as intended for their specified use. Particle size distribution can affect a wide range
of properties such as the strength of concrete, solubility of a mixture, surface area properties, and even
their taste. This information can then be used to determine compliance with design and production
requirements. Data can also be used to better understand the relationship between aggregates or
blends and to predict trends during production. In this method, the soil is sieved through a set of sieves.
A known mass of material is placed on top of a group of nested sieves (arranged in order of decreasing
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size from top to bottom) and mechanically shaken for a designated period of time. Particles move
horizontally or vertically through sieve mesh.
Sieves are wire screen having square openings. Size of these openings gives the sieves their
name which is called sieve number. A sieve with a mesh opening of 4.75 mm is designated as 4.75 mm
Sieve (Sieve number written on sieve). Similarly, a 600-micron sieve refers to a sieve which has a mesh
opening of 0.600 mm. The two major standards governing test sieves and appropriate sizes are ASTM
E11 and ISO 565/3310-1, both of which specify parameters for aperture dimensions, mesh size, and
statistical variations. Opening sizes and mesh diameters for test sieves are often duplicated between
these two standards, making it easier to select the proper sieve size for your material. Sieve mesh
opening sizes range from 5in (125mm) down to #635 (20µm).
There are two methods in sieving analysis, the Manual Sieving Method and the Mechanical
Sieving Method. Manual sieving method is carried out in places where there is no electricity and
mainly used in, onsite differentiation among large and small particles. Mechanical sieving method is
used in laboratories to assure the quality and this is the widely used method in present days. In
mechanical sieving the method can be classified into two further groups depending on their sieving
movement as horizontal movement sieving method and vertical movement sieving method. The
vertical movement sieving method is also known as throw-action sieving and vibratory sieving
methods.
There are two ways or methods in weighing the material retained on each of the sieves, the Dry
Sieve Analysis and Wet Sieve Analysis. Dry sieve analysis is considered mostly and here the testing
particles (specimen) are in dry state. Wet sieve analysis is carried out after the dry sieve analysis. The
purpose of the wet sieve analysis is to remove all the particles which are finer than 75 microns (of the
last sieve) particles from the sample so that we arrive at the correct sieve analysis results.
In performing sieve test one must consider and know the two categories of coarse grains soils.
The portion of soil, which contains particle size bigger than 4.75 mm is retained on the sieve. This
portion is called gravel fraction. Gravels, having grain size greater than 4.75 mm. The portion of soil,
which contains particle size less than 4.75 mm passed through the sieve. This portion is called sand
fraction. Sand, having grain size smaller than 4.75 mm. For gravel fractions we require sieves of sizes
80 mm, 40 mm, 20 mm, 10 mm and 4.75 mm. This set is called set of coarse sieves as it sieves coarser
part of the coarse soils. Second set of sieves for sand fractions consists sieves of sizes 2 mm, 1 mm, 600
µ, 425 µ, 212 µ, 150 µ and 75 µ. If we didn’t mention, then 1 mm that is millimeter is equal to 1000
micrometer which we denote as letter micron. So 1 mm is equal to 1000 micron. So here 600 microns
is actually 0.6 mm. This set of sieves is called set of fine sieves as it sieves finer part of the coarse soils.
A test procedure for an effective determination of the particle size distribution of coarse
aggregates. First, find a sample that ensure that aggregates perform as intended for their specified used.
Make sure that sample is clean and no foreign materials, such as, feces etc. Then, collect the chosen
sample. After that, transport it to the testing laboratory. When it arrived in the testing center, prepare
it for testing. Lastly, test and record the result.
Part of testing is weighing the material. There are two methods of weighing the sample. First is
the Cumulative Method where each sieve fraction, beginning with the coarsest, is placed in a
previously tared pan and weighed. This process is repeated until all fractions and the bottom pan have
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been added and weighed. This is a good time saving option since you don’t have to empty out or tare
the pan on the scale. Second one is the Fractional Method where operator weighs the contents of each
sieve fraction separately, waiting to discard material until the entire test is complete. The technician
then calculates the amount retained and passing the sieve to the nearest 0.1% by total mass.
In Cumulative Method, as each retained fraction is added, divide the cumulative mass by the total
mass of the sample and multiply by 100 to calculate percent retained. Subtract the cumulative percent
retained on a given sieve from 100 to calculate percent passing.
(Cumulative Mass / Total Mass) × 100 = Cumulative % Retained
100 – (Cummulative % Retained) = Cumulative Retained Passing
On the other hand, Fractional Method, divide the mass retained on each sieve by the total and
multiply by 100 to calculate percent retained. Calculate percent passing by subtracting the percent
retained on the sieve nested beneath.
[Fractional Mass (on each sieves) ÷ Total Mass] × 100 = (% Fractional Retained)
(% Fractional Retained) – (% Retained on the sieve below) = (% Fractional Passing)
In calculating the percentage of amount of soil retained on each sieve as weight of retained soil
on the sieve divided by total weight of soil sample multiplied by 100. This way we know what
percentage of the total weight is retained on a particular sieve. Percentage weight retained on the 1st
sieves is w1 divided by W multiply by 100.
For calculation purposes and to determine some important characteristics, we also calculate two
values. First one is cumulative percentage retained. Now cumulative percentage retained of any sieve
is percentage weight retained on that sieve plus all percentage weight retained on all the sieves above
it. Cumulative percentage retained is the total percentage amount of soil which could not pass the
particular sieve. In other words, this percent amount of soil has grain size greater than the sieve
number.
Second value we calculate is percentage finer, using which we plot a graph called particle size
distribution curve. Percentage finer, as name suggests, is the percentage amount of soil which is finer,
than a particular sieve.
Testing tips:
❖ Avoid overloading sieves.
❖ Allow enough time on a sieve shaker or testing screen for complete separation.
❖ Watch for degradation.
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❖ Consider reducing shaker time intervals or using a different method.
❖ Check sieves for wear, torn mesh or distorted openings regularly.
❖ Do not use tools or probes to dislodge trapped particles.
❖ Take care when transferring material to the tare weighing pan.
❖ Don’t forget to pre-dry the sample.
Sample Problem: From the results of a sieve analysis, shown below, determine:
a.
b.
c.
d.
The percent finer than each sieve and plot a grain size distribution curve.
D10, D30, D60 from the grain-size distribution curve.
The uniformity coefficient, Cu. and
The coefficient of gradation, Cc.
Table 1
Sieve Number
4
10
20
40
60
80
100
200
Pan
Mass of soil retained on each sieve (g)
0
40
60
89
140
122
210
56
12
Solution:
a.
Mass of Soil
Cumulative percent
Percent retained
retained on
retained on each
of each sieve (%)
each sieve (g)
sieve (%)
4
0
0
0
10
40
5.49
5.49
20
60
8.23
13.72
40
89
12.21
25.93
60
140
19.20
45.13
80
122
16.74
61.87
100
210
28.81
90.68
200
56
7.68
98.36
Pan
12
1.64
100
729
Percent Retained = (Mass of Soil Retained/Total Mass of Soil)
Sieve
Number
No. 4 Sieve
Percent finer
(%)
100
94.51
86.28
74.07
54.87
38.13
9.32
1.64
0
No. 80 Sieve
0
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
122
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
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% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 0%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 16.74%
No. 10 Sieve
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 =
No. 100 Sieve
40
729
× 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 =
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 5.49%
No. 20 Sieve
210
729
× 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 28.81%
No. 200 Sieve
60
210
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 8.23%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 7.67%
No. 40 Sieve
Pan
89
12
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 12.21%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 1.65%
No. 60 Sieve
140
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 729 × 100%
% 𝑅𝑒𝑡𝑎𝑖𝑛𝑒𝑑 = 19.20%
Distribution Curve
b. D10, D30, D60 from the grain-size distribution curve.
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c. The uniformity coefficient, Cu
D10 = 0.15mm
𝐶𝑢 =
D30 = 0.17mm
D60 = 0.28mm
𝐷60 0.28𝑚𝑚
=
= 1.9
𝐷10 0.15𝑚𝑚
d. The coefficient of gradation, Cc
𝐶𝑐 =
𝐷30 2
(0.17𝑚𝑚)2
=
= 0.69
𝐷10 𝑥 𝐷60 0.28𝑚𝑚 𝑥 0.15𝑚𝑚
Determination of Unit Weight of Aggregates
There are two standard test methods in the determination for unit mass (weight) of an
aggregate, the Loose Method and the Rodded Method, using ASTM C29.
Procedure using Loose Method:
•
•
•
•
•
Determine the weight of the empty bucket.
Fill the bucket to overflowing by means of shovel or scoop. Exercise care to prevent
segregation of the particle size of the sample.
Level the surface of the aggregate using straightedge.
Clean the outside of the bucket and remove excess dust and particles.
Determine the mass of the bucket with aggregates, and record the data.
Procedure using Rodded Method:
•
•
•
Fill the bucket one-third full.
Rod the layer of aggregate with 25 strokes of the tamping rod evenly distributed over
the surface.
Fill the bucket two-thirds full again and rod 25 times.
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•
•
•
•
Fill the bucket to over flowing and rod again for 25 times.
After rodding, level the surface with a straightedge.
Clean the surface of the bucket and remove excess materials.
Determine the weight of the bucket with aggregates and record data.
After using either of the two methods, unit weights are then calculated with the formula as follows:
SPECIFIC GRAVITY & ABSORPTION DETERMINATION OF FINE AND COARSE AGGREGATES
REFERENCED STANDARD: ASTM C127-88, AASHTO T85-91
Specific Gravity is the ratio of the weight of a given volume of aggregate to the weight of an equal
volume of water.
Absorption is a measure of the amount of water that an aggregate can absorb into its pore structure
and is determined by the same test procedure.
Aggregate is a granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement
concrete, or iron blast-furnace slag, used with a hydraulic cementing medium to produce either
concrete or mortar.
There are two types of aggregates:
•
•
Fine Aggregates – are particles entirely passing the 4.75 mm (No. 4) sieve, and predominantly
retained on the 75 µm sieves.
Coarse Aggregates– are aggregates that will not pass through a sieve with 4.75 mm openings.
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I.
Specific Gravity Determination of Aggregates
For fine aggregates, the specific gravity may be expressed as bulk oven dry (OD), bulk saturated
surface dry (SSD), or apparent specific gravity (A). Let us first define the terms:
A. Bulk Dry Specific Gravity – It is used to determine the specific gravity of a compacted aggregate
by determining the ratio of its weight to the weight of an equal volume of water.
In this test, the aggregates have to be:
• Dry (no water in sample).
• Saturated surface dry (SSD, water fills the HMA air voids).
• Submerged in water (underwater).
B. Bulk Saturated Surface Dry Specific Gravity (SSD) – The ratio of the weight in air of a unit
volume of aggregate, including the weight of water within the voids filled to the extent achieved
by submerging in water for approximately 15-19 hours, to the weight in air of an equal volume
of gas-free distilled water at a stated temperature.
SSD (Saturated, Surface Dry) – This is a condition in which the aggregate has been soaked in
water and has absorbed water into its pore spaces. The excess, free surface moisture removed
so that the particles are still saturated, but the surface of the particle is essentially dry.
C. Apparent Specific Gravity (Gsa) – It is the ratio of the weight in air of a unit volume of the
impermeable portion of aggregate (does not include the permeable pores in aggregate) to the
weight in air of an equal volume of gas-free distilled water at the stated temperature.
D. Absorption (% Abs) – The increase in weight of aggregate due to water in the pores of the
material, but not including water adhering to the outside surface of the particles.
Specific Gravity Determination of Coarse Aggregates
Perform calculations and determine values using the appropriate formula below. In these formulas,
A = oven dry mass, B = SSD mass, and C = weight of SSD in water.
A. Bulk Oven Dry Specific Gravity (OD)
B. Bulk Saturated Surface Dry Specific Gravity (SSD)
C. Apparent Specific Gravity
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D. Absorption (% A)
Materials needed (Coarse Aggregates)
•
•
•
•
•
•
Water Tank
Cloth
Coarse Aggregates
Tray
Wire Basket
Balance scale
Procedures for Coarse Aggregates:
1. Dry the test sample to constant mass at a temperature of 110 ±5°C (230 ±9°F) and cool in air at room
temperature for 1 to 3 hours.
2. Immerse the aggregate in water at room temperature for a period of 15 to 19 hours.
3. Place the empty basket into the water bath and attach to the balance. Inspect the immersion tank to
ensure the water level is at the overflow outlet height. Tare the balance (set to 0) with the empty basket
attached in the water bath.
4. Remove the test sample from the water and roll it in a large absorbent cloth until all visible films of
water are removed. Wipe the larger particles individually.
5. Determine the SSD mass of the sample, and record this and all subsequent masses to the nearest 0.1
g or 0.1 percent of the sample mass, whichever is greater. Designate this mass as “B”.
6. Re-inspect the immersion tank to insure the water level is at the overflow outlet height. Immediately
place the SSD test sample in the sample container and weigh it in water maintained at 23.0 ±1.7°C (73.4
±3°F). Shake the container to release entrapped air before recording the weight. Designate this
submerged weight as “C”.
7. Remove the sample from the basket. Ensure all material have been removed. Place in a container of
known mass.
8. Dry the test sample to constant mass and cool in air at room temperature for 1 to 3 hours. Designate
this mass as “A”.
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II.
Specific Gravity and Absorption of Fine Aggregates
Perform calculations and determine values using the appropriate formula below. In these formulas,
where: A = Oven dry weight, B = SSD weight, C = Weight of SSD in water.
A. Bulk Dry Specific Gravity
B. Bulk Saturated Surface Dry Specific Gravity (SSD)
C. Apparent Specific Gravity
D. Absorption (% A)
Materials needed (Fine Aggregates):
•
•
•
•
•
•
Pycnometer
Oven (Soil Testing)
Distilled Water
Tray
Balance scale
Fine aggregates
Procedure for Fine Aggregates:
1. Thoroughly mix the sample and reduce the sample if required. The sample size for this procedure is
approximately 1000g of material passing the 4.75 mm sieve (mesh strainer).
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2. Dry test samples to constant weight in an oven set at 230 ± 9°F (110 ± 5°C). Cool the sample at room
temperature for 1 to 3 hours. After the cooling period, immerse the sand in water at room temperature
for a period of 15 to 19 hours. This is the recommended procedure to eliminate the need to pour excess
water from the sand prior to testing. The decantation process is time consuming and difficult, since
great care must be taken to avoid pouring some of the sample along with the water.
3. Pour water from sample, avoiding loss of fines. Spread the sample on a flat, non-absorbent surface or
tray. Stir the sample occasionally to assist in homogeneous drying. A current of warm air may be used
to assist drying procedures; however, fine particles may be lost with this procedure if not careful.
4. Determine the SSD condition of the sand using the Cone Test. Throughout the process of drying in
Step 3, test the sand for SSD condition using the cone method. Place the cone with the large diameter
down on a glass plate. Fill cone to overflowing with drying sand. Lightly tamp the fine aggregate into
the mold with 25 light drops of the tamper. Each drop should start about 1/5 in. above the top surface
of the fine aggregate. Remove loose sand from base and carefully lift the mold vertically. If surface
moisture is still present, the fine aggregate will retain the molded shape. When the sand achieves an
SSD condition, the sand will slump.
5. Calibrate a specific gravity flask pycnometer by filling with water at 73.4 ± 3°F (23 ± 1.7°C) to the
calibration line. Record this weight as the weight of the pycnometer filled with water to the nearest
0.1g.
6. Place the SSD sand into the pycnometer and fill with water (set at 73.4 ± 3°F (23 ± 1.7°C)) to 90% of
pycnometer capacity.
7. Bring the pycnometer to the pycnometer-calibrated capacity with additional water. If bubbles
prevent the proper filling of the pycnometer, adding a few drops of isopropyl alcohol is recommended
to disperse the foam. Place the pycnometer in a water bath at the regulated temperature and allow the
sample to equalize.
8. Determine the total weight of pycnometer, specimen, and water. Record the weight to the nearest
0.1g as weight of pycnometer with sample and water.
Additional:
The common errors during testing:
•
•
•
•
•
•
•
•
•
Getting the aggregate SSD - neither wetter nor drier.
Balance calibration errors.
Ensuring that the change in height of the water when the sample is submerged is
compensated for.
Not allowing the sample to become fully saturated before testing for SSD and Immersed
mass.
Full drying to constant mass.
Over-drying sensitive materials (driving off water that is actually part of the sample) either
by poor temperature control, or the characteristics of the aggregate.
Water temperature effects (its density).
Purity of the water.
Not allowing sufficient time for the balance to stabilize its reading.
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•
•
•
Removal of air bubbles when weighing under water.
Loss of particles, due to poor technique (carelessness), insufficient washing at the beginning,
friable particles.
Having a sample where particles are less dense than water. Some or all thereof.
Problem : Determine calculations based on appropriate formula.
A = Weight of oven dry sample
B = Weight of Pycnometer with water only
S = Weight of Saturated Surface Dry of sample
C = Weight of Pycnometer with sample and water
Bulk Specific Gravity (Gsb)
Gsb = A / (B + S – C)
Bulk SSD Specific Gravity (Gsb SSD)
Gsb SSD = S / (B + A – C)
Apparent Specific Gravity (Gsa)
Gsa = A / (A + B – C)
Absorption (% Abs)
% Abs = [(S – A) / A] x 100
Trial
A
B
S
C
B+S-C B+A-C
1
497.1 670.7 500.05 938.2 232.55
229.6
2
496.7 679.6 499.77 938.2 241.17
238.1
3
496.5 671.6 499.61 938.2 233.01
229.9
Trial
1
2
3
Gsb SSD, S /
(B + S – C)
2.15
2.07
2.14
Gsb, A / (B
+ S – C)
2.14
2.06
2.13
Gsa, A / (B
+ A – C)
2.17
2.09
2.16
S-A
2.95
3.07
3.11
% Abs., [(S –
A) / A] x 100
0.59
0.62
0.63
STANDARD METHOF OF TEST FOR BULK DENSITY (“Unit Weight”) AND VOIDS IN AGGREGATE
(UNIT WEIGHT DETERMINATION)
REFERENCED STANDARD: ASTM C29/29M-91a; AASHTO 19/19M-93
I. OBJECTIVES
1. To determine the unit weight of an air-dry mixed aggregate
2. To visualize how some certain aggregate properties influence the voids in aggregates
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3. To learn the importance of the capacity of the measure required for a given aggregate size for
testing
II. SCOPE
This test method covers the determination of bulk density (“unit weight”) of aggregate in a
compacted or loose condition, and calculated voids between particles in fine, coarse, or mixed
aggregates based on the same determination.
This test method is applicable to aggregates not exceeding 125 mm (5 in.) in nominal maximum size.
Unit weight is the traditional terminology used to describe the property determined by this test method,
which is weight per unit volume (more correctly, mass per unit volume or density).
γ=M/V
γ = Unit Weight
M = Mass
V = Volume
III. TERMINOLOGY
▪
BULK DENSITY - the mass of a unit volume of bulk aggregate material, in which the volume
includes the volume of the individual particles and the volume of the voids between the particles.
Expressed in kg/m3(lb/ft3)
▪
UNIT WEIGHT (mass) per unit volume
▪
WEIGHT - force exerted on a body by gravity
▪
VOIDS - the space between particles in an aggregate mass not occupied by solid mineral matter.
IV. SIGNIFICANCE AND USE
•
This test method is often used to determine bulk density values that are necessary for use for
many methods of selecting proportions for concrete mixtures.
•
The bulk density also may be used for determining mass/volume relationships for conversions
in purchase agreements. However, the relationship between degree of compaction of aggregates
in a hauling unit or stockpile and that achieved in this method is unknown.
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V. APPARATUS/MATERIALS
1. WEIGHING BALANCE
The balance shall have sufficient capacity, be readable to 0.1 percent of the sample mass,
or better, and conform to the requirements of M 231.
2. TAMPING ROD
A round, straight steel rod, 16 mm (5/8 in.) in diameter and approximately 600 mm (24
in.) in length, having one end rounded to a hemispherical tip of the same diameter as the
rod.
3. CYLINDRICAL METAL MEASURE
It shall be watertight, with the top and bottom true and even, and sufficiently rigid to
retain its form under rough usage. The measure should have a height approximately
equal to the diameter, but in no case shall the height be less than 80 percent nor more
than 150 percent of the diameter.
4. SHOVEL OR SCOOP
of convenient size for filling the measure with aggregate.
5. CALIBRATION EQUIPTMENT
A supply of water pump or chassis grease that can be placed on the
prevent leakage.
VI. PROCEDURE
A. CALIBRATION OF THE MEASURE
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1. Select an appropriate measure according to the nominal size of the aggregate sample.
2. Weigh the empty measure.
3. Fill the measure with water at room temperature and cover with a glass plate to exclude air
bubbles and to remove excess water.
4. Weigh the measure filled with water. Make the necessary calculations to determine the mass
of the water that filled the entire volume of the measure. The actual volume of the measure shall
be atleast 95% of the nominal volume in the table
5. Take the temperature reading of the water used to fill the measure and determine its density
using Table 2. interpolate as necessary.
6. Compute the volume of the measure by dividing the mass of the water required to fill the
measure by its density.
7. If there is a reason to question the accuracy of the measure, recalibrate or replace the water
as needed.
B. UNIT WEIGHT DETERMINATION
1. Select a sample of oven-dry mixed aggregate approximately 125% to 200% of the volume of
the measure.
For aggregates <37.5 mm, use the rodding procedure
For aggregates >37.5 mm but <150 mm, use the jigging procedure
2. Fill the measure one-third full. Level and apply 25 strokes tamping evenly over the surface.
3. Fill the measure two-thirds ful. Level and tamp as in step 2. Only enough force should be used
to cause the tamping rod to just penetrate the last layer of aggregate placed in the measure.
4. Fill to overflowing, tamp as before and strike off the surplus by rolling the tamping rod over
the surface or level off using a straight edge. Do not compress the aggregates.
5. Determine the net weight of the aggregate in the measure and compute the unit weight. Make
at least two trials. Result should agree within one percent.
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VII. DATA ANALYSIS
1. DENSITY
M = (MT – Mm) / V
where:
P = unit weight of the aggregate (kg/m^3)
MT = combined mass of the aggregate and he
measure (kg)
Mm = mass f the measure (kg)
V = volume of the measure (m^3)
2. UNIT WEIGHT
γ = (WT – Wm) / V
where:
γ = unit weight of aggregate (kN/m^3)
WT = total weight of aggregate and measure (kN)
Wm = weight of measure (kN)
V = volume of measure (m^3)
3. VOID CONTENT
% Voids = { [GS(dry) x pW – pagg] / GS(dry)(pW) } x100
where:
pagg = density of aggregate (kN/m^3)
pW = density of water (kg/m^3)
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GS(dry) = bulk of specific gravity on the dry
basis
Problem: The following table shows the result of bulk density (unit weight) and voids in Aggregate
test. Calculate the Bulk Density and % of voids.
Volume of
Wt. of the
Sample
the
Measure,
No.
Measure, V.
W1, gm
(cm3)
1
2
3
Computation:
3000
3000
3000
2686
2686
2686
Wt. of the
Measure +
Sample,
W2, gm
6878
6752
6793
Sample No. 1
𝑀=
6878 − 2686
3000
𝑀 = 1.397 𝑔𝑚/𝑐𝑚3
% 𝑉𝑜𝑖𝑑𝑠 =
7953 − 6878
× 100
3000
% 𝑉𝑜𝑖𝑑𝑠 = 35.83%
Sample No. 2
𝑀=
6752 − 2686
3000
𝑀 = 1.355 𝑔𝑚/𝑐𝑚3
% 𝑉𝑜𝑖𝑑𝑠 =
7662 − 6752
× 100
3000
% 𝑉𝑜𝑖𝑑𝑠 = 30.33%
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Wt. of the
Measure +
Sampele +
Water, W3,
gm
7953
7662
7846
Bulk
Density
%
Void
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Sample No. 3
𝑀=
6793 − 2686
3000
𝑀 = 1.369 𝑔𝑚/𝑐𝑚3
% 𝑉𝑜𝑖𝑑𝑠 =
7846 − 6793
× 100
3000
% 𝑉𝑜𝑖𝑑𝑠 = 35.1%
Volume of
Wt. of the
Sample
the
Measure,
No.
Measure, V.
W1, gm
(cm3)
1
2
3
3000
3000
3000
Wt. of the
Measure +
Sample,
W2, gm
2686
2686
2686
6878
6752
6793
Wt. of the
Measure +
Sampele +
Water, W3,
gm
7953
7662
7846
Average
Bulk
Density
%
Void
1.397
1.355
1.369
1.374
35.83
30.33
35.10
33.75
DETERMINATION OF MOISTURE CONTENT OF COARSE AND FINE AGGREGATES
REFERENCED STANDARD: ASTM C566-96; AASHTO T255-92
I. OBJECTIVES
1. To learn the procedures for determining the amount of moisture in aggregates.
2. To quantify the components of evaporable moisture in aggregates
3. To calculate and compare the total evaporable moisture with surface moisture
CHARACTERISTICS CONTROLLED BY POROSITY
1. DENSITY
2. ABSORPTION AND SURFACE MOISTURE
3. SOUNDNESS
➢ ABSORPTION AND SURFACE MOISTURE
Moisture Conditions of Aggregates
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1. Damp or Wet
2. Air Dry
3. Saturated-surface Dry
4. Oven Dry
II. TERMINOLOGY
•
MOISTURE CONTENT – quantity of water contained in a material
•
AGGREGATE – a material or structure formed from a loosely compacted mass of fragment
•
VOIDS – spaces or gaps inside a material
•
ABSORPTION – action by which a material absorbs or is absorbed by another
•
SURFACE MOISTURE (FREE MOISTURE) – absorbed water and moisture coating the surface
III. APPARATUS/MATERIALS
•
COARSE AGGREGATE SAMPLE
•
OVEN
•
SAMPLE CONTAINER
•
BALANCE SENSITIVE TO 1.0 GRAM
•
SIEVE
IV. PROCEDURES
A. TOTAL MOISTURE CONTENT OF COARSE AGGREGATES
1. Obtain the prescribed test sample size
2. Weigh the sample to the nearest 1.0 gram. Due this quickly to avoid moisture loss.
3. Under controlled temperature, dry the sample in an oven. The sample is completely dry when
further drying would cause less than 0.1 percent additional loss in weight.
4. Weigh the dry sample to the nearest 1.0 gram.
B. FREE MOISTURE CONTENT OF COARSE AGGREGATE IN THE SSD CONDITION
1. Obtain the prescribed test sample size.
2. Soak the sample for 24 hours.
3. Weigh the wet sample to the nearest 1.0 gram. Avoid moisture loss.
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4. Using a towel, wipe the surface dry until it loses its shine.
5. Immediately weigh the SSD sample to the nearest 1.0 gram.
V. DATA ANALYSIS
1. Total Moisture Content
MC
[(MT – MO) : MO] x 100%
A
[(MSSD – MO) : MO] x 100%
2. Absorption
VI. EXAMPLE
The original weight of the sample is 546.2 grams and the dry weight of the sample is 541.2 grams. Find
the moisture content to the nearest 1.0 grams.
DETERMINATION OF FINENESS MODULUS
Fineness Modulus of Sand
Fineness modulus of sand (fine aggregate and coarse aggregate) is an index number which
represents the mean size of the particles in sand. It is calculated by performing sieve analysis
with standard sieves. The cumulative percentage retained on each sieve is added and divided by
100 gives the value of fineness modulus.
Fine aggregate means the aggregate which passes through 4.75mm sieve. To find the fineness
modulus of fine aggregate we need sieve sizes of 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm and
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0.15mm. Fineness modulus of finer aggregate is lower than fineness modulus of coarse
aggregate. On the other hand, coarse aggregate means the aggregate which is retained on
4.75mm sieve when it is sieved through 4.75mm. So, in the calculation of coarse aggregate we
need all sizes of sieves. To find fineness modulus of coarse aggregate we need sieve sizes of
80mm, 40mm, 20mm, 10mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm and 0.15mm.
Determination of Fineness Modulus of Sand
To determine the fineness modulus, we need standard sieves, mechanical sieve shaker
(optional), dry oven and digital weight scale.
A. Sample preparation - Take a sample of fine or coarse aggregate in pan and placed it in dry
oven at a temperature of 100 – 110oC. After drying take the sample and note down its weight.
B. Test Procedure
1. Take the sieves and arrange them in descending order with the largest sieve on
top.
It is suggested that, to know the exact value of fineness modulus for coarse
aggregate, mechanical shaker will give better value than hand shaking because of
more number of sieves and heavy size particles.
2. If mechanical shaker is used, pour the sample in the top sieve and then close it
with sieve plate. Then switch on the machine and shaking of sieves should be done
at least 5 minutes.
If shaking is done by the hands then pour the sample in the top sieve and close it
then hold the top two sieves and shake it inwards and outwards, vertically and
horizontally. After some time shake the 3rd and 4th sieves and finally last sieves.
3. After sieving, record the sample weights retained on each sieve. Then find the
cumulative weight retained. Finally determine the cumulative percentage
retained on each sieves. Add all the cumulative percentage values and divide with
100 then we will get the value of fineness modulus.
Calculation of Fineness Modulus of Sand – Fine Aggregate
Dry weight of sample = 1000g
After sieve analysis the values appeared are tabulated below.
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Therefore, fineness modulus of aggregate = (cumulative % retained) / 100 = (275/100) = 2.75
Fineness modulus of fine aggregate is 2.75. It means the average value of aggregate is in between
the 2nd sieve and 3rd sieve. It means the average aggregate size is in between 0.3mm to 0.6mm
as shown in below figure.
Values of Fineness Modulus of Sand:
Fineness modulus of fine aggregate varies from 2.0 to 3.5. Fine aggregate having fineness
modulus more than 3.2 should not considered as fine aggregate. Various values of fineness
modulus for different sands are detailed below.
Calculation of Fineness Modulus of Sand – Coarse Aggregate
Dry weight of sample = 5000g
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After sieve analysis the values appeared are tabulated below.
Therefore, fineness modulus of coarse aggregates = sum (cumulative % retained) / 100 =
(717/100) = 7.17
Fineness modulus of 7.17 means, the average size of particle of given coarse aggregate sample is
in between 7th and 8th sieves, that is between 10mm to 20mm.
Limits of Fineness Modulus:
Fineness modulus of coarse aggregate varies from 6.5 to 8.0. And for all in aggregates or
combined aggregates fineness modulus varies from 3.5 to 6.5. Range of fineness modulus for
aggregate of different maximum sized aggregates is given below.
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SOUNDNESS TEST
The soundness test determines the resistance of an aggregate to disintegration by weathering
(the breakdown of rocks at the Earth’s surface) and freeze-thaw cycles (the freezing and thawing of
water inside the aggregate). Aggregates are durable if it has higher resistant to weathering. The durable
aggregates are less likely to degrade in the field and potentially less failure.
(a)
(b)
Figure 1. Before and after Soundness Test
The soundness test repeatedly submerges an aggregate sample in a sodium sulfate (Na2SO4)
or magnesium sulfate (MgSO4) solution. Because of this solution, the salt crystals will be formed in
the aggregate’s water permeable pores.
The formation of these crystals creates internal forces that apply pressure on the pores of the
aggregate and tend to break the aggregate (Figure 1 - b). There are specified number of submerging and
drying repetitions which should be follow. After that, the aggregate is sieved to determine the
percentage loss of material.
•
Durability and soundness are terms typically given to an aggregate’s weathering resistance
characteristic.
Types of Soundness Tests
1. Sulfate Soundness – (AASHTO T 104) This test subjects the aggregate samples to repeated
immersion in either sodium sulfate or magnesium sulfate solution. Wu, Parker and Kandhal
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(1998) report that just over half of the states have a sodium sulfate soundness requirement,
while about one-fifth have a magnesium sulfate soundness requirement.
2. Freezing and Thawing Soundness - this test was specified in AASHTO T 103 and similar to the
sulfate soundness tests, however it uses actual freeze-thaw cycles with water or a weak ethyl
alcohol – water solution.
3. Aggregate Durability Index - This test, specified in AASHTO T 210, measures the relative
resistance of an aggregate to produce detrimental clay-like fines when subjected to mechanical
methods of degradation.
STANDARD METHOD OF TEST FOR SOUNDNESS OF AGGREGATE BY USE OF SODIUM SULFATE
OR MAGNESIUMSULFATE
REFERENCED STANDARD: AASHTO T 104
Apparatus Required: Balance, Oven, Sieves, Wire Mesh Basket, Container, Chemical Solutions
Basic Procedure:
1. Prepare the sulfate solution. When used, the sodium sulfate solution’s specific gravity should
be between 1.154 to 1.171 and the magnesium sulfate solution’s specific gravity should be
between 1.297 and 1.306.
2. Prepare the Fine Aggregate. Obtain a sample that is large enough to yield at least 100 g of
material on each of the following sieves: No. 50 (0.300 mm), No. 30 (0.600 mm), No. 16 (1.18
mm), No. 8 (2.36 mm) and No. 4 (4.75 mm). Thoroughly wash the sample on a No. 50 (0.300
mm) sieve and dry it in an oven at 230°F (110°C). Obtain 100 g of each size, record the weight,
and place in separate containers for the test
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3. Prepare the coarse aggregate. Obtain enough material to yield at least the weights listed below:
4. Place each sample in separate containers for the test.
5. Immerse the samples in the prepared solution of sodium sulfate or magnesium sulfate for 16 to
18 hours. Cover the containers to reduce evaporation and prevent contamination and maintain
the temperature between 20.3 to 21.9°C for the immersion period.
6. Remove the samples and allow them to drain for 15 minutes.
7. Place the samples into an oven set at 230°F (110°C).
8. Allow the samples to dry until the change in mass is less than 0.1 percent over a 4 hour period
(the weight is checked on four hour intervals without letting the sample cool).
9. After the samples reach constant mass allow the samples to cool to 68 to 77°F (20 to 25°C);
cooling may be aided using an air conditioner or fan.
10. Repeat the immersion process (steps 4 through 8) until the specified number of cycles is
obtained (five cycles are normally performed).
11. After the final cycle is complete and the sample has cooled, wash the sample.
12. Check the thoroughness of washing by obtaining a sample of rinse water after it has passed
through the samples and adding 0.2 M barium chloride. If the sample water becomes cloudy
when the barium chloride is added, then continue to wash the sample.
13. After washing is complete, dry each fraction of the sample to a constant mass in an oven at 230°F
(110°C).
14. Examine the aggregates.
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Results:
For material that was coarser than 0.75 inches (19 mm) before test, the number of particles in
each fraction before test and the number of particles affected, classified as to number disintegrating,
splitting, crumbling, cracking and flaking is also measured.
Typical Values:
Typical values depend upon the type of soundness test used. The sodium sulfate loss is typically
between about 0 and 15 percent, while the magnesium sulfate loss is typically between about 0
and 30 percent. For a particular aggregate sample, the sodium sulfate loss will tend to be less than
the magnesium sulfate loss by 0 to 20 percent with 5 to 10 percent being most typical.
Calculations (Interactive Equation)
For each aggregate size reported, determine the mass loss (in percent) using the following equation:
Where:
MB = mass before the test
MA = mass after the test
A weighted average (by mass) of each aggregate size tested should be calculated and reported as the
overall mass loss of the sample.
Problem 1 : The following table show the results of soundness and durability of aggregate by use of
Sodium Sulfate test. Calculate the percentage of loss.
Sample
No.
1
2
3
4
5
Wt. of
Sample
before Test,
W1 (gm)
350
350
350
350
350
Wt. of
Sample after
test, W2,
(gm)
310
305
290
281
345
Average
Computation:
Formula
% 𝐿𝑜𝑠𝑠 =
𝑊1 − 𝑊2
𝑥 100
𝑊1
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% Loss
11.43 %
12.86 %
17.14 %
19.71 %
1.43 %
12.51 %
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Sample 1
% 𝐿𝑜𝑠𝑠 =
350 − 310
𝑥 100 = 11.43%
350
Sample 2
% 𝐿𝑜𝑠𝑠 =
350 − 305
𝑥 100 = 12.86%
350
Sample 3
% 𝐿𝑜𝑠𝑠 =
350 − 290
𝑥 100 = 17.14%
350
Sample 4
% 𝐿𝑜𝑠𝑠 =
350 − 281
𝑥 100 = 19.71%
350
Sample 5
% 𝐿𝑜𝑠𝑠 =
350 − 345
𝑥 100 = 1.43%
350
Problem 2: Determine the mass loss (in percent)
Sieve size
No. 8 (2.36 mm)
No. 30 (0.600 mm)
Mass (before test)
100 g
175 g
Mass (after test)
99.4 g
173.8 g
Loss (%)
0.6 %
0.69 %
ORGANIC IMPURITIES IN FINE AGGREGATE (COLOUR TEST)
REFERENCED STANDARD: AASHTO T-21 or ASTM C40
In application, the aggregates must be free of clay, silt, and organic impurities. Organic
impurities, usually in the form of tannic acid and its derivatives, are typically present in fine aggregates
such as sand. If present, these impurities could influence the composition of the cement paste, strength
and setting of the concrete. Organic impurities in fine aggregate are determined by ASTM C40, Organic
Impurities in Sands for Concrete. The excess clay and silt in an aggregate can cause an increase in
shrinkage, affect durability, and cause separation from the other aggregate particles.
The principal value of these test methods is to furnish a warning that injurious amounts of
organic impurities may be present. When the sample subjected to these tests produce a color darker
than the standard color it is advisable to perform the test for the effect of organic impurities on the
strength of mortar in accordance with Test Method.
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Apparatus Required:
•
•
Glass Bottles
Glass Color Standard
Reagent and Standard Color Solution:
•
Reagent Sodium Hydroxide Solution (3 %)—Dissolve 3 parts by mass of reagent grade
sodium hydroxide (NaOH) in 97 parts of water.
Test Sample :
The test sample shall have a mass of about approximately 450 g [1 lb].
Procedure:
1. Fill a glass bottle to the approximately 130-mL [4.5- fluid oz] level with the sample of the fine
aggregate.
2. Add the sodium hydroxide solution until the volume of the fine aggregate and liquid, indicated
after shaking, is approximately 200 mL [7 fluid oz].
3. Stopper the bottle, shake vigorously, and then allow to stand for 24 h.
Determination of Color Value:
•
Glass Color Standard Procedure—To define more precisely the color of the supernatant liquid
of the test sample, five glass standard colors shall be used using the following colors:
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Gardner Color Standard No.
5
8
11
14
16
Organic Plate No.
1
2
3 (standard)
4
5
Reporting:
(a) If the color of the liquid above the fine aggregate is lighter than the reference color (standard), the
amount of organic impurities present in the fine aggregate under test is probably not significant and
the sample is reported as "Pass" on the test report.
(b) If the color of the liquid above the fine aggregate is darker than the reference color (standard), the
sample is reported "Fails" on the test report and desirability of performing further tests to assess the
effect of organic impurities on the concrete-making properties of the fine aggregate under test should
be considered.
ABRASION TEST OF AGGREGATES
REFERENCED STANDARD: AASHTO T 96 or ASTM C 131
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Abrasion Test is the measure of aggregate toughness and abrasion resistance such as crushing,
degradation and disintegration. This test is suggested by AASHTO T 96 or ASTM C 131: Resistance to
Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in Machine.
The aggregates are used for the surface course of the highway pavements and they are subjected to
wearing due to movement of traffic.
When vehicles Travel on the road, the soil particles present between the pneumatic tires of vehicle
and road surface creates the abrasion effect on aggregates. The steel plate wheels of animal driven
vehicles also cause significant abrasion of the road surface.
Therefore, the aggregates used in road construction must be hard enough to resist abrasion. The
resistance offered by aggregate to abrasion is determined in the laboratory by test machine.
The Working principle of abrasion test is to produce abrasive action by use of standard steel balls,
which when mixed with aggregates and rotated in a drum for some specified time for a specific number
of revolutions also causes an impact on aggregates.
The percentage wear of the sample aggregates due to rubbing with steel balls is determined and is
known as Abrasion Value.
Apparatus Used for test:
•
The apparatus is standardized as per IS: 2386 (Part IV) – 1963 consists of:
•
•
Abrasion test Machine.
Abrasive charge balls: Cast iron or steel balls, approximately 48mm in diameter and each
weighing between 390 to 445 gm; six to twelve balls are required
•
Sieve: 1.70 mm, 2.36mm, 4.75mm, 6.3mm, 10mm, 12.5mm, 20mm, 25mm, 40mm,
63mm, 80mm IS Sieves.
The balance of capacity 5 kg or 10 kg is used.
Oven Drying.
Miscellaneous elements like a tray
•
•
•
50mm,
Procedure for Abrasion Test:
1. The aggregates sample consists of clean aggregates dried in an oven at 105° – 110°C. The
aggregates sample should conform to any of the grading shown in below table.
2. Select the Size of aggregate to be used in the test such that it conforms to the grading to be used
in construction, to the maximum extent possible.
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3.
4.
5.
6.
Take exactly 5 kg of the sample for grade A, B, C & D, and 10 kg for grading E, F & G.
Choose the abrasive charge balls as per Table 2 depending on the grading of aggregates.
Place the aggregates and abrasive charge balls on the cylinder and fix the cover.
After that Rotate the machine at a speed of 30 to 33 revolutions per minute. The number of
revolutions should be 500 for grades A, B, C & D and 1000 for grading E, F & G.
7. The machine is stopped after the specified number of revolutions and aggregate sample is
discharged to a tray.
8. The entire stone dust made from a machine is sieved on 1.70 mm IS sieve.
9. The material size more than 1.7 mm size is weighed correct to one gram
Table 1: IS Recommended Test Samples – *Tolerance of ± 12 percent permitted.
Abrasion Test Grading Test Samples
Table 2: Abrasive Balls Charge Selection
Observations:
Original weight of aggregate sample = W1 g
The weight of aggregate sample retained = W2 g
Weight sample passing 1.7mm IS sieve = W1 – W2 g
Abrasion Value = (W1 – W2 ) / W1 X 100
Results:
Abrasion Value =
IS Recommended abrasion test Values for Pavements:
Abrasion test is performed to find the hardness of aggregates. On the basis of this value, the suitability
of aggregates for different road constructions can be judged as per IRC specifications as given
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Self-Help: You can also refer to the sources below to help you further understand the
lesson:
Kultermann E. and Spence, William. (2017). Construction Materials, Methods, and
Techniques: Building a sustainable future. 4th Edition. Australia: Cencage Learning
Ahmed, A. and Sturges, J. (2015). Materials science in construction: an introduction.
Abingdon, Oxon; New York, NY: Routledge
Let’s Check
Activity 1. Now that you know some types and properties of common construction
materials let us try to check how far you had learned. In the space provided, write the
term/s being asked in the following statements:
____________1. A broad category of coarse to medium grained particulate material used in
construction, including sand, gravel, and other more.
____________2. Products of which include building brick, roofing tile, and drainage pipe.
____________3. Those rocks of the earth that have been formed by the natural process of cooling
and crystallization from originally hot and molten magma.
____________4. Marble and slate are examples of what type of rocks according to geological
classification?
____________5. The ratio of mass of a given substance to the mass of water.
___________6. It is the capacity of a material to regain its initial shape and size after removal
of load.
___________7. It is the ability to resist heat conduction and is the reciprocal of thermal
conductivity.
___________8. It refers to the ability of a construction material to resist the effects of chemicals like
acids, salts and alkalis.
___________9. The measure of the resistance of an aggregate to sudden shock or
impact.
__________10. A material used for mixing cement and other adhesive.
2.Calculate the bulk density when the combined mass of aggregate and measure is 1.6 kg and
the mass and volume of the measure itself is 0.9 kg and 0.6, respectively.
3.From the results of a sieve analysis, shown below, determine:
a. The percent finer than each sieve and plot a grain size distribution curve.
b. D10, D30, D60 from the grain-size distribution curve.
c. The uniformity coefficient, Cu. and
d. The coefficient of gradation, Cc.
Table 1
Sieve Number
4
Mass of soil retained on each sieve (g)
0
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10
20
40
60
80
100
200
Pan
44
56
82
51
106
92
85
35
Let’s Analyze
Activity 1. Getting acquainted with the types and properties of some common and
advanced construction materials. what also matters is you should also be able to explain
some its properties. Now, choose 5 most important properties of aggregates which you
believe are essential in determining its suitability for intended used in construction.
Why?
2. Why is aggregate sample reduction important?
3. Why is it important to determine moisture content of aggregates?
4. Differentiate natural to synthetic construction materials.
5. Advantages and disadvantages of structural clay as construction materials.
In a Nutshell
Activity 1. The study of types and properties of construction materials is indeed prerequisite to becoming an engineer.
Based on the topics presented and learning exercises that you have done, please feel free to
write your arguments or lessons learned below. I have indicated my arguments or lessons
learned.
1. Construction materials can be classified as natural such as leaves, twigs, woods, sand, etc. and
synthetic such as cement, concrete, metals, etc.
2. Igneous rocks, sedimentary rocks and metamorphic rocks are building stones under geological
classification.
Now it’s your turn.
3.
4.
5.
Commented [CE1]: Provide are for “In a Nutshell” and
“Q&A”
6.
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7.
8.
9
10.
2. What are the commonly used building stones?
1. granite
2.basalt
Now it’s your turn.
3.
4.
5.
6.
7.
8.
9.
10.
Q&A List
Do you have any question for clarification?
Questions/Issues
Answers
1.
2.
3.
4.
5.
Keywords Index
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Building stones
Structural clay
Aggregates
ASTM
Sample size
Moisture content
Sieve analysis Specific gravity
Bulk density
Soundness test
AASTHO
Absorption
ULO b. Conduct the methods, procedures and formulas of different experiments on
common construction materials according to international standards such as ASTM
& AASTHO.
STANDARD EXPERIMENTS
Refer to Laboratory Manual
Experiment numbers 1 – 11
Week 4 to 5: Unit Learning Outcomes (ULO 2): At the end of the unit, you are expected to:
a. Demonstrate knowledge and understanding of the properties and behaviors of most common and
advance construction material such as cement, concrete and admixtures.
b. Conduct/Familiarize the methods, procedures and formulas of different experiments on common
construction materials according to international standards such as ASTM & AASTHO.
Big Picture in Focus
ULO 2a. Demonstrate knowledge and understanding of the properties and behaviors of most
common and advance construction material such as cement, concrete and admixtures.
Metalanguage
This section deals with the study of different types and properties of construction materials such as
cement, concrete and admixtures.
Please proceed immediately to the “Essential Knowledge”.
Essential Knowledge
To perform the aforesaid big picture (unit learning outcomes) for the next two (2) weeks of the course,
you need to fully understand the following essential knowledge that will be laid down in the succeeding
pages. Please note that you are not limited to exclusively refer to these resources. Thus, you are
expected to utilize other books, research articles and other resources that are available in the
university’s library e.g. ebrary, search.proquest.com etc.
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INTRODUCTION: TYPES OF CEMENT USED IN CONSTRUCTION
What is cement?
Cement, one of the most important building materials, is a binding agent that sets and hardens to adhere to
building units such as stones, bricks, tiles, etc. Cement generally refers to a very fine powdery substance
chiefly made up of limestone (calcium), sand or clay (silicon), bauxite (aluminum) and iron ore, and may
include shells, chalk, marl, shale, clay, blast furnace slag, slate. The raw ingredients are processed in cement
manufacturing plants and heated to form a rock-hard substance, which is then ground into a fine powder to
be sold. Cement mixed with water causes a chemical reaction and forms a paste that sets and hardens to
bind individual structures of building materials.
Cement is an integral part of the urban infrastructure. It is used to make concrete as well as mortar, and to
secure the infrastructure by binding the building blocks. Concrete is made of cement, water, sand, and gravel
mixed in definite proportions, whereas mortar consists of cement, water, and lime aggregate. These are both
used to bind rocks, stones, bricks, and other building units, fill or seal any gaps, and to make decorative
patterns. Cement mixed with water silicates and aluminates, making a water repellant hardened mass that
is used for water-proofing.
TYPES OF CEMENT
Followings are the types of cement:
1. Ordinary Portland Cement (OPC)
2. Portland Pozzolana Cement (PPC)
3. Rapid Hardening Cement
4. Quick Setting Cement
5. Low Heat Cement
6. Sulphate Resisting Cement
7. Blast Furnace Cement
8. High Alumina Cement
9. White Cement
10. Colored Cement
11. Air Entraining Cement
12. Expansive Cement
13. Hydrophobic Cement
1. ORDINARY PORTLAND CEMENT (OPC)
In usual construction work, Ordinary Portland Cement is widely used. The composition of Ordinary Portland
Cement:
•
•
Argillaceous or silicates of alumina (clay and shale)
Calcareous or calcium carbonate (limestone, chalk, and marl)
Uses of Ordinary Portland Cement
•
It is used for general construction purposes.
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•
It is also used in most of the masonry works.
2. PORTLAND POZZOLAND CEMENT(PPC)
Pozzolans are natural or synthetic materials that contain silica in reactive forms. It reacts with calcium
hydroxide generated by hydrating cement to form additional cementations materials when it is finely
divided. The composition of Portland Pozzolana Cement:
•
•
•
OPC clinker
Gypsum
Pozzolanic Materials (Fly ash, volcanic ash, and Calcined clay or silica fumes.)
Uses of Portland Pozzolana Cement
•
•
•
•
PPC is usually used in hydraulic structures, marine structures, construction near the seashore, dam
construction etc.
It is also used in pre-stressed and post-tensioned concrete members.
As it gives a better surface finish, it is used in decorative and art structures.
It is also used in the manufacture of precast sewage pipes.
3. RAPID HARDINENING CEMENT
When finely grounded Tri-calcium silicate (C3S) is present in OPC with higher content, it gains strength
more quickly than OPC. This type of OPC is called Rapid Hardening Cement. It’s initial Setting Time 30
minutes and Final Setting Time 600 minutes.
Uses of Rapid Hardening Cement
•
•
Rapid hardening cement is mostly used where rapid construction is needed like the construction of
pavement.
It also gives high strength.
4. QUICK SETTING CEMENT
Quick setting cement is the cement which sets in a very short time. The initial setting time is 5 minutes and
the final setting time is 30 minutes. The composition of Quick Setting Cement:
•
•
•
Clinker
Aluminum sulphate (1% to 3% by weight of clinker)
The aluminum sulphate increase the hydration rate of silicate.
Uses of Quick Setting Cement
•
•
•
•
It is used in underwater construction.
It is also used in rainy & cold weather conditions.
It is used a higher temperature where water evaporates easily.
Used for anchoring or rock bolt mining and tunneling
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5. LOW HEAT CEMENT
It is a spatial type of cement which produce low heat of hydration during setting. Some chemical composition
of Ordinary Portland Cement is modified to reduce the heat of hydration. The chemical composition of low
heat cement:
•
•
A low percentage (5%) of tricalcium aluminate (C3A)
A higher percentage (46%) of declaim silicate (C2S).
Uses of Low Heat Cement
•
•
It is used for the construction of dam’s large footing, large raft slabs, and wind turbine plinths.
It is also used for the construction of chemical plants.
6. SULPHATE RESISTING CEMENT
Sulphate resisting cement is used to resist sulphate attacks in concrete. Due to the lower percentage
of Tricalcium aluminate, the production of calcium sulpho-aluminates gets reduced.
Uses of Sulphates resisting Cement
•
•
•
Construction in contact with soils or groundwater having more than 0.2% or 0.3 % g/l sulphate salts
respectively.
Concrete surfaces subjected to alternate wetting and drying such as bridge piers, concrete surface in
tidal zone, apron, Building near seacoast.
Effluent treatment plans, Chimney, Chemical industries, water storage, sumps, drainage works,
Cooling towers, Coastal protective works such as sea walls, breakwaters, tetrapods, etc.
7. BLAST FURNACE CEMENT
Portland cement clinker and graunlated blast furnace slag are intergrinded to make blast furnace cement.
Maximum 65 percent of the mixture could be comprised by blast furnace slag.
Uses of Blast Furnace Cement
•
•
It is highly sulphate resistant
Frequently used in seawater construction.
8. HIGH ALUMINA CEMENT
High Alumina cement is obtained by mixing calcining bauxite (it’s an aluminium ore) and ordinary lime with
clinker during the manufacture of OPC. In which the total amount of alumina content should not be lesser
than 32% and it should maintain the ratio by weight of alumina to the lime between 0.85 to 1.30.
Uses of High Alumina Cement
•
It is used where concrete structures are subjected to high temperatures like workshop, refractory,
foundries etc
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•
It also used where the concrete is subjected to frost and acidic action.
9. WHITE CEMENT
White cement is quite similar to Ordinary Portland Cement except for color. Amounts of iron oxide and
manganese oxide are low in White Cement. It is expensive then OPC so not economical for ordinary work.
Uses of White Cement
•
•
It is usually used in decorative work.
It can also use for traffic barriers, tile grouts, swimming pools, roof tiles patching materials and
terrazzo surfaces.
10. COLORED CEMENT
To make 5 to 10 percent of suitable pigments are grinded with OPC. Types of pigments are selected
according to the desired color.
Uses of Colored Cement
•
Colored cement is used for different decorative work.
11. AIR ENTRAINING CEMENT
It is seen that entrainment of air or formation of gas bubbles while applying cement increases resistance to
frost action, fire, scaling and other similar defects. Air-entraining cement is a special type of cement which
entrains tinny air bubbles in concrete.
It is produced by grinding minute air entertaining materials with clinker by adding some resinous materials
e.g. vinsol resin to ordinary portland cement.
When the water in concrete gets frizzed due to low temperature, it expands. When air-entraining cement,
the air voids in concrete provides space for water to expand without cracking concrete. But this type of
cement does not provide high strength in concrete.
Uses of Air-Entraining Cement
•
•
•
Especially it is used in areas where the temperature is very low.
It also resists Sulphate attack.
It is used where the de-icing chemical is used.
12. EXPANSIVE CEMENT
In the hydration process, the expansive cement expands its volume. It can be possible to overcome shrinkage
loss by using expansive cement.
There are three types of expansive cement:
1. K Type expansive cement
2. M Type expansive cement
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3. S Type expansive cement
K Type expansive cement
Raw materials of these types of cement
•
•
•
•
Portland cement
Anhydrous tetracalcium trialuminate sulfate (C4A3S)
Calcium sulfate (CaSO4)
Lime (CaO).
M Type Expansive Cement
Raw materials of these types of cement
1. Portland cement clinkers
2. Calcium sulfate.
S Type Expansive Cement
Raw materials of these types of cement
1. Portland cement clinkers
2. Calcium sulfate (High amount)
•
Tricalcium aluminate (C3A) (High amount)
Uses of Expansive cement
•
•
•
It is used in the construction of the pre-stressed concrete component.
It is also used for sealing joints and grouting anchor bolt.
In the construction of different hydraulic structures, this type of cement is used.
13. HYDROPHOBIC CEMENT
To resist the hydration process in the transportation or storage stage, clinkers are grinded with water
repellent film substance such as Oleic Acid or Stearic Acid. These chemicals form a layer on the cement
particle and do not allow water to mix and start the hydration process. When cement and aggregate are
thoroughly mixed in the mixer, protective layers break and start normal hydration with some airentrainment which increases workability.
Uses of Hydrophobic Cement
•
•
Usually, it is used in the construction of water structures such as dams, spillways, or other submerged
structures.
It is also used in the construction of underground structures like tunnel etc.
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8 Main Cement Ingredients & Their Functions
Cement, as a binding material, is a very important building material. Almost every construction work
requires cement. Therefore, the composition of cement is a matter of great interest to engineers. For
understanding cement composition, one must know the functionality of Cement ingredients. By altering
the amount of an ingredient during cement production, one can achieve the desired cement quality.
Ingredients of Cement
Composition of Cement
There are eight major ingredients of cement. The following image is showing the ingredients of cement:
The general percentage of these ingredients in cement is given below:
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Ingredient
Percentage in cement
Lime
60-65
Silica
17-25
Alumina
3-8
Magnesia
1-3
Iron oxide
0.5-6
Calcium Sulfate
0.1-0.5
Sulfur Trioxide
1-3
Alkaline
0-1
Functions of Cement Ingredients
The main features of these cement ingredients along with their functions and usefulness or harmfulness
are given below:
1. Lime: Lime is calcium oxide or calcium hydroxide.
o Presence of lime in a sufficient quantity is required to form silicates and aluminates of calcium.
o Deficiency in lime reduces the strength of property to the cement.
o Deficiency in lime causes cement to set quickly.
o Excess lime makes cement unsound.
o Excessive presence of lime cause cement to expand and disintegrate.
2. Silica: Silicon dioxide is known as silica, chemical formula SiO2.
o Sufficient quantity of silica should be present in cement to dicalcium and tricalcium silicate.
o Silica imparts strength to cement.
o Silica usually presents to the extent of about 30 percent cement.
3. Alumina: Alumina is Aluminum oxide. The chemical formula is Al2O3.
o Alumina imparts quick setting property to the cement.
o Clinkering temperature is lowered by the presence of the requisite quantity of alumina.
o Excess alumina weakens the cement.
4. Magnesia: Magnesium Oxide. Chemical formula is MgO.
o Magnesia should not be present more than 2% in cement.
o Excess magnesia will reduce the strength of the cement.
5. Iron oxide: Chemical formula is Fe2O3.
o Iron oxide imparts color to cement.
o It acts as a flux.
o At a very high temperature, it imparts into the chemical reaction with calcium and aluminum to
form tricalcium alumino-ferrite.
o Tricalcium alumino-ferrite imparts hardness and strength to cement.
6. Calcium Sulfate: Chemical formula is CaSO4
o This is present in cement in the form of gypsum(CaSO4.2H2O)
o It slows down or retards the setting action of cement.
7. Sulfur Trioxide: Chemical formula is SO3
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Should not be present more than 2%.
Excess Sulfur Trioxide causes cement to unsound.
8. Alkaline:
o Should not be present more than 1%.
o Excess Alkaline matter causes efflorescence.
o
o
Properties of Cement- Physical & Chemical
Cement, a popular binding material, is a very important civil engineering material. This article concerns
the physical and chemical properties of cement, as well as the methods to test cement properties.
Physical Properties of Cement
Different blends of cement used in construction are characterized by their physical properties. Some
key parameters control the quality of cement. The physical properties of good cement are based on:
•
•
•
•
•
•
•
•
•
Fineness of cement
Soundness
Consistency
Strength
Setting time
Heat of hydration
Loss of ignition
Bulk density
Specific gravity (Relative density)
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These physical properties are discussed in details in the following segment. Also, you will find the test
names associated with these physical properties.
Fineness of Cement
The size of the particles of the cement is its fineness. The required fineness of good cement is achieved
through grinding the clinker in the last step of cement production process. As hydration rate of cement
is directly related to the cement particle size, fineness of cement is very important.
Soundness of Cement
Soundness refers to the ability of cement to not shrink upon hardening. Good quality cement retains its
volume after setting without delayed expansion, which is caused by excessive free lime and magnesia.
Tests:
Unsoundness of cement may appear after several years, so tests for ensuring soundness must be able
to determine that potential.
•
•
Le Chatelier Test
This method, done by using Le Chatelier Apparatus, tests the expansion of cement due to lime. Cement
paste (normal consistency) is taken between glass slides and submerged in water for 24 hours at
20+1°C. It is taken out to measure the distance between the indicators and then returned under water,
brought to boil in 25-30 mins and boiled for an hour. After cooling the device, the distance between
indicator points is measured again. In a good quality cement, the distance should not exceed 10 mm.
Autoclave Test
Cement paste (of normal consistency) is placed in an autoclave (high-pressure steam vessel) and slowly
brought to 2.03 MPa, and then kept there for 3 hours. The change in length of the specimen (after
gradually bringing the autoclave to room temperature and pressure) is measured and expressed in
percentage. The requirement for good quality cement is a maximum of 0.80% autoclave expansion.
Standard autoclave test: AASHTO T 107 and ASTM C 151: Autoclave Expansion of Portland Cement.
Consistency of Cement
The ability of cement paste to flow is consistency.
It is measured by Vicat Test.
In Vicat Test Cement paste of normal consistency is taken in the Vicat Apparatus. The plunger of
the appar atus is brought down to touch the top surface of the cement. The plunger will penetrate
the cement up to a certain depth depending on the consistency. A cement is said to have a normal
consistency when the plunger penetrates 10±1 mm.
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Strength of Cement
Three types of strength of cement are measured – compressive, tensile and flexural. Various factors
affect the strength, such as water-cement ratio, cement-fine aggregate ratio, curing conditions, size and
shape of a specimen, the manner of molding and mixing, loading conditions and age. While testing the
strength, the following should be considered:
•
•
•
Cement mortar strength and cement concrete strength are not directly related. Cement strength is
merely a quality control measure.
The tests of strength are performed on cement mortar mix, not on cement paste.
Cement gains strength over time, so the specific time of performing the test should be mentioned.
Compressive Strength
It is the most common strength test. A test specimen (50mm) is taken and subjected to a compressive
load until failure. The loading sequence must be within 20 seconds and 80 seconds.
Standard tests:
i.
ii.
AASHTO T 106 and ASTM C 109: Compressive Strength of Hydraulic Cement Mortars (Using 50-mm or
2-in. Cube Specimens)
ASTM C 349: Compressive Strength of Hydraulic Cement Mortars (Using Portions of Prisms Broken in
Flexure)
Tensile strength
Though this test used to be common during the early years of cement production, now it does not offer
any useful information about the properties of cement.
Flexural strength
This is actually a measure of tensile strength in bending. The test is performed in a 40 x40 x 160 mm
cement mortar beam, which is loaded at its center point until failure.
Standard test:
i.
ASTM C 348: Flexural Strength of Hydraulic Cement Mortars
Setting Time of Cement
Cement sets and hardens when water is added. This setting time can vary depending on multiple factors,
such as fineness of cement, cement-water ratio, chemical content, and admixtures. Cement used in
construction should have an initial setting time that is not too low and a final setting time not too high.
Hence, two setting times are measured:
•
Initial set: When the paste begins to stiffen noticeably (typically occurs within 30-45 minutes)
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•
Final set: When the cement hardens, being able to sustain some load (occurs below 10 hours)
Again, setting time can also be an indicator of hydration rate.
Standard Tests:
i.
ii.
iii.
AASHTO T 131 and ASTM C 191: Time of Setting of Hydraulic Cement by Vicat Needle
AASHTO T 154: Time of Setting of Hydraulic Cement by Gillmore Needles
ASTM C 266: Time of Setting of Hydraulic-Cement Paste by Gillmore Needles
Heat of Hydration
When water is added to cement, the reaction that takes place is called hydration. Hydration generates
heat, which can affect the quality of the cement and also be beneficial in maintaining curing temperature
during cold weather. On the other hand, when heat generation is high, especially in large structures, it
may cause undesired stress. The heat of hydration is affected most by C3S and C3A present in cement,
and also by water-cement ratio, fineness and curing temperature. The heat of hydration of Portland
cement is calculated by determining the difference between the dry and the partially hydrated cement
(obtained by comparing these at 7th and 28th days).
Standard Test:
ASTM C 186: Heat of Hydration of Hydraulic Cement
Loss of Ignition
Heating a cement sample at 900 - 1000°C (that is, until a constant weight is obtained) causes weight
loss. This loss of weight upon heating is calculated as loss of ignition. Improper and prolonged storage
or adulteration during transport or transfer may lead to pre-hydration and carbonation, both of which
might be indicated by increased loss of ignition.
Standard Test:
AASHTO T 105 and ASTM C 114: Chemical Analysis of Hydraulic Cement
Bulk density
When cement is mixed with water, the water replaces areas where there would normally be air. Because
of that, the bulk density of cement is not very important. Cement has a varying range of density
depending on the cement composition percentage. The density of cement may be anywhere from 62 to
78 pounds per cubic foot.
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Specific Gravity (Relative Density)
Specific gravity is generally used in mixture proportioning calculations. Portland cement has a specific
gravity of 3.15, but other types of cement (for example, portland-blast-furnace-slag and portlandpozzolan cement) may have specific gravities of about 2.90.
Standard Test:
AASHTO T 133 and ASTM C 188: Density of Hydraulic Cement
Chemical Properties of Cement
The raw materials for cement production are limestone (calcium), sand or clay (silicon), bauxite
(aluminum) and iron ore, and may include shells, chalk, marl, shale, clay, blast furnace slag, slate.
Chemical analysis of cement raw materials provides insight into the chemical properties of cement.
1. Tricalcium aluminate (C3A)
Low content of C3A makes the cement sulfate-resistant. Gypsum reduces the hydration of C3A,
which liberates a lot of heat in the early stages of hydration. C3A does not provide any more
than a little amount of strength.
Type I cement: contains up to 3.5% SO3 (in cement having more than 8% C3A)
Type II cement: contains up to 3% SO3 (in cement having less than 8% C3A)
2. Tricalcium silicate (C3S)
C3S causes rapid hydration as well as hardening and is responsible for the cement’s early
strength gain an initial setting.
3. Dicalcium silicate (C2S)
As opposed to tricalcium silicate, which helps early strength gain, dicalcium silicate in cement
helps the strength gain after one week.
4. Ferrite (C4AF)
Ferrite is a fluxing agent. It reduces the melting temperature of the raw materials in the kiln
from 3,000°F to 2,600°F. Though it hydrates rapidly, it does not contribute much to the strength
of the cement.
5. Magnesia (MgO)
The manufacturing process of Portland cement uses magnesia as a raw material in dry process
plants. An excess amount of magnesia may make the cement unsound and expansive, but a little
amount of it can add strength to the cement. Production of MgO-based cement also causes less
CO2 emission. All cement is limited to a content of 6% MgO.
6. Sulphur trioxide
Sulfur trioxide in excess amount can make cement unsound.
7. Iron oxide/ Ferric oxide
Aside from adding strength and hardness, iron oxide or ferric oxide is mainly responsible for
the color of the cement.
8. Alkalis
The amounts of potassium oxide (K2O) and sodium oxide (Na2O) determine the alkali content of
the cement. Cement containing large amounts of alkali can cause some difficulty in regulating
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the setting time of cement. Low alkali cement, when used with calcium chloride in concrete, can
cause discoloration. In slag-lime cement, ground granulated blast furnace slag is not hydraulic
on its own but is "activated" by addition of alkalis. There is an optional limit in total alkali
content of 0.60%, calculated by the equation Na2O + 0.658 K2O.
9. Free lime
Free lime, which is sometimes present in cement, may cause expansion.
10. Silica fumes
Silica fume is added to cement concrete in order to improve a variety of properties, especially
compressive strength, abrasion resistance and bond strength. Though setting time is prolonged
by the addition of silica fume, it can grant exceptionally high strength. Hence, Portland cement
containing 5-20% silica fume is usually produced for Portland cement projects that require high
strength.
11. Alumina
Cement containing high alumina has the ability to withstand frigid temperatures since alumina
is chemical-resistant. It also quickens the setting but weakens the cement.
CEMENT MANUFACTURING PROCESS
Stage of Cement Manufacture
There are six main stages of cement manufacturing process.
Stage 1: Raw Material Extraction/Quarry
The raw cement ingredients needed for cement production are limestone (calcium), sand and clay
(silicon, aluminum, iron), shale, fly ash, mill scale and bauxite. The ore rocks are quarried and crushed
to smaller pieces of about 6 inches. Secondary crushers or hammer mills then reduce them to even
smaller size of 3 inches. After that, the ingredients are prepared for pyro processing.
Stage 2: Grinding, Proportioning and Blending
The crushed raw ingredients are made ready for the cement making process in the kiln by combining
them with additives and grinding them to ensure a fine homogenous mixture. The composition of
cement is proportioned here depending on the desired properties of the cement. Generally, limestone
is 80% and remaining 20% is the clay. In the cement plant, the raw mix is dried (moisture content
reduced to less than 1%); heavy wheel type rollers and rotating tables blend the raw mix and then the
roller crushes it to a fine powder to be stored in silos and fed to the kiln.
Stage 3: Pre-Heating Raw Material
A pre-heating chamber consists of a series of cyclones that utilizes the hot gases produced from the kiln
in order to reduce energy consumption and make the cement making process more environmentfriendly. The raw materials are passed through here and turned into oxides to be burned in the kiln.
Stage 4: Kiln Phase
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The kiln phase is the principal stage of the cement production process. Here, clinker is produced from
the raw mix through a series of chemical reactions between calcium and silicon dioxide compounds.
Though the process is complex, the events of the clinker production can be written in the following
sequence:
1.
2.
3.
4.
5.
6.
7.
8.
Evaporation of free water
Evolution of combined water in the argillaceous components
Calcination of the calcium carbonate (CaCO3) to calcium oxide (CaO)
Reaction of CaO with silica to form dicalcium silicate
Reaction of CaO with the aluminum and iron-bearing constituents to form the liquid phase
Formation of the clinker nodules
Evaporation of volatile constituents (e. g., sodium, potassium, chlorides, and sulfates)
Reaction of excess CaO with dicalcium silicate to form tricalcium silicate
The above events can be condensed into four major stages based on the change of temperature inside
the kiln:
1. 100°C (212°F): Evaporation of free water
2. 100°C (212°F)-430°C (800°F): Dehydration and formation of oxides of silicon, aluminum, and
iron
3. 900°C (1650°F)-982°C (1800°F): CO2 is evolved and CaO is produced through calcination
4. 1510°C (2750°F): Cement clinker is formed
The kiln is angled by 3 degrees to the horizontal to allow the material to pass through it, over a period
of 20 to 30 minutes. By the time the raw-mix reaches the lower part of the kiln, clinker forms and comes
out of the kiln in marble-sized nodules.
Stage 5: Cooling and final grinding
After exiting the kiln, the clinker is rapidly cooled down from 2000°C to 100°C-200°C by passing air
over it. At this stage, different additives are combined with the clinker to be ground in order to produce
the final product, cement. Gypsum, added to and ground with clinker, regulates the setting time and
gives the most important property of cement, compressive strength. It also prevents agglomeration and
coating of the powder at the surface of balls and mill wall. Some organic substances, such as
Triethanolamine (used at 0.1 wt.%), are added as grinding aids to avoid powder agglomeration. Other
additives sometimes used are ethylene glycol, oleic acid and dodecyl-benzene sulphonate.
The heat produced by the clinker is circulated back to the kiln to save energy. The last stage of
making cement is the final grinding process. In the cement plant, there are rotating drums fitted with
steel balls. Clinker, after being cooled, is transferred to these rotating drums and ground into such a fine
powder that each pound of it contains 150 billion grains. This powder is the final product, cement.
Stage 6: Packing and Shipping
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Cement is conveyed from grinding mills to silos (large storage tanks) where it is packed in 20-40 kg
bags. Most of the product is shipped in bulk quantities by trucks, trains or ships, and only a small amount
is packed for customers who need small quantities.
Some of the numerous functions of cement are given below.
1.
2.
3.
4.
5.
6.
7.
8.
9.
It is used in mortar for plastering, masonry work, pointing, etc.
It is used for making joints for drains and pipes.
It is used for water tightness of structure.
It is used in concrete for laying floors, roofs and constructing lintels, beams, stairs, pillars etc.
It is used where a hard surface is required for the protection of exposed surfaces of structures
against the destructive agents of the weather and certain organic or inorganic chemicals.
It is used for precast pipes manufacturing, piles, fencing posts etc.
It is used in the construction of important engineering structures such as bridges,
culverts, dams, tunnels, lighthouses etc.
It is used in the preparation of foundations, watertight floors, footpaths etc.
It is employed for the construction of wells, water tanks, tennis courts, lamp posts, telephone
cabins, roads etc.
Raw material ingredients used for manufacturing of Portland Cement are:
1. Calcareous Materials: Calcareous Materials are compounds of calcium and magnesium.
Limestones are a common calcareous material used in manufacturing cement.
2. Argillaceous Materials: Argillaceous Materials are mainly silica, alumina, and oxides of iron.
Clay and shale are the common argillaceous material used as cement ingredient in the process
of manufacturing cement.
Properties of Good Cement
It is always desirable to use the best cement in constructions. Therefore, the properties of a
cement must be investigated. Although desirable cement properties may vary depending on the type of
construction, generally a good cement possesses following properties (which depend upon
its composition, thoroughness of burning and fineness of grinding).
•
•
•
•
•
•
Provides strength to masonry.
Stiffens or hardens early.
Possesses good plasticity.
An excellent building material.
Easily workable.
Good moisture-resistant.
Proper field tests and laboratory tests should be done to ensure the qualities of the cement.
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HYDRAULIC CEMENT BY VICAT NEEDLE
REFERENCED STANDARD: ASTM C 191-42/ AASHTO T 131-93
Hydraulic Cement is a product used to stop water and leaks in concrete and masonry structures. It is a type of
cement, similar to mortar, that sets extremely fast and hardens after it has been mixed with water. Hydraulic
cement is used widely in the construction industry sealing structures below grade and in situations where
structures can be affected or submerged in water.
Vicat's Apparatus is used to find out the consistency, initial setting time and final setting time of the cement. In
the normal consistency test, we have to find out the amount of water to be added to the cement to form a cement
paste of normal consistency.
Vicat's Apparatus consists of an arrangement to hold the plunger of 10 mm diameter and two other needles which
are made to freely fall into a mound filled with the cement paste and the amount of penetration of the needles of
plunder can be noted using the vertical graduations from 0 mm to 50 mm.
Normal Consistency Test (ASTM 187-86 re approved 1991)
In the acceptance test for cement, the water content is regulated by bringing the paste to a standard condition of
wetness. This is called “Normal Consistency.”
Cement of normal consistency is required to measure setting time.
Definition of Terms:
Consistency – refers to the thickness or the viscosity of the cement paste.
Cement Paste - the viscous mass obtained by mixing cement with water.
Standard Cement Paste - is the cement paste for which the 10mm diameter plunger in a standard VICAT test
penetrates to such an extent that its distance from the bottom is 5-7mm.
Normal Consistency
•
•
•
•
•
•
A standard measure of plasticity of a cement paste. A paste has normal consistency when a Vicat plunger
(10 mm in diameter) penetrates 10 ±1 mm in 30 sec under its own weight. The
required water/cement ratio is determined by trial and error.
It is the thickness or the viscosity of the standard paste and is expressed as the percentage of weight of
water.
The quantity of mixing water to form a standard paste for setting and soundness test.
It depends upon the compound composition and fineness of cement.
About 24%~30% (by weight) for Portland cement.
Test Specifications:
•
•
Temperature & Humidity
o The temperature of the air in the vicinity should be between 20-27.5 °C. The temperature of the
mixing water should be 23±2 °C. The relative humidity of the laboratory should not be less than
50%.
Amount of Cement
o Amount of cement required for the test according to various specifications are mentioned below.
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•
▪ BS-12 = 500gm
▪ ASTM C-187 = 650gm
Mixing Time
o The cement paste must be properly mixed and placed in the test specimen within a maximum
time of 4±1/4 min from the instant when cement and water were initially brought in contact.
Set Time Test (ASTM C 191 - 92)
Setting time is the term used to describe the stiffening of the cement paste, and it refers to a change from a fluid
state to a rigid state.
The knowledge of the setting time of the cement is always helpful in deciding the time duration to mix, transport,
place and compact the concrete effectively.
Definition of Terms:
Setting
•
In the setting process, very little chemical reaction takes place. It only includes the shape acquisition due
to evaporation of water. During the setting process the cement remains in the fluid or the semi-fluid state
and there is very little or no gain in strength. Finer the cement particles more will be the hydration and
therefore it will lead to quick settlement.
Hardening
•
Hardening is the rate of gain of strength due to the chemical reaction. It also refers to the strength of the
concrete after a specified interval of time.
Time of Initial Set
•
•
•
The time elapsed between the initial contact of cement and water and the time when a 1mm2 crosssection needle gives a reading between 4-7mm from the bottom in a standard Vicat apparatus is known
as initial setting time of that particular cement paste.
The time at which the concrete can no longer be properly mixed, finished or compacted. (Represented by
a Vicat needle (1mm in diameter) penetration of 25 mm or less). ASTM C150 prescribes a minimum initial
setting time of 60 minute for Portland cement. (45 minutes (BS12:1978))
We always prefer a larger initial setting time so that we can mix, transport and place the concrete easily.
According to ASTM specifications, the initial setting time shall not be less than 45 min but in the field, we
prefer an initial setting time not less than 90 min.
Time of Final Set
•
•
•
It is the time elapsed between the initial contact of cement and water and the time when the smaller
needle (1mm2 cross-section and 0.5mm deep) completely penetrates into the paste and the outer metal
attachment of 5mm diameter does not leave an impression on the cement paste.
The time required for the cement to harden to a point where it can sustain some load. (Represented by
no penetration of Vicat needle, the needle makes an impression and the cutting edge fails). ASTM C150
prescribes a maximum final setting time of 10-12 hours for Portland cement.
A smaller value of the final setting time is always preferred in order to avoid large expenditures on the
formwork. According to most of the specifications, the final setting time shall not be greater than 10hrs
and shall not be less than (90 + 1.2 x (initial setting time)) min.
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Factors affecting setting time:
•
•
•
•
Temperature and humidity
Amount of water (w/c)
Chemical composition of cement
Fineness of cement (finer cement → faster setting)
COMMON CONCRETE MIX PROPORTION AND ITS APPLICATION
What is Concrete?
Concrete, an artificial stone-like mass, is the composite material that is created by mixing binding
material (cement or lime) along with the aggregate (sand, gravel, stone, brick chips, etc.), water,
admixtures, etc in specific proportions. The strength and quality are dependent on the mixing
proportions.
The formula for producing concrete from its ingredients can be presented in the following equation:
Concrete = Binding Material + Fine & Coarse Aggregate + Water + Admixture (optional)
Concrete is a very necessary and useful material for construction work. Once all the ingredients cement, aggregate, and water unit of measurement mixed inside the required proportions,
the cement and water begin a reaction with one another to bind themselves into a hardened mass. This
hardens rock-like
mass
is
the
concrete.
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Concrete
Concrete is powerful, easy to create and could be formed into varied shapes and sizes. Besides that, it is
reasonable, low cost and is instantly mixed. It is designed to allow reliable and high-quality fast-track
construction. Structures designed with the concrete unit of measurement plenty of durable and should
be designed to face up to earthquakes, hurricanes, typhoons, and tornadoes. This is an incredible
advancement. With all the scientific advances there are in this world, there still has not been the way of
preventing nature's injury.
Composition of Basic Concrete Mix
There are four basic ingredients within the concrete mix:
•
•
•
•
Binding materials like cement or lime
Aggregates or Inert Materials
o Fine aggregate (sand)
o Coarse aggregate (stone chips, brick chips)
Water
Admixture (e.g. Pozzolana)
Description of the concrete ingredients is given below.
Binding Materials
Binding material is the main element of a concrete mix. Cement is the most commonly used binding
material. Lime could also be used. When water is mixed with the cement, a paste is created that coats
the aggregates within the mix. The paste hardens, binds the aggregates and form a stone-like substance.
Aggregates
Sand is the fine mixture. Gravel or crushed stone is the coarse mixture in most mixes.
Water
Water is required to with chemicals react with the cement (hydration) and to supply workability with
the concrete. The number of water within the combine in pounds compared with the number of cement
is named the water/cement quantitative relation. The lower the w/c quantitative relation, the stronger
the concrete. (Higher strength, less permeability)
Types of Concrete Mix
Concrete is employed for various projects starting from little homemade comes to large subject field
buildings and structures. It is used for sidewalks, basements, floors, walls, and pillars at the side of
several alternative uses. Many sorts of concrete are utilized in the development works.
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Based on the variations in materials and purposes, concrete can be classified into three basic categories1. Lime Concrete
2. Cement Concrete
3. Reinforced Cement Concretes
In general, there are four concrete sorts to settle on from counting on the work being done. Such as1.
2.
3.
4.
Dry Ready Mix
Ready Mix
Bulk Dry Materials
Transit Mix
There are other various types of concrete for different applications that are created by changing the
proportions of the main ingredients. Such as:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Regular Concrete
High-strength Concrete
Stamped Concrete
High-Performance Concrete
Self-consolidating Concretes
Vacuum Concrete
Shotcrete
Roller-Compacted concrete
Glass Concrete
Asphalt Concrete
Rapid Strength Concrete
Polymer Concrete
Limecrete
Light-Transmitting Concrete
Descriptions of these types of concrete are discussed below:
Lime Concrete
Lime concrete uses lime as the binding material. Lime is usually mixed with surki and khoa or stones in
the proportion 1:2:5 unless otherwise specified. The khoa or stones are soaked in water before mixing.
Lime concrete is used mainly in foundation and terrace roofing.
Cement Concrete
Most engineering construction uses cement concrete composites as the main building material. It
consists of cement, sand, brick chips or stone chips of the required size. The usual proportion is 1:2:4
or 1:3:6. After mixing the required amounts of materials, the concrete mix is cured with water for 28
days for proper strength building.
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Reinforced Cement Concretes
For enhancing the tensile strength of concrete, steel reinforcements are added. Sometimes, RCC is
prestressed under compression to eliminate or reduce tensile stresses. The resulting concrete is known
as Prestressed Concrete.
Dry Ready Mix
This is the combination that may be found at the most home improvement and hardware stores. It
comes in baggage typically starting from sixty to eighty pounds. Dry ready mix is simple to combine and
this is often the combination that almost all homemade comes would require. The tools needed for the
mixture are a bucket or cart, shovel or hoe, trowel and a measured quantity of water.
Ready Mix
The distinction between dry ready mix and ready-mix concrete is that the water is already
supplementary to ready combine. This concrete comes pre-mixed and is for larger homemade comes or
for people who do not need to combine their own concrete. It is typically brought in an exceedingly little
trailer, typically with an intermixture drum connected to stay it dampish and mixed. The ready combine
is usually costlier and might be troublesome to search out. It additionally should be used quickly as an
alternative it will set while not unfolding properly.
Bulk Dry Materials
It is price effective to purchase dry materials in bulk. This may let the project be custom-built to the
particular wants and usage of the concrete. The drawback of shopping for in bulk is that there will be
much space for the materials to be kept before getting used. The materials will over probably be
delivered to the positioning.
Transit Mix
This is the mix that almost all cast-in-place concrete comes can use. it is typically trucked in using
concrete trucks that have the massive drum that keeps the concrete from setting up whereas in transit.
It permits for one continuous pour so fewer seams and stronger concrete overall. For big comes, transit
combine is far additional value effective than getting bulk materials or ready-mix since in each those
the workforce to combine the concrete would get to be patterned into the value.
Regular Concrete
The most common type used is the regular concrete that is referred to as traditional weight concrete or
traditional strength concrete. This pertains to the concrete that is promptly on the market within the
retailer’s marketplace for personal and residential usage. This includes usage directions that are
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written within the packaging of the product. It utilizes sand and different materials to function
aggregates and is consolidated in temporary vessels.
High-strength Concrete
High strength concrete combine possesses compressive strength that is over six thousand pounds per
area unit. This can be processed by lowering the water-cement quantitative relation to a minimum of
0.35 or lower. The low water-cement quantitative relation makes this sort of cementless feasible. so as
to combat this weakness, superplasticizers are other to the present concrete combine.
Stamped Concrete
Stamped concrete is a subject area concrete wherever realistic patterns almost like natural stones,
granites, and tiles will be obtained by inserting the impression of skilled stamping pads. This stamping
is applied on the concrete once it is in its plastic condition. totally different coloring stains and texture
work can finally provide an end that's terribly almost like costlier natural stones. A high aesthetic look
will be obtained from a sealed end economically. This is often utilized in the development of driveways,
interior floors, and patios.
High-Performance Concrete
High-performance concrete refers to a freshly developed concrete combine that has properties that are
a notch higher compared to regular concrete mixes. This includes increased strength, durability, and
workability, simplicity of usage, compaction while not segregation, long-run mechanical properties,
porosity, density, toughness, and volume stability. Air-entrained agents may be utilized in order to
customize this concrete combine for severe environments.
Self-Consolidating Concrete
The concrete combine once placed can compact by its own weight is considered self-consolidated
concrete. No vibration should be provided for an equivalent individually. This combine has higher
workability. The slumping price is going to be between 650 and 750. This concrete because of its higher
workability is named as flowing concrete. The areas wherever there is thick reinforcement, self –
consolidating concrete works best.
Vacuum Concretes
Concrete with water content quite the desired amount is poured into the formwork. The surplus water
is then removed out with the assistance of an air pump while not looking forward to the concrete to
endure setting. Thus, the concrete structure or the platform is going to be able to use earlier in
comparison with traditional construction technique. These concretes can attain their 28 days
compressive strength inside an amount of 10 days and therefore the crushing strength of this structure
is 25 you bigger compared with the standard concrete sorts.
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Shotcrete
Shotcreting refers to a method within which compressed air forces mortar or concrete through a tube
and tap onto a surface at a high speed and forms structural or non-structural parts of
buildings. Shotcrete is currently applied to the wet-mix method and has gained universal acceptance in
several countries. In wet-mix application cement, aggregate, admixture, and water are mixed along
before being wired through a hose and atmospherically designed. On the opposite hand, in dry-mix
applications cement, aggregate, and admixture are mixed along, sent pneumatically through a tube so,
at the tap via a water ring, water is injected equally throughout the combination because it is being
designed.
Roller-Compacted Concrete
This type of concrete has placed and compacted with the assistance of earthmoving instrumentality like
serious rollers. This concrete is principally utilized in excavation and filling wants. These concretes have
cement content in lesser quantity and stuffed for the realm necessary. once compaction, these concretes
give high density and eventually cure into a powerful monolithic block.
Glass Concrete
The recycled glass may be used as aggregates in concrete. Thus, we tend to get concrete of recent times,
the glass concrete. This concrete can increase the aesthetic appeal of the concrete. They can give long
strength and higher thermal insulation.
Asphalt Concrete
Asphalt concrete may be a material, the mixture of aggregates and asphalts ordinarily accustomed
surface roads, parking tons, airports, yet because of the core of mound dams. Asphalt concrete is known
as asphalt, blacktop, or pavement and tarmac or bitumen, macadam or rolled asphalt in the other
countries.
Rapid Strength Concrete
As the name implies these concretes can acquire strength with few hours once its manufacture.
Therefore, the formwork removal is created simple and the building construction is roofed quickly.
These have a widespread application within the road repairs, as they'll be reused once some hours.
Polymer Concrete
In polymer concrete, the aggregates are restrained with the polymer rather than cement. The assembly
of polymer concrete can facilitate within the reduction of volume of voids within the mixture. This may
cut back the quantity of polymer that is necessary to bind the aggregates used. Hence, the aggregates
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are ranked and mixed consequently to attain minimum void. This kind of concrete has totally different
classes:
•
•
•
Polymer Impregnated Concrete
Polymer cement concrete
Partially Impregnated
Limecrete
The cement is replaced by lime during this concrete kind. The most application of this product is on
floors, domes, likewise as vaults. These not like cement have several environmental and health
advantages. These products are renewable and simply clean.
Light-Transmitting Concrete
Concrete that has a density lesser than 1920kg/m3 are classified as light-weight concrete. The
utilization of lightweight aggregates in a concrete style can provide us lightweight aggregates.
Aggregates are the vital part that contributes to the density of the concrete. The samples of lightweight
aggregates are stone, perlites, and scoria. The lightweight concrete is applied for the protection of the
steel structures and is used for the development of the long-span bridge decks. These are used for the
development of the building blocks.
Main Properties of Concrete for Construction
Concrete is a mixture of several materials. At the hardened state, this heterogeneous material becomes
stone-like mass. The extensive use of concrete in the construction field has made it a material of huge
concern for engineers. To participate in the vast uses of concrete an engineer must know its properties.
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PROPERTIES OF CONCRETE:
1.Strength
Strength of concrete are of the following types:
a.
b.
c.
d.
Compressive strength
Tensile strength
Flexural strength
Shear strength
a. Compressive Strength
Two types of test specimens are used in Bangladesh -(1) Cube and (2) Cylinder.
The cube specimens of concrete of the desired proportion are cast in steel or cast iron molds, normally
6-inch cube. The standard cylinder specimen of concrete is 6 inch in diameter and 12 inches in height
and cast in a mold generally made of cast iron;
Standard cubes and cylinders are tested at prescribed ages, generally, 28 days, with additional tests
often made at 1, 3, and 7 days. The specimens are tested for crushing strength under a testing
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machine. The cube tests give much greater values of crushing strength, usually 20 to 30 % more than
those given by cylinders.
According to British standard, the strength of a cylinder specimen is equal to three-quarters of the
strength of the cube specimen.
Figure: Cube and Cylinder Specimens for Compression Strength Testing.
Effect of age on concrete strength:
Concrete attains strength with time. Ordinary cement concrete gains above 70 to 75% of its final
strength within 28 days and about 90 to 95 % in the course of one year. It is often desirable to check
the suitability of a concrete long before the results of the 28-day test are available. When no specific
data on the materials used in making concrete are available, the 28-day strength may be assumed to be
1.5 times of the 7 days’ strength. Tests have shown that for concrete made with ordinary Portland
cement the ratio of the 28 days to 7 days’ strength generally lies between 1.3 to 1.7, and the majority of
the results fall above 1.5. The extrapolation of 28 days’ strength from the 7 days’ strength is, therefore
quite reliable;
The rate of gain of strength of the different type of cement concretes are shown in the figure below
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b. Tensile strength
Concrete is very weak in tension. The tensile strength of ordinary concrete ranges from about 7 to 10
percent of the compressive strength.
c. Flexural strength
The flexural strength of plain concrete is almost wholly dependent upon the tensile strength. However,
experiments show that the modulus of rupture is considerably greater than the strength in tension.
d. Shear strength
It is the real determining factor in the compressive strength of short columns. The average strength of
concrete in direct shear varies from about half of the compressive strength for rich mixtures to about
0.8 of the compressive strength for lean mixtures.
2.Workability
The strength of concrete of a given mix proportion is very seriously affected by the degree of its
compaction. It is therefore vital that the consistency of the mix be such that the concrete can be
transported, placed and finished sufficiently easily and without segregation. A concrete satisfying these
conditions is said to be workable.
Factors affecting the workability of concrete are:
▪
▪
▪
▪
▪
▪
▪
Water Content
Mix Proportions
Size of Aggregates
Shape of Aggregates
Grading of Aggregates
Surface Texture of Aggregates
Use of Admixtures
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▪
▪
▪
Use of Supplementary Cementitious Materials
Time
Temperature
Usually, Slump test is done to indirectly determine the workability of a concrete mix.
3.Elastic Properties
Concrete is not perfectly elastic for any range of loading, an appreciable permanent setting taking place
for even low loads. The deformation is not proportional to the stress at any stage of loading. The elastic
properties of concrete vary with the richness of the mixture and with the intensity of the stress. They
also vary with the age of concrete.
4.Durability
Durability is the property of concrete to withstand the condition for which it has been designed, without
deterioration over a period of years. Lack of durability can be caused by external agents arising from
the environment or by internal agents within the concrete.
Causes can be categorized as physical, mechanical and chemical.
Physical cause arises from the action of frost and from differences between the thermal properties
of aggregate and of the cement paste, while mechanical causes are associated mainly with abortion.
5.Impermeability
Penetration of concrete by materials in solution may adversely affect its durability, for instance, when
Ca(OH)2 is being leached out or an attack by aggressive liquids (acids) takes place. Permeability has an
important bearing on the vulnerability of concrete to water and frost. In the case of reinforced cement
concrete, the penetration of moisture and air will result in the corrosion of steel. This leads to an
increase in the volume of the steel, resulting in cracking and spalling of the concrete. Permeability of
concrete is also of importance for liquid retaining and hydraulic structures;
6.Segregation
The tendency of separation of coarse aggregate grains from the concrete mass is called segregation. It
increases when the concrete mixture is lean and too wet. It also increases when rather large and roughtextured aggregate is used. The phenomenon of segregation can be avoided as follows.
i.
ii.
iii.
iv.
Addition of little air-entraining agents in the mix.
Restricting the amount of water to the smallest possible amount.
All the operations like handling, placing and consolidation must be carefully conducted.
Concrete should not be allowed to fall from large heights.
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7.Bleeding
The tendency of water to rise to the surface of freshly laid concrete is known as bleeding. The water
rising to the surface carries with it, particles of sand and cement, which on hardening form a scum layer
is popularly known as laitance. Concrete bleeding can be checked by adopting the following measures.
i.
ii.
iii.
iv.
v.
By adding more cement
By using more finely ground cement
By properly designing the mix and using the minimum quantity of water
By using little air entraining agent
By increasing the finer part of fine aggregate
8.Fatigue
Plain concrete when subjected to flexure, exhibits fatigue. The flexure resisting ability of concrete of a
given quality is indicated by an endurance limit whose value depends upon the number of repetitions
of stress. In concrete pavement design, the allowable flexural working stress is limited to 55% of
the modulus of rupture.
9.Modulus of Elasticity of Concrete
Modulus of elasticity (also known as elastic modulus, the coefficient of elasticity) of a material is a
number which is defined by the ratio of the applied stress to the corresponding strain within the elastic
limit. Physically it indicates a material’s resistance to being deformed when a stress is applied to it.
Modulus of elasticity also indicates the stiffness of a material. Value of elastic modulus is higher for the
stiffer materials.
Modulus of Elasticity, E = f/s
Where:
f = applied stress on the body
s = strain to correspond to the applied stress
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Determination of Modulus of
Elasticity Concrete. Source: http://civilarc.com
Units of Elastic Modulus
Units of elastic modulus are followings:
•
•
In SI unit MPa or N/mm2 or KN/m2.
In FPS unit psi or ksi or psf or ksf.
Modulus of Elasticity of Concrete
Modulus of Elasticity of Concrete can be defined as the slope of the line drawn from stress of zero to a
compressive stress of 0.45f’c. As concrete is a heterogeneous material. The strength of concrete is
dependent on the relative proportion and modulus of elasticity of the aggregate.
To know the accurate value of elastic modulus of a concrete batch, laboratory test can be done. Also,
there are some empirical formulas provided by different code to obtain the elastic modulus of Concrete.
These formulas are based on the relationship between modulus of elasticity and concrete compressive
strength. One can easily obtain an approximate value of modulus of elasticity of concrete using 28 days
concrete strength (f’c) with these formulas.
Elastic Modulus of Concrete from ACI Code
Different codes have prescribed some empirical relations to determine the Modulus of Elasticity of
Concrete. Few of them are given below.
According to ACI 318-08 section 8.5,
Modulus of elasticity for concrete,
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This formula is valid for values of wc between 1440 and 2560 kg/m3.
For normal-weight concrete,
Elastic Modulus of Concrete from BNBC
According to BNBC 2006 section 5.13.2.1,
For stone aggregate concrete,
for normal density concrete
For brick aggregate concrete,
Uses of Concrete
Some utilization of concrete are given below:
1.
2.
3.
4.
5.
6.
7.
8.
It’s an important building product. Concrete is chosen over wood as a construction material.
It is a durable and cost-effective material which is a necessity for underground use.
Concrete is a sustainable choice for residential and commercial projects.
The strength of concrete increases over time.
Concrete can hold up against weather condition and is easy to maintain.
It is budget friendly to use everywhere. It is easy to repair & energy efficient.
Concrete is safe for building occupants.
Concrete is an inert material which doesn’t burn, mildew or feed rot.
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9. Its superior structural integrity provides added degree of protection from the severe weather
as well as an earthquake.
10. Concrete walls and floors make a home quite place of rest, relaxation and rejuvenation.
11. Concrete is produced from locally available materials and leaves a small environmental
footprint while still providing high-level durability.
12. It is used as aggregate in roadbeds or as granular materials while making new concrete.
13. Concrete is fire resistant. It can resist extreme level of flames and heat which is a good choice of
the ceiling in a storage room.
14. Concrete can be shaped in various forms when freshly mixed.
15. Concrete isn’t sensitive to moisture.
16. It doesn’t release any volatile organic compounds into the air which is environment-friendly.
17. Concrete gives a longer service life.
18. It keeps home safe from insects. It doesn’t attract insect pest and rodents. That’s why small
animals cannot burrow through the concrete to make a home.
19. Concrete has multiple design possibilities.
20. Concrete can be used to achieve optimum environmental performance.
21. As it is recyclable, it is possible to use it for addition.
22. High-performance concrete is used to build bridges.
23. Concrete is able to accommodate steel reinforcements in gates, tunnel lines, electrical
controls.
24. A concrete floor can be stamped to create an attractive surface. It can admit natural light
during the day and transmit artificial light after work.
25. Concrete is used in driveways and patios.
Different types of concrete grades and their uses
Grades of concrete are defined by the strength and composition of the concrete, and the minimum
strength the concrete should have following 28 days of initial construction. The grade of concrete is
understood in measurements of MPa, where M stands for mix and the MPa denotes the overall
strength.
Concrete mixes are defined in ascending numbers of 5, starting at 10, and show the compressive
strength of the concrete after 28 days. For instance, C10 has the strength of 10 newtons, C15 has the
strength of 15 newtons, C20 has 20 newtons strength and so on.
Different mixes (M) come in various mix proportions of the various ingredients of cement, sand and
coarse aggregates. For instance, M20 comes in the respective ratio of 1:1:5:3. You can see other
examples below in the table.
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Concrete GradeMix Ratio (cement : sand : aggregates)
Compressive Strength
MPa (N/mm2)Psi
Grades of Concrete
M5
1 : 5 : 10
5 MPa
725 psi
M7.5
1:4:8
7.5 MPa
1087 psi
M10
1:3:6
10 MPa
1450 psi
M15
1:2:4
15 MPa
2175 psi
M20
1 : 1.5 : 3
20 MPa
2900 psi
Standard Grade of Concrete
M25
1:1:2
25 MPa
3625 psi
M30
Design Mix
30 MPa
4350 psi
M35
Design Mix
35 MPa
5075 psi
M40
Design Mix
40 MPa
5800 psi
M45
Design Mix
45 MPa
6525 psi
High Strength Concrete Grades
M50
Design Mix
50 MPa
7250 psi
M55
Design Mix
55 MPa
7975 psi
M60
Design Mix
60 MPa
8700 psi
M65
Design Mix
65 MPa
9425 psi
M70
Design Mix
70 MPa
10150 psi
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Below is a list of a few of the initial concrete grades and what they are best used for.
C10
Used for: Patio slabs, pathways and non-structural work
Type: Domestic & commercial use
C15
Used for: Pavement kerbs and floor blinding
Type: Domestic & Commercial
C20
Used for: Domestic floors and foundations (where the weight of structure will be lighter). Also good
for workshop bases, garages, driveways and internal floor slabs.
Type: Domestic
C25
Used for: Construction in all areas. Multi-purpose concrete mix, usually used for foundations.
Type: Domestic & Commercial
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C30
Used for: Pathways and roadways (this is the lowest grade concrete mix that can be used for this
purpose). More durable than the grades that have come before, and thus is much more weatherresistant and can take heavy road traffic.
Type: Commercial
C35
Used for: Commercial structures. This heavy concrete mix is usually used for creating external walls
and slabs, as well as for structural piling.
Type: Commercial
C40
Used for: Commercial construction sites, creating foundations and beams for structural support and
roads. The most durable in this list, C40 can withstand chemical corrosion also, so is frequently used
on farms where slurry could corrode structures, or in septic tanks.
Type: Commercial
PORTLAND AND HYDRAULICS CEMENT CONCRETE
HYDRAULICS CEMENT:
Hydraulic Cement is a product used to stop water and leaks in concrete and masonry structures.
It is a type of cement, similar to mortar, that sets extremely fast and hardens after it has been mixed
with water. Hydraulic cement is used widely in the construction industry sealing structures below grade
and in situations where structures can be affected or submerged in water.
USES:
•
•
•
•
•
•
•
•
•
•
Swimming Pools
Drainage systems
Foundations
Elevator pits
Basement walls
Manholes
Sealing around concrete and masonry structures
Marine applications.
Chimneys
Cisterns and fountains
PORTLAND CEMENT:
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Portland cement may be defined as a product obtained by finely pulverizing clinker produced by
calcining to incipient fusion, an intimate and properly proportioned mixture of argillaceous and
calcareous materials. Care must be exercised in proportioning the raw materials so that the clinker of
proper constitution may be obtained after burning.
Portland cement is a hydraulic cement capable of setting, hardening and remains stable under
water. It is composed of calcium silicates and some amount of gypsum.
FIGURE: A FLOW DIAGRAM OF PORTLAND CEMENT PRODUCTION
TYPES OF PORTLAND CEMENT:
TYPE
I
IA
II
IIA
II(MH)
II(MH)A
III
IIIA
IV
V
General purpose
Same as Type I, but when air entrainment is desired
For moderate sulfate resistance
Same as type II, but when air entrainment is desired
much like Type II, but when moderate heat of hydration is desired
same as Type II(MH), but when air entrainment is desired
for high early strength
same as Type III, but when air entrainment is desired
for low heat of hydration
for high sulfate resistance
Types IA, IIA and IIIA are cements used to make air-entrained concrete. They have the same
properties as types I, II, and III, except that they have small quantities of air-entrained materials
combined with them.
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Type I: General purpose, for use when the special properties specified for any other types are not
required. It is used as general or normal purpose Portland cement in construction work. It is commonly
used for general construction, especially when making precast, and precast – prestressed concrete that
is not to be in contact with soils or groundwater. Type 1 cement is general use cement in every
construction work unless another cement is specified for construction works
Type II: It is used for constructing structures in which water or soil containing less amount of sulfate.
This type of cement is used where less heat is required during hydration.
Type III: This type of cement is used where high strength is required at a very early period of time. This
type of cement gives a good three-day compressive strength equal to the seven-day compressive
strength of types I and II cement. It is usually used for precast concrete manufacture, where high oneday strength allows a fast turnover of molds. It can also be used in emergency construction and repairs,
and construction of machine bases and gate installations.
Type IV: This type of cement is used where the amount and rate of heat generation must be kept to a
minimum. This type of cement is used where low heat of hydration is required.
Type V: This type is used in concrete to be exposed to alkali soil and groundwater sulfates. It is used as
sulfate resistance Portland cement in construction works.
ADMIXTURES
What is Admixture?
Admixtures are natural or manufactured chemicals which are added to the concrete before or during
mixing. The most often used admixtures are air-entraining agents, water reducers, water-reducing
retarders and accelerators.
Types of Concrete Admixtures
Concrete admixtures are of different types and they are as follows:
1. Accelerating Admixtures
2. Air entraining concrete admixture
3. Pozzolanic Admixtures
4. Damp-proofing Admixtures
5. Gas forming Admixtures
6. Air detraining Admixtures
7. Alkali Aggregate Expansion Inhibiting Admixtures
8. Anti-washout Admixtures
9. Grouting Admixtures
10. Corrosion Inhibiting Admixtures
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11. Bonding Admixtures
12. Fungicidal, Germicidal, Insecticidal Admixtures
13. Coloring Admixtures
1. Water Reducing Admixtures
Water reducing admixtures, the name itself defining that they are used to minimize the water demand
in a concrete mix. Workability is the important property of concrete which is improved with the
addition of water but if water is added more than required the strength and durability properties of
concrete gets affected.
In addition to increase in workability it also improves the strength of concrete, good bond between
concrete and steel, prevents cracking, segregation, honeycombing, bleeding etc.
Water reducing admixtures are also called as plasticizers and these are classified into three types
namely plasticizers, mid-range plasticizers and super plasticizers. Normal plasticizer reduces the
water demand up to 10%, mid-range plasticizers reduce the water demand up to 15% while super
plasticizers reduce the water demand up to 30%.
Calcium, sodium and ammonium lignosulphonates are commonly used plasticizers. Some of the new
generation super plasticizers are acrylic polymer based, poly carboxylate, multicarbovylatethers etc.
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Fig 1: Water Reducing Admixture
2. Retarding Admixtures
Retarding admixtures slow down the rate of hydration of cement in its initial stage and increase the
initial setting time of concrete. These are also called as retarders and used especially in high
temperature zones where concrete will set quickly.
The quick setting in some situations may lead to discontinuities in structure, poor bond between the
surfaces, creates unnecessary voids in concrete etc. Retarders are useful to eliminate this type of
problems.
Commonly used retarding admixture is calcium sulphate or gypsum. Starch, cellulose products,
common sugar, salts of acids are some other retarders. Most of water reducing admixtures are also
acts as retarding admixtures and they are called as retarding plasticizers.
Fig 2: Retarding Admixture (Gypsum)
3. Accelerating Admixtures
Accelerating admixtures are used to reduce the initial setting time of concrete. They speed up the
process of initial stage of hardening of concrete hence they are also called as accelerators. These
accelerators also improves the strength of concrete in it early stage by increasing the rate of
hydration.
Earlier hardening of concrete is useful in several situations such as early removal of formwork, less
period of curing, emergency repair works, for constructions in low temperature regions etc.
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Some of the accelerating admixtures are triethenolamine, calcium formate, silica fume, calcium
chloride, finely divided silica gel etc. Calcium chloride is the cheap and commonly used accelerating
admixture.
Fig 3: Accelerator (Silica Fume)
4. Air Entraining Concrete Admixture
Air entraining admixtures are one of the most important inventions in concrete technology. Their
primary function is to increase the durability of concrete under freezing and thawing conditions.
When added to concrete mix, these admixtures will form millions of non-coalescing air bubbles
throughout the mix and improves the properties of concrete.
Air entrainment in concrete will also improve the workability of concrete, prevents segregation and
bleeding, lower the unit weight and modulus of elasticity of concrete, improves the chemical
resistance of concrete and reduction of cement or sand or water content in concrete etc.
Most used air entrainment admixtures are vinsol resin, darex, Teepol, Cheecol etc. These admixtures
are actually made of Natural wood resins, alkali salts, animal and vegetable fats and oils etc.
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Fig 4: Freezing and Thawing Effect on Concrete
5. Pozzolanic Admixtures
Pozzolanic admixtures are used to prepare dense concrete mix which is bets suitable for water
retaining structures like dams, reservoirs etc. They also reduce the heat of hydration and thermal
shrinkage.
Best pozzolanic materials in optimum quantity gives best results and prevents or reduces many risks
such as alkali aggregate reaction, leaching, sulfate attack etc.
Pozzolanic materials used as admixtures are either natural or artificial. Naturally occurring Pozzolanic
materials are clay, shale, volcanic tuffs, pumicite, etc. and artificial pozzolans available are fly ash,
silica fume, blast furnace slag, rice husk ash, surkhi etc.
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Fig 5: Fly ash
6. Damp-proofing Admixtures
Damp proofing or water proofing admixtures are used to make the concrete structure impermeable
against water and to prevent dampness on concrete surface. In addition to water proof property, they
also acts like accelerators in early stage of concrete hardening.
Damp proofing admixtures are available in liquid form, powder form, paste form etc. The main
constituents of these admixtures are aluminum sulfate, zinc sulfate aluminum chloride, calcium
chloride, silicate of soda etc. which are chemically active pore fillers.
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Fig 6: Dampness on Concrete Surface
7. Gas forming Admixtures
Aluminum powder, activated carbon, hydrogen peroxide are generally used gas forming chemical
admixtures. When gas forming admixtures are added, it reacts with hydroxide obtained by the
hydration of cement and forms minute bubbles of hydrogen gas in the concrete.
The range of formation of bubbles in concrete is depends upon many factors such as amount of
admixture, chemical composition of cement, temperature, fineness etc. The formed bubbles helps the
concrete to counteract the settlement and bleeding problems.
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Fig 7: Activated Carbon Powder
Gas forming admixtures are also used to prepare light weight concrete. For settlement and bleeding
resistance purpose, small quantity of gas forming admixtures which is generally 0.5 to 2% by weight
of cement is used. But for making light weight concrete larger quantity generally 100 grams per bag of
cement is recommended.
8. Air detraining Admixtures
Air-detraining Admixtures are used to remove the excess air from the concrete voids. Sometimes, the
aggregates may release the gas into concrete and air entrained is more than required then this type of
admixtures are useful.
Some of the mostly used air-detraining admixtures are tributyl phosphate, silicones, water insoluble
alcohols etc.
9. Alkali Aggregate Expansion Preventing Admixtures
Alkali aggregate expansion in concrete is happened by the reaction of alkali of cement with the silica
present in the aggregates. It forms a gel like substance and cause volumetric expansion of concrete
which may lead to cracking and disintegration.
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Use of pozzolanic admixtures will prevent the alkali-aggregate reaction and in some cases airentraining admixtures are also useful. Generally used admixtures to reduce the risk of alkali aggregate
reaction are aluminum powder and lithium salts.
Fig 8: Effect of Alkali Aggregate Reaction on Concrete
10. Anti-washout Admixtures
Anti-washout admixtures are used in concrete especially for under water concrete structure. It
protect the concrete mix from being washed out under water pressure. It improves the cohesiveness
of concrete.
This type of admixtures are prepared from natural or synthetic rubbers, cellulose based thickeners
etc.
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Fig 9: Underwater Concreting
11. Grouting Admixtures
Grouting admixtures are added to grout materials to improve the grout properties according to the
requirement of grout. Sometimes, there is a need of quick set grout and sometimes there is a need of
slow set grout to spread into deep cracks or fissures.
Hence, different admixtures are used as grout admixtures based on situation. Accelerators like
calcium chloride, triethanolamine etc. are used as grout admixtures when the grout is to be set
rapidly. Similarly retarders like mucic acid, gypsum etc. are used to slow down the setting time of
grout.
Gas forming admixtures like aluminum powder is added to grout material to counteract the settle of
foundations.
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Fig 10: Grouting
12. Corrosion Preventing Admixtures
Corrosion of steel in reinforced concrete structure is general and it is severe when the structure is
exposed to saline water, industrial fumes, chlorides etc. To prevent or to slow down the process of
corrosion preventing admixtures are used.
Some of the corrosion preventing admixtures used in reinforced concrete are sodium benzoate,
sodium nitrate, sodium nitrite etc.
Fig 11: Corrosion of Steel in Concrete
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13. Bonding Admixtures
Bonding admixtures are used to create a bond between old and fresh concrete surfaces. In general, if
fresh concrete is poured over a hardened concrete surface, there is a chance of failure of fresh
concrete surface due to weak bond with old surface.
To make the bond stronger, bonding admixtures are added to cement or mortar grout which is
applied on the concrete surface just before placing fresh concrete. This type of admixtures are used
for pavement overlays, screed over roof provision, repair works etc.
Bonding admixtures are water emulsions and they are made from natural rubber, synthetic rubbers,
polymers like poly vinyl chloride, polyvinyl acetate etc.
Fig 12: Concrete Pavement Overlay
14. Fungicidal, Germicidal, Insecticidal Admixtures
To prevent the growth of bacteria, germs, fungus on hardened concrete structures, it is recommended
that the mix should have fungicidal, germicidal and insecticidal properties. This properties can be
developed by adding admixtures like polyhalogenated phenols, copper compounds and dieledren
emulsions etc.
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Fig 13: Concrete affected by Fungi
15. Coloring Admixtures
Coloring admixtures are the pigments which produce color in the finished concrete. The admixtures
used to produce color should not affect the concrete strength. Generally coloring admixtures are
added to cement in a ball mill, then colored cement can be obtained which can be used for making
colored concrete. Some of the coloring admixtures and their resultant colors are tabulated below.
Table 1: Coloring Admixtures and their Resultant Colors
Admixture
Color obtained
Iron or Red oxide
Red
Hydroxides of iron
Yellow
Barium manganite and Ultramarine
Blue
Chromium oxide and chromium hydroxide
Green
Ferrous oxide
Purple
Carbon black
Black
Manganese black , Raw umber
Brown
COMPLETED PAVEMENT
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Thickness Determination
Concrete slab thickness plays a critical role in the performance of concrete pavements. A small
deficit in slab thickness can significantly reduce the service life of a concrete pavement. Based on the
structural design procedures for concrete pavements, a reduction in concrete slab thickness by an inch
(2.54 cm) can result in as much as a 50 percent reduction in the service life of the pavement.
Thickness Determination Techniques:
1.Core Boring
For most highway agencies, ASTM C 174 (ASTM 2006a), “Standard Test Method for Measuring
Thickness of Concrete Elements Using Drilled Concrete Cores,” is the standard method to determine the
thickness of as constructed concrete pavement. A process specifically designed to remove a cylinder of
material, much like a hole saw. The material left inside the drill bit is referred to as the core. The
standard core sample diameter for purposes of this test procedure will be 101.6 mm or 152.4 mm.
Generally, the maximum thickness of asphalt concrete pavement to be sampled will be 250 mm. After
the drilling process is done, the height of the cylindrical sample will be measured.
2.Impact-Echo Method
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A non-destructive test available for measuring concrete pavement thickness, such as the ASTM
C 1383, “Standard Test Method for Measuring the P-Wave Speed and the Thickness of Concrete Plates
Using the Impact Echo Method” (ASTM 2006c). One of the most suitable non-destructive test methods
that may be used on concrete for thickness determination or for investigation of possible delamination
in the internal parts of a concrete structure without damaging the surface. This method may be used to
locate internal cracks or large air voids existing in concrete. It is known that impact-echo has been used
successfully on structures with varying geometries and various purposes such as evaluation of concrete
pavements, retaining walls and other reinforced concrete sections. Besides the investigation of the
internal state, it may also be used when the other side of the section cannot be reached, as in the case
of concrete pavements, in order to find the thickness of the section. This is especially important for
quality control and for cost calculations.
3.Magnetic imaging tomography
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It uses MIT-SCAN-T2 device—simple and easy-to-use handheld device that is able to accurately
measure the thickness of pavement layers. The coil mounted in the device generates a pulse of magnetic
field, which induces an eddy current in a pre-placed metal reflector on the surface of the base.
Electromagnetic sensors in the device then measure the intensity of the magnetic field caused by the
eddy current in the reflector.
This technique is medium-independent and can be used to measure concrete thickness of up to
508 mm (20 in.). Using only one hand, the operator uses the device to locate reflectors that have been
pre-placed randomly on the base. The device is then used to measure and record the thickness of the
pavement above the reflector. Each test requires less than a minute to perform.
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STANDARD PAVEMENT THICKNESS AS SET BY DPWH
Portland cement Concrete Pavement (PCCP)
•
For new road construction, rehabilitation or upgrading, the minimum thickness of the pavement
shall be 280 mm. However, a thickness of less than 280 mm.
•
For pavement rehabilitation using the crack and seat method, a minimum thickness of 260 mm.
shall be adopted for the new pavement that will be constructed on top of the deteriorated
concrete pavement.
•
For pavement reblocking, the thickness of the new pavement shall be the same as the replaced
blocks.
Asphalt Pavement
•
For overlaying works, the minimum thickness of the overlay shall be 50 mm.
•
On grounds of economy, pavement thickness of more than 50 mm. shall be considered only if the
cost of the asphalt pavement of such thickness is less than the cost of a 230 mm. thick PCCP.
SIGNIFICANCE OF PAVEMENT THICKNESS DETERMINATION
1. Thickness determination of completed pavement enable engineers to compare the actual
thickness of pavement to the proposed thickness as specified in the construction plan.
2. Pavement thickness was design considering many factors such as traffic and types of vehicles
using the road in a certain area. Thus, information on the actual thickness of the road will
determine its capacity or serviceability.
3. Core boring test are done to ensure that completed pavement followed the standard thickness
prescribed by the Philippine government. This will be the basis whether the road will be open
for use of the public or be removed and reconstructed.
Self-Help: You can also refer to the sources below to help you further understand the
lesson:
Kultermann E. and Spence, William. (2017). Construction Materials, Methods, and
Techniques: Building a sustainable future. 4th Edition. Australia: Cencage Learning
Ahmed, A. and Sturges, J. (2015). Materials science in construction: an introduction.
Abingdon, Oxon; New York, NY: Routledge
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Let’s Check Activity 1. Now that you know some types and properties of common
construction materials let us try to check how far you had learned. In the space provided,
write the term/s being asked in the following statements
_______________1. This test is performed to determine the setting time of hydraulic cement by mean
of manually operated standard.
_______________2. . It is obtained by mixing calcining bauxite and ordinary lime with clinker during the
manufacture of OPC.
_________________ 3. What is the Initial Setting Time and Final Setting Time for Rapid Hardening
Cement?
_________________ 4. It refers to the ease of placement and compaction of a concrete mix.
________________ 5. Concrete grades are denoted by M10, M20, M30, according to their compressive
strength. The “M” denotes _____ design of concrete followed by the compressive strength number in
N/mm2.
________________ 6. A general purpose Portland cement used whenever other special properties are
not necessary. It is used for pavements, sidewalks, reinforced, concrete structural members, bridges,
tanks, water pipes, and masonry building units, among other components.
________________ 7. It tests the ability of unreinforced concrete beam or slab to withstand failure in
bending.
_________________ 8. The compressive strength of normal-weight concrete is between ___ to ___.
_________________ 9. Is a process designed to remove a cylinder of a material, much like a hole saw
for the purpose of evaluating the thickness of a completed pavement.
________________ 10. These admixtures are used to purposely introduce and stabilize microscopic air
bubbles in concrete.
Let’s Analyze
Activity 1. Getting acquainted with the types and properties of some common and
advanced construction materials. what also matters is you should also be able to explain
some its properties. Now, choose 5 most important properties of concrete which you
believe are essential in determining its suitability for intended used in construction.
Why?
Activity 2. Why Normal Consistency test is necessary to be conducted for cement?
In a Nutshell
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Activity 1. The study of types and properties of construction materials is indeed prerequisite to becoming an engineer.
Based on the topics presented and learning exercises that you have done, please feel free to
write advantages of concrete as construction materials. I have indicated what I had learned.
1. Ingredients of concrete are easily available in most of the places.
2. Unlike natural stones, concrete is free from defects and laws.
Now it’s your turn.
3.
4.
5.
Commented [CE2]: Provide are for “In a Nutshell” and
“Q&A”
6.
7.
8.
9.
Q&A List
Do you have any question for clarification?
Questions/Issues
Answers
1.
2.
3.
4.
5.
Keywords Index
cement
icat
concrete
workability
admixture
tensile strength
shear strength
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flexural strength
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STANDARD EXPERIMENTS
Refer to Laboratory Manual
Experiment numbers 12 – 20
Week 6 to 7: Unit Learning Outcomes (ULO 3): At the end of the unit, you are expected to:
a. Demonstrate knowledge and understanding of the properties and behaviors of most common and
advance construction material such as metals and wood.
b. Conduct/Familiarize the methods, procedures and formulas of different experiments on common
construction materials according to international standards such as ASTM & AASTHO.
Big Picture in Focus
ULO 3 a. Demonstrate knowledge and understanding of the properties and behaviors of most
common and advance construction material such as metals and wood.
Metalanguage
This section deals with the study of different types and properties of construction materials such as
metals and wood.
Please proceed immediately to the “Essential Knowledge.
Essential Knowledge
To perform the aforesaid big picture (unit learning outcomes) for the first three (3) weeks of the
course, you need to fully understand the following essential knowledge that will be laid down in the
succeeding pages. Please note that you are not limited to exclusively refer to these resources. Thus, you
are expected to utilize other books, research articles and other resources that are available in the
university’s library e.g. ebrary, search.proquest.com etc.
INTROCTION: METALS & WOODS
WROUGHT IRON, CAST IRON, STEEL AND ALLOYS
Metals are any chemical element having "metallic properties". It is a solid material that is typically
hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity. Metals are
refined from ores that have been extracted from the earth. Metals is one of the four broad categories of
construction materials. Due to the addition of a mixture of materials, metals have a wide variation in
properties.
❖ PROPERTIES OF METALS
◼
Luster: Metals are shiny when cut, scratched, or polished.
◼
Malleability: Metals are strong but malleable, which means that they can be easily bent or
shaped.
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◼
Conductivity: Metals are excellent conductors of electricity and heat. Because they are also
ductile, they are ideal for electrical wiring.
◼
High melting point: Most metals have high melting points and all except mercury are solid at
room temperature.
◼
Sonorous: Metals often make a ringing sound when hit.
◼
Reactivity: Some metals will undergo a chemical change (reaction), by themselves or with
other elements, and release energy. These metals are never found in a pure form, and are
difficult to separate from the minerals they are found in. Other metals don’t react at all with
other metals. This means they can be found in a pure form (examples are gold and platinum).
Because copper is relatively inexpensive and has a low reactivity, it’s useful for making pipes
and wiring.
❖ CLASSIFICATION OF METALS
1. FERROUS METALS
Ferrous metals are those in which the chief ingredient is the chemical element
iron (ferrum). Iron (chemical symbol Fe), mixed with other minerals, is found in
large quantities in the earth’s crust. Iron is a shiny, grayish metal that rusts in damp
air. It is the most abundant of all metals, its pure form rapidly corrodes from
exposure to moist air and high temperatures.To be useful, iron must be extracted
from mined ore, have impurities removed and ingredients added to alter its
properties, and then be formed into usable products.
Ferrous metal products are widely used in the construction industry. They are a major construction
material. For commercial purposes, iron must have alloying elements added to improve its
characteristics.
Annealing is the process of heating iron and allowing it to cool slowly - hardening process.
Pig iron is the starting point for commercial iron products. Iron ore is converted into pig iron in a blast
furnace. It contains 3 to 5 percent carbon and traces of other elements, such as manganese, sulfur,
silicon, and phosphorus.
Blast furnace separates the iron from the waste materials and sinters the ore and flue dust.
Smelting is a process in which the ore is heated, permitting the iron to be separated from impurities
that may be chemically or physically mixed in.
Reduction is a process that separates the iron from oxygen with which it is chemically mixed.
2. WROUGHT IRON
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Wrought iron is the iron containing almost no carbon. It is a mixture of less than 0.3% or ideally
less than 0.1% carbon iron and 1 or 2 percent amount of slag. It is soft, tough, and ductile (easily
worked). It can be heated and reheated and worked into various shapes.
Although wrought iron exhibits properties that are not found in other forms of ferrous metal, it
lacks the carbon content necessary for hardening through heat treatment. Wrought iron may be welded
in the same manner as mild steel, but the presence of oxides or inclusions will provide defective results.
Chemical Composition
Element
Content (%)
Iron, Fe
99-99.8
Carbon, C
0.05-0.25
Phosphorus, P
0.05-0.2
Silicon, Si
0.02-0.2
Sulfur, S
0.02-0.1
Manganese, Mn
0.01-0.1
Physical Properties
Properties
Metric
Imperial
Density
7.7 g/cm3
0.278 lb/in3
Melting point
1540°C
2800°F
Properties
Metric
Imperial
Tensile strength
234-372 MPa
34000-54000 psi
Yield strength
159-221 MPa
23000-32000 psi
Mechanical Properties
Modulus of elasticity 193100 MPa
28000 ksi
Applications of Wrought Iron
•
Decorative items such as railings, outdoor stairs, fences and gates
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•
•
Nuts and bolts
Handrails
3.CAST IRON
gray,
re-
Cast irons have carbon contents above 1.7 percent having white,
and malleable types. Cast iron is obtained from the pig-iron which is
melted with coke and limestone. Cast iron has lot of engineering
properties so, that it can be used in many ways like for sanitary
fittings, rail chairs, casting molds.
Properties of Cast Iron
Good corrosion resistance, so it can be used for water carrying
pipes.
• Does not get attracted to magnet.
•
Specific gravity is 7.5.
Melting point is about 1250oC.
•
Tensile strength is about 150 N/mm2 and compressive strength is about 600 N/mm2.so, it is
good in compression.
•
It becomes soft when placed in salt water and it shrinks on cooling.
•
It cannot be useful for forging work because of lack of plasticity.
•
•
Types of Cast Iron
Grey Cast Iron - as the name suggests, it is grey in color. It has coarse crystalline structure. Its melting
point is very low thus it has weak strength and it is only used for casting purposes.
Malleable Cast Iron - is a type of material that has the ability to form into any shape without breaking
or cracking. It has good corrosive resistance. Its manufacturing process involves two steps. In the first
step, it is casted and cooled as ordinary cast iron and then again it is heated to 1050oC and soaked in
water for long period (several hours or days). Hence, carbon content is slightly reduced and graphite
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content is precipitated as temper carbon. This reduce the brittleness of cast iron. So, it can be worked
easily using machines. It is used for making pipe fittings, fastenings, automobiles etc.
Mottled Cast Iron - is the medium stage cast iron which properties are in between grey cast iron and
white cast iron. It has Small amount of graphite in its composition. So, mottled type fractures are
developed in its micro structure.
Toughened Cast Iron
Toughened cast iron is the combination of cast iron and wrought iron. To obtain this wrought iron scrap
and cast iron melted together. The composition of wrought iron is about 0.15 to 0.25 weight of the cast
iron.
White Cast Iron - is silver in color. Its melting point is high so, strength wise it is better but not used
for delicate casting purposes. Because of its heavy strength, it cannot be used easily.
Ductile Cast Iron- is also called as spheroidal graphite iron. Its
manufacturing process is very easy compared to other types.
Its manufacturing process consists manganese treatment
which helps to increase the carbon content and opposes the
formation of graphite in flaky form. It has very good engineering
properties than malleable cast iron.
Ductile cast iron has very good corrosion resistance, high
strength and durability. So, usage of ductile iron dominates the other types. It is used for making sewer
pipes, water conveying pipes etc.
Chilled Cast Iron- consists two layers of which one layer has white
cast
iron properties and other one has grey cast iron properties. This type
of
iron is used for casting process in which grey cast iron layer is
provided in inner surface and white cast iron layer is provided as outer surface. Hence the casting molds
serve longer. Machine parts are also made using chilled cast iron.
4. STEEL
that
Steel, the world's foremost construction material, is an iron alloy
contains between 0.2% and 2% carbon by weight and sometimes small
amounts of other elements, including manganese.
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Steel specified for structural purposes is of major importance to architects and engineers. It has
low-to-medium carbon content. The American Institute of Steel Construction (AISC) publication Code
of Standard Practice for Steel Buildings and Bridges includes requirements that must be specified in
construction documents, including columns, beams, trusses, bearing plates, and various fastening
devices and connectors. The AISC publication Specification for Structural Steel Buildings details
information on structural steels for use in building construction.
Structural steels fall into four major classifications:
1. Carbon steel (ASTM A36, A529, UNS K02600)
2. Heat-treated construction alloy steel (ASTM A514,
UNS K11630)
3. Heat-treated high-strength carbon steel (ASTM A633, A678, A852, UNS K01803, K01600, K12043)
4. 4. Highstrength
low-alloy
steel (ASTM
A242, A572,
A588 UNS
K11510,
K02303,
K11430)
⚫
Carbon steels must meet maximum content requirements for manganese and silicon. Copper
requirements have minimum and maximum specifications. There are no other minimums specified
for other alloying elements.
⚫
Heat-treated construction alloy steels have more stringent alloying element specifications than
carbon steel. They produce the strongest general-use structural steel.
⚫
Heat-treated high-strength carbon steels are brought to desired strength and toughness levels
by heat-treating. Heat-treating refers to the process of heating and cooling metals to produce
changes in the physical and mechanical properties.
⚫
High-strength low-alloy steels are a group of steels to which alloying elements have been added
to produce improved mechanical properties and greater resistance to atmospheric corrosion. Their
carbon range is typically from 0.12 to 0.22 percent.
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Commercial steels are also generally classified into four groups that differ according to their metal
alloy content and end-use applications:
1. Carbon steels include low carbon (less than 0.3% carbon), medium carbon (as much as 0.6%
carbon), high carbon (as much as 1% carbon), and ultra-high-carbon (as much as 2% carbon) steels.
Low carbon steel is the most common and the weakest of the three types. It's available in a wide
array of shapes, including sheets and beams. The higher the carbon content, the more difficult the
steel is to work with.
•
High carbon and ultra-high-carbon steels are used in cutting tools, radiators, punches, and
wires.
•
2. Alloy steels contain other metals such as aluminum, copper, or nickel. They may be used in auto
parts, pipelines, and motors.
3. Stainless steels always contain chromium and maybe also nickel or molybdenum. They are shiny
and generally resistant to corrosion.
Types of stainless steel
✓ Ferritic- which is similar to carbon steel and strongly resistant to stress corrosion cracking but is
not good for welding.
✓ Austenitic- which is the most common and
good for welding
✓ Martensitic- which is moderately resistant to
corrosion but high in strength.
✓ Duplex- which consists of half ferritic and half
austenitic steels and is stronger than either of those
two types. Because stainless steels are easily
sterilized, they are often used in medical equipment
and instruments and food production equipment.
4. Tool steels are alloyed with hard metals such as
vanadium, cobalt, molybdenum, and tungsten. As
their name suggests, they are often used to make
tools, including hammers.
Structural Steel Shapes
⚫
W-shape (wide flange) / W 16 3 31 indicates a W-shape with a web 16 inches deep and a weight
of 31 pounds per linear foot. The W-shape has parallel inner and outer flange surfaces with a
consistent thickness. The most widely used structural steel member is the W-shape, whose crosssection forms the letter H. It is designed so that its flanges provide strength in a horizontal plane,
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while the web gives strength in a vertical plane. W-shapes are used as beams, columns, truss
members, and in other load-bearing applications.
⚫
S-shape (American Standard I-beam) has a slope of approximately 17 degrees on the inner flange
surfaces. It is distinguished by its cross-section being shaped like the letter I. S-shapes are used less
frequently than are W-shapes, since the S-shapes provide less strength.
⚫
C-shape (American Standard channel) is similar to the S-shape in that its inner flange surface is
also sloped. It is called the American Standard channel and has a cross-section similar to the letter
C. It is especially useful in locations where a single flat face without a flange on one side is required.
The C-shape is not very efficient for a beam or column when used alone, but can be efficiently built
up of channels welded together with other structural shapes.
⚫
The bearing pile, or HP-shape, is almost identical to the W-shape except that the flange thickness
and web thickness of the bearing pile are equal, whereas the W-shape has different web and flange
thicknesses.
⚫
Steel angle is a structural shape whose cross-section resembles the letter L. Angles are available in
an equal leg angle and an unequal leg angle. The angle is identified by the length and thickness of
its legs; for example, 8 in. 3 6 in. 3 1/2 in. When an angle has unequal legs, the dimension of the
wider leg is given first. The third dimension applies to the thickness of the legs, which always have
equal thickness.
⚫
Structural tees have a cross-section that resembles the letter T. They are produced by splitting the
webs of beams with rotary shears. Structural tees are designated by their depth and weight per
liner foot.
⚫
Steel pipe and structural tubing are available in square, rectangular, and circular shapes and are
commonly used for columns and other load-bearing applications. They are designated by their
cross-sectional dimensions.
⚫
Steel plate is a structural shape whose cross-section is in the form of a flat rectangle that has a
width of greater than 8 in. and a thickness of 1/4 in. or greater. Plates frequently are referred to by
their thickness and width in inches, as plate 1/2 in. 3 24 in. Plates are frequently used to make
connections between other structural members or as component parts of built-up structural
members.
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NONFERROUS METALS
Nonferrous metals are those containing little or no iron. In other words, all metals other
than iron and steel are nonferrous. Nonferrous metals commonly found in construction include
aluminum, copper, lead, tin, and zinc.
1. ALUMINUM
Aluminum (chemical symbol Al) is a versatile material used widely in
building, and the construction industry is one of its largest consumers.
Aluminum is lightweight, having a specific gravity of only 2.7 times that
of water and approximately one-third that of steel. For many products,
aluminum must have alloying elements added to alter its physical
properties. The major alloying elements added to aluminum are
manganese, copper, magnesium, silicon, and zinc.
Properties:
⚫
Pure aluminum melts at 1,220°F (665°C), considerably lower than the melting point of other
structural metals. It also is relatively weak as far as mechanical properties are concerned.
⚫
Aluminum elastically deforms about three times more than steel under comparable loading.
⚫
It can be strengthened by alloying, cold working, or strain hardening.
⚫
Aluminum alloys do not lose ductility or become brittle at cryogenic (low) temperatures.
⚫
Aluminum is a good conductor of electricity. Compared to copper wire of the same diameter,
aluminum’s conductivity is roughly 65 percent that of copper.
⚫
Aluminum Alloys is relatively soft and ductile and has a tensile strength of around 7,000 psi
(48,258 kPa).
Aluminum alloys classifications:
1. Wrought alloys are those that are mechanically worked by processes, such as forging, drawing,
extruding, or rolling, to form sheet material.
2. Cast alloys are those used to produce a product for which the molten metal is cast in a finished shape,
such as a grille, in a sand mold or permanent mold.
2.COPPER
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Copper (chemical symbol Cu) is a nonmagnetic
reddishbrown metal with excellent electrical and
thermal conductivity.
Properties:
⚫
Copper has the highest conductivity properties of all commonly used metals except silver.
⚫
It is ductile, malleable, and easily worked.
⚫
When alloyed, it offers a wide range of properties suitable for a variety of construction applications.
⚫
High resistance to corrosion, wear defiance makes it ideal for plumbing pipe, gas lines, and
components exposed to the atmosphere or corrosive chemical elements.
⚫
Its ductility properties make it a material easily bent, stretched, stamped, machined, and otherwise
formed into useful products.
⚫
Copper has a relatively low tensile strength, about 32,000 psi, which can be improved by heattreating, cold-working, and alloying.
⚫
Copper has a melting point of 1,981°F (1,083°C) and a coefficient of thermal expansion of
0.0000168/°F (0.0000093/°C).
Uses of Copper and Copper Alloys
⚫
Copper are excellent for outdoor uses, such as siding, roofing, flashing, guttering, and screen
wire.
⚫
Copper Alloys are used extensively for plumbing pipe in residential and commercial structures and
in the manufacture of plumbing fittings, such as valves, drains, and faucets.
⚫
Sewage treatment plants and industrial plants, such as chemical processing installations, utilize
copper for many purposes, including lining vessels that contain corrosive materials.
⚫
Various types of hardware and fasteners, such as nails, screws, and bolts, are made from copper
alloys.
3.LEAD
Lead (chemical symbol Pb) is a soft, heavy metal with
good corrosion resistance that is easily worked. Its
ability to resist penetration from radiation is a unique
feature.
Properties of Lead
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⚫
Lead has high density and weight.
⚫
Lead is usually soft and malleable.
⚫
Lead has low melting point (620°F; 327°C)
⚫
Lead has a good electrical conductivity.
⚫
Lead has low strength and lack of elasticity.
Uses of Lead
Lead pipes and tank liners are used in installations that process highly corrosive materials, but
they are never used for piping to carry drinking water.
•
•
Lead is a good self-lubricant, it is used when high-pressure lubricating is necessary.
Lead solder works for electrical connections because it is a good conductor, but it is not used on
water pipe connections.
•
Lead pipe and lead-lined tanks have high corrosion resistance and can find use in industrial
production applications, such as in the chemical manufacturing industry.
•
Sheet lead is used for roofing, flashing, and spandrels in areas where there is severe industrial
air contamination or on seacoasts.
•
4.ZINC
Zinc (chemical symbol Zn) is a bluish-white metal that is brittle and has low strength. It is often
referred to as a white metal and is widely used as a protective coating over steel to prevent corrosion.
Properties
⚫
Zinc has low strength and is brittle.
⚫
Zinc has a low melting point of 787°F (419°C).
⚫
It is also subject to creep, a permanent dimensional
deformation over time.
⚫
Its tensile strength can be greatly increased by cold-working and alloying.
⚫
It can be hot and cold rolled, drawn, extruded, cast, and machined.
⚫
It can be joined by welding, soldering, and various mechanical fasteners.
Uses of Zinc
•
Zinc as the main agent for galvanizing - forming a protective coating over steel to prevent rust.
Zinc are used for some types of hardware and plumbing items. They are usually die cast and
finished by polishing or plating with chromium, brass, or other materials.
•
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•
Zinc also finds use as an alloying element in brasses.
Various zinc compounds serve in the production of paper, plastics, ceramics, rubber, abrasives,
paint, and other products.
•
Zinc is also used for specialized products in which corrosion resistance is important, such as
anchors, flashing, screws, nails, expansion joints, and corner beads.
•
Solid zinc strip material is used to produce a wide range of products, such as low-voltage buss
bars, cavity wall ties, electric cable binders, electric motor covers, grading screens, and roofing and
fascia material.
•
QUALITY TEST FOR BENDING, TENSION AND CHEMICAL ANALYSIS
Terminology
Stress
Stress is the ratio of applied force F to a cross section area - defined as "force per unit area".
•
•
•
Tensile stress - stress that tends to stretch or lengthen the material - acts normal to the
stressed area
Compressive stress - stress that tends to compress or shorten the material - acts normal to the
stressed area
Shearing stress - stress that tends to shear the material - acts in plane to the stressed area at
right-angles to compressive or tensile stress
Strain (Deformation)
Strain is defined as "deformation of a solid due to stress".
•
•
Normal strain - elongation or contraction of a line segment
Shear strain - change in angle between two line segments originally perpendicular
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Hooke's Law
Most metals deform proportional to imposed load over a range of loads. Stress is proportional
to load and strain is proportional to deformation as expressed with Hooke's Law.
Bending Strength / Flexural Strength
-Is defined as its ability to resist deformation under load.
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Tensile Strength
- is the ability to undergo a great deal of force without breaking or deforming. This is due to a
mixture of strength and flexibility.
“Standard Test Methods for Tension Testing of Metallic Materials”
REFERENCED STANDARD: ASTM E8/ E8M – 13a
Suppose that a metal specimen be placed in tension-compression-testing machine. As the axial
load is gradually increased in increments, the total elongation over the gauge length is measured at each
increment of the load and this is continued until failure of the specimen takes p3lace. Knowing the
original cross-sectional area and length of the specimen, the normal stress σ and the strain ε can be
obtained. The graph of these quantities with the stress σ along the y-axis and the strain ε along the xaxis is called the stress-strain diagram. The stress-strain diagram differs in form for various materials.
The diagram shown below is that for a medium-carbon structural steel.
Metallic engineering materials are classified as either ductile or ductile materials. A ductile
material is one having relatively large tensile strains up to the point of rupture like structural steel and
aluminum, whereas brittle materials has a relatively small strain up to the point of rupture like cast iron
and concrete. An arbitrary strain of 0.05 mm/mm is frequently taken as the dividing line between these
two classes.
ASTM E8 describes tensile testing of metals such as steel or metal alloys. These test methods
cover the tension testing of metallic materials in any form at room temperature, specifically, the
methods of determination of yield strength, yield point elongation, tensile strength, elongation, and
reduction of area, modulus of elasticity and, rupture strength.
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Proportional Limit (Hooke's Law)
From the origin O to the point P called proportional limit, the stress-strain curve is a straight
line. This linear relation between elongation and the axial force causing was first noticed by Sir Robert
Hooke in 1678 and is called Hooke's Law that within the proportional limit, the stress is directly
proportional to strain.
Elastic Limit
The elastic limit is the limit beyond which the material will no longer go back to its original shape
when the load is removed, or it is the maximum stress that may developed such that there is no
permanent or residual deformation when the load is entirely removed.
Elastic and Plastic Ranges
The region in stress-strain diagram from O to P is called the elastic range. The region from P to
R is called the plastic range.
Yield Point
Yield point is the point at which the material will have an appreciable elongation or yielding
without any increase in load.
Ultimate Strength
The maximum ordinate in the stress-strain diagram is the ultimate strength or tensile strength.
Rapture Strength
Rapture strength is the strength of the material at rupture. This is also known as the breaking
strength.
Significance and Use:
Tension tests provide information on the strength and ductility of materials under uniaxial
tensile stresses. This information may be useful in comparisons of materials, alloy development,
quality control, and design under certain circumstances.
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Apparatus:
•
•
•
•
Universal (Hydraulic) Testing Machine is capable of applying tensile load at a controlled rate of
deformation or load.
A gripping device, used to transmit the load from the testing machine to the test.
An extensometer, used to measure the deformation of the specimen.
Caliper used to measure the dimensions of the specimen.
Test Procedure:
1. Measure and record the specimen dimensions necessary to determine the cross sectional area at its
smallest point. The original cross sectional area is used for all engineering stress calculations.
2. Use ink and a scribe or punch to place gauge marks on the test specimen at the appropriate gauge
length. The distance between the gaue marks after the specimen is broken is used to determine the
percent elongation at break. Note: To accurately compare elongation values between tests, the gauge
lengths must be the same.
3. Zero the testing machine without the specimen inserted in the grips. Then install the specimen in the
grips and start loading the sample. The speed of testing is generally specified in one of three
manners: a) the rate of straining of the specimen (0.5 in/in of the gauge length per minute ;) b) the
rate of stressing of the specimen; or c) the rate of separation of the crossheads. In addition, the test
rate is to remain constant through yield but can then be increased when determining ultimate tensile
strength and elongation at break.
4. Run the test until specimen failure or fracture. Remove the broken sample from the machine and fit
the fractured ends together. Measure the distance between the gage marks to the nearest 0.05
millimeters.\
Analysis and Results:
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•
•
•
Plot the stress versus strain curve.
Determining the yield strength using offset method
Determining the modulus of elasticity using Hooke’s law.
σ=Eε
where:
E = Modulus of elasticity
σ = stress in proportional limit
ε = corresponding strain, mm/mm (in/in)
•
Calculate the tensile strength
where:
σ = tensile strength/ ultimate strength, in MPa (psi)
Pmax = maximum load carried by the specimen during tension test, N (lb)\
A = original cross- sectional area of the specimen, mm² (in².)
•
Calculate the elongation
Percent elongation = [ (Ls-Lo)/Lo) x 100]
Where:
Ls= gauge length after rupture, mm (in.)
Lo= original gauge length, mm (in.)
For elongation > 3.0%, fit the ends of the fractured specimen together and measure Ls as the
distance between two gauge marks. For elongation ≤ 3.0%, fit the fractured ends together and apply an
end load along the axis of the specimen sufficient to close the fractured ends together, then measure Ls
as the distance between gauge marks.
•
Calculate the rupture strength
Where:
= rupture strength, MPa (psi)
Pf = final load, N (lb)
A = original cross- sectional area of the specimen, mm² (in².)
•
Calculate the reduction of cross-sectional area
Percent reduction in cross- sectional area = [ (Ao – As)/Ao ) x 100 ]
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Where:
Ao = original cross- sectional area of the specimen, mm² (in².)
As = cross-sectional area after rupture, mm² (in².)
Replacement of the Specimen:
The test specimen should be replace if
▪
▪
▪
▪
the original specimen had wrong dimensions
the test procedure was incorrect
the fracture was outside the gauge length
for elongation determination, the fracture was outside the middle half of the gauge length.
Example:
The following data were obtained during a tension test of an aluminum alloy. The initial diameter of
the test specimen was 0.505 in. and the gage length was 2.0 in.
Load (lb)
Elongation (in.)
Load (lb)
Elongation (in.)
0
0
14 000
0.020
2 310
0.00220
14 400
0.025
4 640
0.00440
14 500
0.060
6 950
0.00660
14 600
0.080
9 290
0.00880
14 800
0.100
11 600
0.0110
14 600
0.120
12 600
0.0150
13 600
Fracture
Plot the stress-strain diagram and determine the following mechanical properties: (a) proportional
limit; (b) modulus of elasticity; (c) yield point; (d) yield strength at 0.2% offset; (e) ultimate strength;
and (f) rupture strength.
Area, A = 0.25π(0.5052) = 0.0638π in2
Length, L = 2 in
Strain = Elongation/Length
Stress = Load/Area
Load (lb)
Elongation (in.)
Strain (in/in)
Stress (psi)
0
0
0
0
2 310
0.0022
0.0011
11 532.92
4 640
0.0044
0.0022
23 165.70
6 950
0.0066
0.0033
34 698.62
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9 290
0.0088
0.0044
46 381.32
11 600
0.011
0.0055
57 914.24
12 600
0.015
0.0075
62 906.85
14 000
0.02
0.01
69 896.49
14 400
0.025
0.0125
71 893.54
14 500
0.06
0.03
72 392.80
14 600
0.08
0.04
72 892.06
14 800
0.1
0.05
73 890.58
14 600
0.12
0.06
72 892.06
13 600
Fracture
67 899.45
From stress-strain diagram:
a.
b.
c.
d.
Proportional Limit = 57,914.24 psi
Modulus of Elasticity:
E = 57914.24/0.0055 = 10,529,861.82 psi
E = 10,529.86 ksi
Yield Point = 69,896.49 psi
Yield Strength at 0.2% Offset:
Strain of Elastic Limit = ε at PL + 0.002
Strain of Elastic Limit = 0.0055 + 0.002
Strain of Elastic Limit = 0.0075 in/in
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The offset line will pass through Q (See figure below):
Slope of 0.2% offset = E = 10,529,861.82 psi
Test for location:
slope = rise / run
10,529,861.82 = (6989.64 + 4992.61) / run
run = 0.00113793
Slope of EL to YP
σ1 / ε1 = 6989.64/0.0025
σ1 / ε1 = 2 795 856
ε1 = σ1 / 2 795 856
For the required point:
E = (4992.61 + σ1) / ε1
10 529 861.82 = (4992.61 + σ1) / (σ1 / 2 795 856)
3.7662 σ1 = 4992.61 + σ1
σ1 = 1804.84 psi
Yield Strength at 0.2% Offset
= EL + σ1
= 62906.85 + 1804.84
= 64 711.69 psi
e.
Ultimate Strength = 73 890.58 psi
f. Rupture Strength = 67 899.45 psi
“Standard Test Methods for Bend Testing of Material for Ductility”
“Guided Bend”
REFERENCED STANDARD: ASTM E290-14
Forces and couples acting on the materials (metals) cause bending (flexural stresses) and
shearing stresses on any cross section of the materials (metals) and deflection perpendicular to the
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longitudinal axis of the materials (metals). Bend test machines are typically universal testing
machines specifically configured to evaluate material ductility, bend strength, fracture strength, and
resistance to fracture.
These test methods cover bend testing for ductility of materials were a guided-bend test using
a mandrel or plunger of defined dimensions to force the mid-length of the specimen between two
supports separated by a defined space.
After bending, the convex surface of the bend is examined for evidence of a crack or surface
irregularities. If the specimen fractures, the material has failed the test. When complete fracture does
not occur, the criterion for failure is the number and size of cracks or surface irregularities visible to the
unaided eye occurring on the convex surface of the specimen after bending, as specified by the product
standard. Any cracks within one thickness of the edge of the specimen are not considered a bend test
failure. Cracks occurring in the corners of the bent portion shall not be considered significant unless
they exceed the size specified for corner cracks in the product standard.
Significance and Use:
Bend tests for ductility provide a simple way to evaluate the quality of materials by their ability
to resist cracking or other surface irregularities during one continuous bend. No reversal of the bend
force shall be employed when conducting these tests.
Apparatus:
300 Series Electromechanical Universal Test Machines
Force range of 5 kN to 600 kN (1,125 lbf to 135,000 lbf)
The most popular choice for static tension and compression tests,
these dual column testers are available in both tabletop and floor
standing models
600 Series Universal Test Machines
Force range of 300 kN to 2,000 kN (67,500 lbf to 450,000 lbf)
The best choice for performing static tension and/or
compression applications when force capacities of 300 kN
(67,000 lbf) or more are needed
Includes its own grips
ASTM E290 Guided Bend Weld Test Fixture
are used to convert the axial motion or rotary motion of
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the ELF and Instron
testers into various forms of bending
motion or motions that combine bending and other motion
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PLUNGER OR MANDREL
A plunger forces the specimen into a 180° bend against
rollers on a base
Test Procedure:
1. Place the specimen over two rounded supports separated by a clearance (C) equal to (2r + 3t), 6
(t/2), where (r) is the radius of the plunger or mandrel and (t) is the specimen thickness.
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2. Bend the specimen by applying a force through a plunger or mandrel in contact with the
specimen at the mid-length between supports (C/2) on the opposite side of the specimen from
the end supports. Apply the bending force smoothly and without shock.
3. Continue bending until failure occurs, or until the specified angle of bend, or maximum angle for
the fixture is achieved. The angle of bend is measured while the specimen is under the bending
force.
4. When the required angle cannot be achieved in the bend fixture shown in Fig. 3, complete the
test by pressing the specimen between suitable platens until the specified conditions of bend are
obtained. Apply the force smoothly, without shock. When it is desired not to exceed 180° of bend
while completing the bend, place between the two legs of the specimen a spacer having a
thickness twice the required bend radius,
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Calculation:
•
Compute for Bending Strength
Flexure Formula:
OR
Where:
fb = bending stress
Mmaxx = the largest bending moment of the specimen
C = is the distance the neutral axis to the outermost point of the section
E = modulus of elasticity of the specimen
R = Radius of Curvature a point to the neutral axis
Example:
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“Standard Test Methods for Standard Test Methods for Chemical Analysis of Carbon Steel, LowAlloy Steel, Silicon Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel,
Ingot Iron, and Wrought Iron”
REFERENCED STANDARD: ASTM E350- 95
This test method covers the chemical analysis of carbon steels, low-alloy steels, silicon electrical
steels, ingot carbon steels, low-alloy steels, silicon electrical steels, ingot iron, and wrought iron having
chemical compositions within iron, and wrought iron having chemical compositions within the
following limits:
Element
Concentration Range, %
Aluminum
0.001 to 1.50
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Antimony
0.002 to 0.03
Arsenic
0.0005 to 0.10
Bismuth
0.005 to 0.50
Boron
0.0005 to 0.02
Calcium
0.0005 to 0.01
Cerium
0.005 to 0.50
Chromium
0.005 to 3.99
Cobalt
0.01 to 0.30
Columbium (Niobium)
0.002 to 0.20
Copper
0.005 to 1.50
Lanthanum
0.001 to 0.50
Manganese
0.01 to 2.50
Molybdenum
0.002 to 1.50
Nickel
0.005 to 5.00
Nitrogen
0.0005 to 0.04
Oxygen
0.0001 to 0.03
Phosphorus
0.001 to 0.25
Selenium
0.001 to 0.50
Silicon
0.001 to 5.00
Sulfur
0.001 to 0.60
Tin
0.002 to 0.10
Titanium
0.002 to 0.20
Tungsten
0.005 to 0.10
Vanadium
0.005 to 0.50
Zirconium
0.005 to 0.15
Some of the concentration ranges are too broad to be covered by a single test method and
therefore this broad to be covered by a single test method and therefore this standard contains multiple
test methods for some elements. The user must select the proper test method by matching the
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information given in the Scope and Interference sections of each test method with the composition of
the alloy to be each test method with the composition of the alloy to be analyzed.
Significance and Use:
•
These test methods for the chemical analysis of metals and alloys are primarily intended as
referee methods to test such materials for compliance with compositional specifications,
particularly those under the jurisdiction of ASTM Committees A-1 on Steel, Stainless Steel, and
Related Alloys and A-4 on Iron Castings. It is assumed that all who use these test methods will
be trained analysts capable of performing common laboratory procedures skillfully and safely.
It is expected that work will be performed in a properly equipped laboratory und under
appropriate quality control practices.
REINFORCING STEEL
Most people are familiar with reinforcing steel, commonly called "rebar". It is used in bridges,
buildings, skyscrapers, homes, warehouses, and foundations to increase the strength of a concrete
structure.
Rebar is used in concrete to provide additional strength, as concrete is weak in tension, while
steel is strong in both tension and compression. Steel and concrete have similar coefficients of thermal
expansion, so a concrete structural member reinforced with steel will experience minimal stress as the
temperature changes.
Types of Steel Reinforcement
The steel reinforcement used in concrete construction is mainly of 4 types.
1. Hot Rolled Deformed Bars
Hot rolled deformed bars are most commonly used steel reinforcement for R.C.C structures. As the name
says, the hot rolling of the reinforcement is undergone leaving certain deformations on its surface in
the form of ribs. These ribs help to form a bond with the concrete. The typical yield strength of hotrolled deformed bars is 60000psi.
2. Cold Worked Steel Bars
A cold worked reinforcement bar is obtained by letting the hot
rolled steel bars to undergo cold working. In the cold working process,
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the bars will undergo twisting and drawing. The process is performed at room temperature. The
cold worked steel bars do not undergo a plastic yield thus have less ductility when compared with
hot rolled bars.
3. Mild Steel Plain Bars
The mild steel plain reinforcement bars do not have ribs on their surface. They have a plain
surface. These bars are used for small projects where the major concern is the economy. The tensile
yield strength of these bars has a value of 40000psi.
4. Prestressing Steel Bars
The prestressing steel reinforcement are steel bars used in the form of strands or
tendons. Multiple strands are employed in concrete in order to perform the prestressing action.
The strands are made of multiple wires either 2 or 3 or 7 wire strands. The wires used here are
cold formed and have a high tensile strength ranging from 250000 – 270000 psi. This high
strength helps to effectively prestress the concrete.
Need for Steel Reinforcement
Plain concrete is weak in tension and strong in compression. Tensile property for concrete
structures is obtained by incorporating steel reinforcement. The steel reinforcement is strong in both
tension and compression. The tensile property provided by the steel reinforcement will prevent and
minimize concrete cracks under tension loads.
The coefficient of thermal expansion of steel reinforcement and concrete are similar in that they
undergo similar expansions during temperature changes. This property will ensure that the concrete is
subjected to minimal stress during temperature variations. The surface of the steel reinforcement bars
is patterned to have a proper bond with the surrounding concrete material.
The two main factors that provide strength to the concrete structures are steel and concrete. The
design engineer will combine both the elements and design the structural element such a way that the
steel resists the induced tensile and shear force, while the concrete takes up the compressive forces.
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Advantages of Steel Reinforcement
Steel reinforcement is a reinforcing choice compared to other reinforcing materials due to its
unique advantages. They are:
•
•
•
•
•
Compatibility with Concrete: The fresh concrete is placed on the formwork mold already
prepared with reinforcement. The steel reinforcement won’t float in concrete during the
concrete placing procedure. Hence, steel reinforcement does not demand special tying up with
formworks.
Robustness of Steel Reinforcement: The steel bars are robust in nature that they have the ability
to withstand the rigors, the wear and tear during the construction activities.
Bent Property of Steel Reinforcement: The steel bars once manufactured to standard size, it can
be bent to the required specifications. Hence fabricated steel bars are delivered easily at the site.
Recycling Property: The steel reinforced left over after the service life of a structure is recycled
again and used for new construction.
Easily Available: Every region of a country will have a steel supplier or manufacturer. Hence steel
reinforcement is easily available.
Disadvantages of Steel Reinforcement
The main disadvantages of steel reinforcement are mentioned below:
•
•
•
Reactive Nature of Steel Reinforcement: In concrete structures where the cover is small and
subjected to external moisture and salt action, the reinforcement undergoes reaction and starts
to corrode. These can lessen the strength of concrete and finally to failure.
Expensive: The cost of steel reinforcement in high. This will increase the cost of construction
Melts at high temperature: At higher temperatures, the steel reinforcement may melt. This is the
reason why the steel reinforcement are tied up and not welded.
If reinforcing bars have been sitting on the jobsite for a while, and begin to show signs of rust,
can they still be used that way?
The answer is "yes," but with certain exceptions. There are a number of things that can get onto
the surface of rebar and affect the bond strength — the bond between the reinforcing bar and the
concrete. These include scale, rust, oil, and mud.
Scale is a material found normally on the bars that is produced at the time the bars are
manufactured. It results from the cooling of the hot metal. Loose scale is usually removed when the bars
are handled at the fabricating shop — or it falls off while it's being loaded, unloaded, or handled.
Rust actually improves bond because it increases the roughness of the surface. However — and
this is the exception — if there is so much rust that the weight of the bar is reduced OR the height of the
deformations is reduced to below that weight, area, or deformation required by the applicable ASTM,
then the rust is considered harmful.
If oil and grease gets onto the surface of the bar, it must be cleaned off. You can do this by wiping
it off with a solvent. And finally, mud. You should load and unload bars to avoid getting them covered
with mud. Any mud on the bars needs to be washed off before using the bars.
STEEL BARS
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Steel reinforcing bars, also called as “rebars”, are used as a tension device for concrete
construction. It strengthens and aids the concrete under tension, since concrete is known to be strong
under compression, yet weak in its tensile strength.
Rebars are very essential for ensuring safe, durable structures that will be reliable for years.
Having no reinforced steel to aid, the natural expansion and contraction of the concrete will cause weak
areas to develop, which will ultimately collapse in the long run.
Rebars are hot-rolled in much same way as structural shapes. It has a round cross-sectional area.
It usually have deformations with ribs, lugs or indentations for better bonding with concrete, reduce
risk of slippage, and also for the increase of the tensile strength of a structure.
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PRODUCTION OF REBARS
1. Steel (carbon or alloy) is melted down to liquid form, which requires an extreme amount of heat
to achieve. Once melted, the liquid steel is pulled through small round openings to give the rebar
its shape.
2. While unfinished steel is the cheapest form of rebar available, some jobs necessitate epoxycoated or stainless steel. The reason being is that rust can occur when the rebar has prolonged
exposure to salt water, which can ultimately lead to a build-up of internal pressure that can cause
the concrete form to crack. Since this is not a profitable or safe option in the long-term, most
developers will opt to purchase higher-grade material.
3. Once the steel has been properly shaped, the manufacturer will make the twists and grooves on
the metal to ensure it will stay firmly in place inside the structure.
4. Since these reinforced metal bars are highly hazardous when it comes to installation, their ends
are often covered with plastic caps to prevent accidental harm to construction workers.
5. Rebar is often distributed straight from the manufacturer to the job site, although contractors
can arrange for pickup if they need to. Once on site, the product will need to be bent to the proper
specs. This is accomplished with specialty hydraulic benders and cutters. Only certain types of
rebar can be welded, which is why many construction companies utilize wire and coupling
splices to join the ends together.
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I.
BAR MARKINGS
There are many ways to identify reinforcing steel bar (rebar) from the production mill to the
fabrication shop to the jobsite. Some rebars have the same appearance that leads to some people finding
it hard to identify the rebar themselves, which may cause mistakes easily.
Engineers should have the knowledge about the manufacturing and composition of each bar of
reinforcing steel.
ASTM Rebar Markings:
❖
Each individual reinforcing bar is manufactured with a series of individual markings:
▪
The first letter or symbol identifies the producing mill and its deformation pattern.
▪
The next marking is the bar size. It is about the bars' diameter and length.
▪
The third marking symbol designates the type of reinforcing steel ,usually either ;
• "S" for carbon-steel (ASTM A615)
• "W" for low-alloy steel (ASTM A706)
• "SS" for stainless steel (ASTM A955)
• "R" for rail-steel (ASTM A996)
• "I" for axle-steel (ASTM A996)
• "A" for rail-steel (ASTM A996)
• "CS" for low-carbon chromium (ASTM A1035)
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▪ The last marking shows the grade of reinforcing bar ;
• 40: grade 40
• 60: grade 60
• 75: grade 75
• 4: grade 420, also grade 60
• 5: grade 520, also grade 75
Furthermore, the grade also can be identified by its additional lines, which must be at least five
deformations long. If it has no line, it means grade 40. If there is an addition of one line it represents
grade 60, or two lines grade 75, three lines grades 80 and 100, and four lines grade 120.
II.
BASIC PROPERTIES OF REINFORCED STEEL
Rebar, also known as reinforcement steel and reinforcing steel, is a steel bar or mesh of steel
wires used in reinforced concrete and masonry structures to strengthen and hold the concrete in
tension. To improve the quality of the bond with the concrete, the surface of rebar is often patterned.
❖ Different uses of rebar include:
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▪
Primary reinforcement
▪
Secondary reinforcement
▪
Provide resistance to concentrated loads, spreading it through a wider area.
▪
Assist other steel bars in accommodating their loads by holding them in the correct position.
❖ The Properties of Reinforcing Steel are:
1. Strength
The steel is strong as a material, due to uniform lattice structure at the atomic level.
2. Ductility
The ability of steel to be drawn into wires is quantitatively higher than other metals.
3. Malleability
The steel can readily be beaten into sheets due to the intrinsic property of the alloy due to its
lattice structure.
4. Weldability
Steel materials can easily be welded, as their melting temperature is within the limit of majority
welders.
5. Durability
Steel products survive years of damage, wear and tear, and endure impacts before failures are
observed.
6. Toughness
Steel as a material tough, making it resistant to sudden impact.
The rougher the surface of the steel, the better it adheres to concrete. Thus steel with a light, firm
layer of rust is superior to clean steel; however, steel with loose or scaly rust is inferior. Loose or scaly
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rust can be removed from the steel by rubbing the steel with burlap or similar material. This action
leaves only the firm layer of rust on the steel to adhere to the concrete.
NOTE: Reinforcing steel must be strong in tension and, at the same time, be ductile enough to be shaped
or bent cold.
III. TENSILE TEST
Steel reinforcing bar, or rebar, is embedded in concrete to improve the overall strength of the
concrete that surrounds it. Material products standards exist to help ensure that rebar produced
throughout the world exhibits the same physical, chemical, and mechanical properties regardless of the
source. Proper mechanical testing is then necessary for determining if the rebar meets its published
specifications, ensuring the quality of the product.
Mechanical testing requirements for rebar can vary, but typically fall into the following basic test
categories: Tensile Bend Compression Fatigue.
Equipment Considerations
❖
Universal (Hydraulic) Testing Machine
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❖
Accommodating Bent Specimens
As the standards indicate, it is necessary to straighten rebar specimens prior to tensile testing.
As a result, many test pieces may still have a slight bend or non-linearity over their length. Therefore, it
is best if the load frame and grips are able to accommodate slightly bent specimens.
Uncoiled rebar exhibiting slight bends over length
Grips that mechanically clamp on center are recommended in order to maintain axial alignment
of the specimen. This helps improve alignment and eliminates the need to “reset” the grips between
tests.
❖
Specimen Deformations and Scaling Grip
Jaws (faces) must accommodate the deformations and scale that is common on the surface of
rebars specimens. Build-up of scale in the teeth of the jaws can lead to specimen slippage. Tooth
patterns that are too aggressive can cause premature specimen failures and may also prevent the
specimen halves from being easily removed after the test. Therefore, tooth profiles should allow scale
to fall away naturally or be easily brushed away between tests. They should also alleviate the chance of
failures that are caused by the grips. If the broken specimen halves remain stuck in the jaw faces, the
operator must dislodge them through use of a hammer or other means. This can reduce efficiency and
add to operator fatigue and frustration. The mechanical functions of the grips should also be protected
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against the falling scale. If scale is allowed to get between moving parts, critical surfaces can be galled
and lead to poor performance or grip failure. It is important to regularly remove scale from the testing
equipment to help prevent unnecessary wear and tear.
Violent Specimen Failures
❖
Because rebar specimens release a lot of stored energy during tensile failure, the testing system
must be able to withstand the shock that results from the specimen recoil. The grips are impacted the
most and must be robust enough to absorb the energy and still hold the broken specimen halves so they
do not eject from the testing frame. Flying specimen pieces could become a safety hazard to the operator
and result in damage to the equipment. For all of these reasons, hydraulically actuated grips (wedge or
side-acting) are recommended.
#18 (57 mm) bar separation (recoil) after failure
Testing Speeds and Control
One of the more challenging aspects of complying with test standards is determining how to
properly and efficiently execute the tensile test. Despite standards providing specific details for
allowable test speeds and control modes for the different stages of the test, it can still be difficult to
perform the test properly. This may relate to both standard interpretation challenges and the
limitations of the test equipment.
For rebar tensile testing, it is helpful to break down the tensile test into the separate stages of
the test. This applies regardless of which test standard is being followed.
▪
The 5 basic regions are:
• Pretest
• Preload
• Elastic Region
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•
•
❖
Yielding
Plastic Region
Pretest
During the pretest stage, the machine is made ready for testing. The proper grips are installed and
test opening adjustments are made. Prior to installing the specimen, the force (load) measurement
should be set to zero.
Once the specimen is loaded into the system, the force should NOT undergo any further “zeroing”
as this will affect the test results. If using a manual extensometer for measuring strain, it should be
attached to the specimen making sure to properly set the knife edges at the instrument’s gauge length.
The strain measurement should then be set to zero prior to loading the specimen.
❖
Preload
The preloading stage is used to apply a minimal preload (<5% of expected yield strength) to the
specimen in order to properly seat it in the grips and to also aid in pulling the specimen straight prior
to testing. A plot of stress or force versus crosshead or actuator displacement will typically show
significant displacement for a minimal increase in load due to the grips and load string pulling tight
(taking up system compliance). If a preload is not applied and an extensometer is being used, many
rebar specimens will show negative strain at the beginning of the test as the specimen straightens.
Because of this and/or system compliance, the data during the preloading portion of the test is often
ignored or not recorded on the Stress-Strain graph.
Depending on the amount of system compliance or slack that was taken up (reduced) during the
preload, it may be necessary or desirable to zero the strain measurement at the end of preloading.
However, caution must be taken so as to not adversely affect the overall strain measurement. In either
case, test results that rely on strain from the extensometer should be adjusted so any non-linear
behaviour at the very beginning of the test curve does not adversely affect any test results. This is
addressed under the Linear Slope section of results.
❖
Elastic Region (before Yielding)
The elastic region or straight line portion of the test as seen on the Stress-Strain plot can often
exhibit some non-linear behavior initially due to further straightening of the rebar specimen. If using
an extensometer, this may show up as slightly negative strain at the beginning of the test and is
generally considered normal for rebar. Depending on the standard being followed, a variety of test
control and target speeds are allowed during the elastic region and until the onset of yielding. The
control and associated rate used may depend on the equipment limitations or specific product being
tested.
❖
Yielding
Once yielding begins, many rebar grades exhibit a defined yield point that is seen as an abrupt
bend in the Stress-Strain test curve. It is then followed by a period of specimen elongation with little to
no increase in force. Because of this, servo-controlled systems must be controlled using crosshead or
actuator displacement feedback in order to maintain a constant rate of travel throughout yielding.
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It is very important to note that using stress control during yielding will cause the test to
accelerate excessively, which is in direct violation of the standards. This can also cause the yield point
(upper yield) to be masked or smoothed and cause yield strength results to be higher than expected.
Likewise, strain control from an extensometer can also become erratic during yielding and, is therefore,
not recommended when testing rebar.
Elastic and Yielding regions of a rebar Stress-Strain curve
❖
Plastic Region (after Yielding)
As the standards clearly define, it is acceptable for the test speed to be increased after yielding has
completed. For servo-controlled machines, the best way to control the test during this final region is
from crosshead or actuator displacement feedback (same as yielding). However, the speed used can be
increased according to the standard being followed. This allows for the test to complete in a shorter
period of time while still producing acceptable and repeatable results.
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Target test rates for rebar test regions
•Results Nomenclature
Test standards incorporate terms, result names, and symbols to properly identify critical
information sought during testing.
It is very important to fully understand this information in order to ensure standards compliance
and proper results reporting. If testing to multiple standards, it is also necessary to understand the
similarities and differences between these items. In some cases, standards organizations can use
different terms or result names to refer to the same property. The following table shows a few common
examples of results that are found in ISO and ASTM standards. You can see from the table where there
are similarities and also differences.
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Common rebar tensile results for ISO and ASTM
•Results – No Extensometer
For lower grade bars that exhibit a distinct yield point, it is possible to perform the entire test
without the use of an extensometer. The yield point can be determined from the stress-extension test
curve by locating the first point at which stress drops while extension continues to increase.
On older testing systems, the yield point can be determined manually from witnessing the momentary
drop of the load pointer and calculating the stress from this load value and the nominal cross- sectional
area of the bar.
•Results – With Extensometer
Many higher grades of rebar do not exhibit a distinct yield point. In this case it is usually
necessary to determine the yield strength from the offset method. This requires measuring strain with
an extensometer and plotting a Stress-Strain curve from which a 0.2% offset yield strength (Rp 0.2) can
be determined. Most modern testing systems are capable of automatically generating the yield strength.
However, it is important to verify and validate the test method setup to make sure it is delivering
consistent and accurate yield strength results. The following areas should be of particular focus.
•Linear Slope
The test standards describe various approaches for fitting a line to the linear portion of the test
curve. This line is meant to represent the slope of the elastic region of the curve and can intersect the
strain axis somewhere other than the origin due to grips seating and the load string pulling tight as
described previously in the Preload section. Since the yield strength is dependent on both the slope of
this line and its x-intercept, it is critical that the setup is done properly. The following graph (fig. 10)
shows a properly defined linear slope and the corresponding offset yield strength (Rp0.2).
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Improper setup of this slope line could lead to incorrectly failing or passing material due
to inaccurate yield strength results! The graph in fig. 11 includes the same test plot as that in fig. 10.
However, the line defining the linear slope is not fit properly to the test curve and the corresponding
offset yield strength (Rp0.2) is reported higher than it should be.
•Yield Strength – Offset Method (Rp0.2)
The most common offset used for determining the yield strength of rebar is 0.2%. As the
standards clearly describe, the offset line is drawn parallel to the line representing the linear or elastic
region of the graph and is offset from the x intercept of this line. In order to ensure a proper offset, it is
necessary to measure strain accurately all the way through yield. Anything that adversely affects the
strain reading - such as improper instrument setup or slippage during the test - could directly affect the
yield strength result. Improper test control during yielding can result in yield strengths that are too
high. As described previously, acceleration during yielding violates the test standards. More
importantly, acceleration or test speeds in excess of those allowed by the standards can lead to elevated
yield strength values. This is less obvious on rebar grades that do not normally produce a distinct yield
point and can make it easy to incorrectly pass otherwise failing material. Avoid this type of risk by
confirming proper test control is established.
•Elongation
When using an extensometer, it may be possible to record elongation results, such as Agt or %
Elongation after fracture (A5), directly from the strain measurement. This can help automate the
recording of elongation results and eliminate the need for marking the specimen and taking manual
measurements after the test.
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When determining Agt automatically, the extensometer must remain attached through
maximum force. The total strain at the maximum stress point can then be reported automatically by the
system testing software. It can also be automatically adjusted to the x-intercept of the linear slope line.
However, if the extensometer is a manual type device that needs to be removed before failure, it can be
quite dangerous to require the operator to remove it after maximum force occurs. Many grades of rebar
will exhibit violent failure shortly after maximum force is achieved. Automatic extensometers provide
the added benefit of automatic removal at any point during the test. This protects the operator and
possibly the instrument while still allowing for automatic capture of Agt.
When automatically determining % Elongation after fracture, typically the extensometer must
be left on through fracture. Strain is then recorded at the break point determined at the end of the test.
The test software must also be able to subtract off the elastic portion of strain to make the result more
comparable to the manual method. This is dependent on the standard being followed. If the fracture
occurs too close to the knife edge, the elongation results will be lower than expected and may not pass.
TENSION TEST OF STRUCTURAL STEEL
REFERENCED STANDARD: ASTM E8
Objectives:
•To determine the tensile strength of a steel sample
•To examine/evaluate the elastic and inelastic behavior of the tested steel under given load
conditions.
•To describe the pattern of failure of the tested steel.
•To plot the stress-strain diagram for the tested specimen.
Apparatus/Materials:
•Universal Testing Machine
•Mechanical and Electronic Extensometer
•Micrometer
Procedure:
1.) Measure the dimensions of the specimen. Mark each quarter point along the length of the steel bar.
2.) Determine and record the average cross-sectional dimensions of the specimen with a micrometer.
3.) Secure the ends of the specimen in the UTM.
4.) Switch on the UTM. Set gage dials to zero. Apply increments of the load slowly until the specimen
fails. Record the applied load and corresponding elongation for each increment load.
5.) Remove the failed section. Measure. Observe the fracture pattern. Put the broken parts together
and measure the dimensions of tested specimen.
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CHARACTERISTICS AND PHYSICAL PROPERTIES OF WOOD
❖ Hardness - is the quality or state of being hard.
The hardness of a wood is rated on an industry wide standard known as the Janka test. The Janka
test measures the force required to embed a .444 inch steel ball into the wood by half its diameter.
❖ Conductivity - is the measure of the ease at which an electric charge or heat can pass through a
material.
In the direction of the grain, the thermal conductivity of wood is about twice what it is
perpendicular to the grain. For example, the thermal conductivity of pine in the direction of the grain
is 0.22 W/moC, and perpendicular to the grain 0.14 W/moC.
❖ Density - is a measure of mass per volume.
The density of wood differs from type to type depending on the tree growth environment, tree
species, and the tree area measured for density calculation. Fast growing trees have a low density.
Older and slowly growing trees have a higher wood density.
❖ Warping - is to bend or twist out of shape, especially from a straight or flat form, as timbers or
flooring.
▪ Types of Warping
•
•
•
•
•
Bow – Wood warps along the length of the lumber bending the thinnest face in a curve.
Crook- Wood warps along the length of the lumber bending the thicker face in a curve.
Kink – Wood warps along the width of the lumber producing a pronounced kink in the
straight face.
Cup – Wood warps along the length of the lumber with the two long edges cupping towards
each other.
Twist/wind – Wood warps along the length of the lumber with either end twisting in
opposing directions.
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❖ Cracking - the process of breaking into smaller units, especially the process of splitting a large heavy
hydrocarbon molecule into smaller, lighter components. Splits and cracks (known as ‘checks’ in the
industry) occur when wood shrinks as it dries.
❖ Swelling - is an increase of the dimensions of wood due to changes of its moisture content.
Swelling occurs as the wood changes moisture content in response to daily as well as seasonal
changes in the relative humidity of the atmosphere. When the air is humid, wood adsorbs moisture
and swells; when the air is dry, wood loses moisture and shrinks.
❖ Internal stress - is a stress existing within the material as a result of thermal changes, having been
worked, or irregularity of molecular structure.
❖ Color - the aspect of any object that may be described in terms of hue, lightness, and saturation.
❖ Luster - refers to how light is reflected from the surface of a mineral.
❖ Texture - is the quality of something that can be known by touch, or the degree to which something
is rough or smooth or soft or hard.
Textures might be divided into two categories, namely, tactile and visual textures.
▪ Tactile textures - refer to the immediate tangible feel of a surface.
▪ Visual textures - refer to the visual impression that textures produce to human observer.
❖ Odor - is anything you can smell like a scent or an aroma.
Example of Odorous Woods:
▪ Cocobolo: Technically a true member of the rosewood genus (Dalergia), Cocobolo also has a
pleasing spicy scent that has been used in perfume.
▪ Lignum Vitae: This tree, along with its Argentinian variant, is harvested in the production of
oil of guaiac, an ingredient in perfumes.
▪ Sandalwood: Reported to retain its scent for decades, essential oils from the wood are also
extracted and used in perfumes.
❖ Moisture - refers to the presence of a liquid, especially water.
The equilibrium moisture content of wood is a state corresponding to the air
temperature
and relative moisture, in which the moisture content of the wood remains steady.
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TESTING REQUIREMENTS
“Standard Test Methods for Small Clear Specimens of Timber”
REFERENCED STANDARD: ASTM D 143-94 (REAPPROVED 2000)Є1
1) SCOPE
a) These methods cover the determination of various strength and related properties of wood by
testing small clear specimens.
b) These methods represent procedures for evaluating the different mechanical and physical
properties, controlling factors such as specimen size, moisture content, temperature, and rate of
loading.
c) The procedures for the various tests are the following:
• Photographs of Specimens
• Control of Moisture Content and Temperature
• Record of Heartwood and Sapwood
• Static Bending
• Compression Parallel to Grain
• Impact Bending
• Toughness
• Compression Perpendicular to Grain
• Hardness
• Shear Parallel to Grain
• Cleavage
• Tension Parallel to Grain
• Tension Perpendicular to Grain
• Nail Withdrawal
• Specific Gravity and Shrinkage in Volume
• Radial and Tangential Shrinkage
• Moisture Determination
• Permissible Variations
• Calibration
2) Summary of Methods
a) The mechanical tests are static bending, compression parallel to grain, impact bending
toughness, compression perpendicular to grain, hardness, shear parallel to grain, cleavage,
tension parallel to grain, tension-perpendicular to-grain, and nail-withdrawal tests.
b) In addition, methods for evaluating such physical properties as specific gravity, shrinkage in
volume, radial shrinkage, and tangential shrinkage are presented.
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3) Photographs of Specimens
a) Four of the static bending specimens from each species shall be selected for photographing, as
follows: two average growth, one fast growth, and one slow growth. These specimens shall be
photographed in cross section and on the radial and tangential surfaces. Fig. 1 is a typical
photograph of a cross section of 2 by 2-in. (50 by 50-mm) test specimens, and Fig. 2 is the
tangential surface of such specimens.
FIG. 1 Cross Sections of Bending Specimens Showing Different Rates of Growth of Longleaf Pine
by 2-in. (50 by 50-mm) Specimens)
(2
FIG. 2 Tangential Surfaces of Bending Specimens of Different Rates of Growth of Jeffrey Pine (2 by 2in. (50 by 50 by 760-mm) Specimens)
4) Control of Moisture Content and Temperature
a) In recognition of the significant influence of temperature and moisture content on the strength
of wood, it is highly desirable that these factors be controlled to ensure comparable test results.
b) Control of Moisture Content
i) Specimens for the test in the air-dry condition shall be dried to approximately constant
weight before test.
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ii) Should any changes in moisture content occur during final preparation of specimens, the
specimens shall be reconditioned to constant weight before test
iii) it is desirable that the testing room and rooms for preparation of test specimens have some
means of humidity control.
5) Record of Heartwood and Sapwood
a) Proportion of Sapwood
i) The estimated proportion of sapwood present should be recorded for each test specimen.
6) Static Bending
a) Size of Specimens
i) The static bending tests shall be made on 2 by 2 by 30 in. (50 by 50 by 760 mm) primary
method specimens or 1 by 1 by 16 in. (25 by 25 by 410 mm) secondary method specimens.
The actual height and width at the center and the length shall be measured.
b) Loading Span and Supports
i) Use center loading and a span length of 28 in. (710 mm) for the primary method and 14 in.
(360 mm) for the secondary method. These spans were established in order to maintain a
minimum span-to-depth ratio of 14.
ii) Both supporting knife edges shall be provided with bearing plates and rollers of such
thickness that the distance from the point of support to the central plane is not greater than
the depth of the specimen.
FIG. 3 Static Bending Test Assembly Showing Method of Load Application, Specimen Supported on
Rollers and Laterally Adjustable Knife Edges, and Method of Measuring Deflection at Neutral Axis by
Means of Yoke and Dial Attachment (Adjustable scale mounted on loading head is used to measure
increments of deformation beyond the dial capacity.)
c) Bearing Block
i) A bearing block of the form and size of that shown in Fig. 4 shall be used for applying the load
for primary method specimens. A block having a radius of 11⁄2 in. (38 mm) for a chord
length of not less than 2 in. (50 mm) shall be used for secondary method specimens.
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FIG. 4 Details of Bearing Block for Static Bending Tests
d) Placement of Growth Rings
i) The specimen shall be placed so that the load will be applied through the bearing block to the
tangential surface nearest the pith.
e) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.10 in. (2.5 mm)/min, for primary method specimens, and at a rate of 0.05 in.
(1.3 mm)/min for secondary method specimens.
f) Load-Deflection Curves
i) Load-deflection curves shall be recorded to or beyond the maximum load for all static
bending tests.
g) Description of Static Bending Failures
i) Static bending (flexural) failures shall be classified in accordance with the appearance of the
fractured surface and the manner in which the failure develops (Fig. 6). The fractured
surfaces may be roughly divided into “brash” and “fibrous”, the term “brash” indicating
abrupt failure and“ fibrous” indicating a fracture showing splinters.
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FIG. 6 Types of Failures in Static Bending
7) Compression Parallel to Grain
a) Size of Specimens
i) The compression-parallel-to-grain tests shall be made on 2 by 2 by 8 in. (50 by 50 by 200
mm) primary method specimens, or 1 by 1 by 4 in. (25 by 25 by 100 mm) secondary method
specimens. The actual cross-sectional dimensions and the length shall be measured
b) End Surfaces Parallel
i) ensure that the end grain surfaces will be parallel to each other and at right angles to the
longitudinal axis.
ii) At least one platen of the testing machine shall be equipped with a spherical bearing to obtain
uniform distribution of load over the ends of the specimen.
c) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.003 in./in. (mm/mm) of nominal specimen length/min
d) Load-Compression Curves
i) Load-compression curves shall be taken over a central gage length not exceeding 6 in. (150
mm) for primary method specimens, and 2 in. (50 mm) for secondary method specimens.
e) Position of Test Failures
i) In order to obtain satisfactory and uniform results, it is necessary that the failures be made
to develop in the body of the specimen. With specimens of uniform cross section, this result
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can best be obtained when the ends are at a very slightly lower moisture content than the
body.
f) Descriptions of Compression Failures
i) Compression failures shall be classified in accordance with the appearance of the fractured
surface. In case two or more kinds of failures develop, all shall be described in the order of
their occurrence; for example, shearing followed by brooming. The failure shall also be
sketched in its proper position on the data sheet (see fig. 10) .
g) Weight and Moisture Content
i) The specimen shall be weighed immediately before test, and after the test a moisture section
approximately 1 in. (25 mm) in length shall be cut from the specimen near the point of failure.
h) Ring and Latewood Measurement
i) When practicable, the number of rings per inch (average ring width in millimetres) and the
proportion of summerwood shall be measured over a representative inch (centimetre) of
cross section of the test specimen.
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8) Impact Bending
a) Size of Specimens
i) The impact bending tests shall be made on 2 by 2 by 30 in. (50 by 50 by 760 mm) specimens.
The actual height and width at the center and the length shall be measured
b) Loading and Span
i) Use center loading and a span length of 28 in. (710 mm).
c) Bearing Block
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i) A metal tup of curvature corresponding to the bearing block shown in Fig. 4 shall be used in
applying the load.
d) Placement of Growth Rings
i) The specimen shall be placed so that the load will be applied through the bearing block to the
tangential surface nearest the pith.
e) Procedure
i) Make the tests by increment drops in a Hatt-Turner or similar impact machine (see Fig. 11).
The first drop shall be 1 in. (25 mm), after which increase the drops by 1 in. increments until
a height of 10 in. (250 mm) is reached. Then use a 2 in. (50 mm) increment until complete
failure occursor a 6 in. (150 mm) deflection is reached.
f) Weight of Hammer
i) A 50 lbf (22.5 kg) hammer shall be used when, with drops up to the capacity of the machine
(about 68 in. (1.7 m) for the small Hatt-Turner impact machine), it is practically certain that
complete failure or a 6 in. (150 mm) deflection will result for all specimens of a species. For
all other cases, a 100 lbf (45 kg) hammer shall be used.
g) Deflection Records
i) When desired, graphical drum records giving the deflection for each drop and the set, if any,
shall be made until the first failure occurs. This record will also afford data from which the
exact height of drop can be scaled for at least the first four falls.
h) Drop Causing Failure
i) The height of drop causing either complete failure or a 6 in. (150 mm) deflection shall be
observed for each specimen.
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i) Description of Failure
i) The failure shall be sketched on the data sheet and described in accordance with the
directions for static bending in 8.7.
j) Weight and Moisture Content
i) The specimen shall be
ii) weighed immediately before test, and after the test a moisture section approximately 1 in.
(25 mm) in length shall be cut from the specimen near the point of failure
9) Toughness
a) Size of Specimen
i) The toughness tests shall be made on 0.79 by 0.79 by 11 in. (20 by 20 by 280 mm) specimens.
The actual height and width at the center and the length shall be measured
b) Loading and Span
i) Center loading and a span length of 9.47 in. (240 mm) shall be used. The load shall be applied
to a radial or tangential surface on alternate specimens.
c) Bearing Block
i) An aluminum tup (Fig. 15) having a radius of 3⁄4 in. (19 mm) shall be used in applying the
load.
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d) Apparatus and Procedure
i) Make the tests in a pendulum type toughness machine (Note 7) (See Fig. 15). Adjust the
machine before test so that the pendulum hangs vertically, and adjust it to compensate for
friction. Adjust the cable so that the load is applied to the specimen when the pendulum
swings to 15° from the vertical, so as to produce complete failure by the time the downward
swing is completed. Choose the weight position and initial angle (30, 45, or 60°) of the
pendulum, so that complete failure of the specimen is obtained on one drop. Most satisfactory
results are obtained when the difference between the initial and final angle is at least 10°.
e) Calculation
i) The initial and final angle shall be read to the nearest 0.1° by means of the vernier (Fig. 15)
attached to the machine
ii) The toughness shall then be calculated as follows:
f) Weight and Moisture Content
i) The specimen shall be weighed immediately before test, and after test a moisture section
approximately 2 in. (50 mm) in length shall be cut from the specimen near the failure
10)Compression Perpendicular to Grain
a) Size of Specimens
i) The compression-perpendicular to-grain tests shall be made on 2 by 2 by 6 in. (50 by 50 by
150 mm) specimens. The actual height, width, and length shall be measure
b) Loading
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i) The load shall be applied through a metal bearing plate 2 in. (50 mm) in width, placed across
the upper surface of the specimen at equal distances from the ends and at right angles to the
length (Fig. 17). The actual width of the bearing plate shall be measured.
c) Placement of Growth Rings
i) The specimens shall be placed so that the load will be applied through the bearing plate to a
radial surface.
d) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.012 in. (0.305 mm)/mi
e) Load-Compression Curves
i) Load-compression curves shall be taken for all specimens up to 0.1 in. (2.5 mm) compression,
after which the test shall be discontinued. Compression shall be measured between the
loading surfaces.
ii) Deflection readings shall be taken to 0.0001 in. (0.002 mm).
f) Weight and Moisture Content
i) The specimen shall be weighed immediately before test, and after test a moisture section
approximately 1 in. (25 mm) in length shall be cut adjacent to the part under load
11)Hardness
a) Size of Specimens
i) The hardness tests shall be made on 2 by 2 by 6 in. (50 by 50 by 150 mm) specimens. The
actual cross-sectional dimensions and length shall be measured
b) Procedure
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i) Use the modified ball test with a “ball” 0.444 in. (11.3 mm) in diameter for determining
hardness (Fig. 19). The projected area of the ball on the test specimen is 1 cm2. Record the
load at which the ball has penetrated to one half its diameter, as determined by an electric
circuit indicator or by the tightening of the collar against the specimen.
c) Number of Penetration
i) Two penetrations shall be made on a tangential surface, two on a radial surface, and one on
each end. The choice between the two radial and between the two tangential surfaces shall
be such as to give a fair average of the piece. The penetrations shall be far enough from the
edge to prevent splitting or chippin
d) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.25 in. (6 mm/min)
e) Weight and Moisture Content
i) The specimen shall be weighed immediately before the test, and after the test a moisture
section approximately 1 in. (25 mm) in length shall be cut.
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12)Shear Parallel to Grain
a) This section describes one method of making the shear-parallel-to-grain test that has been
extensively used and found satisfactory.
b) Size of Specimens
i) The shear-parallel-to-grain tests shall be made on a 2 by 2 by 21⁄2in. (50 by 50 by 63 mm)
specimens notched in accordance with Fig. 21 to produce failure on a 2 by 2 in. (50 by 50
mm)surface. The actual dimensions of the shearing surface shall be measured
c) Procedure
i) Use a shear tool similar to that illustrated in Fig. 22, providing a 1⁄8 in. (3 mm) offset
between the inner edge of the supporting surface and the plane of the adjacent edge of the
loading surface. Apply the load to and support the specimen on end-grain surfaces. Take care
in placing the specimen in the shear tool to see that the crossbar is adjusted, so that the edges
of the specimen are vertical and the end rests evenly on the support over the contact area.
Observe the maximum load only.
d) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.024 in. (0.6 mm)/min
e) Test Failures
i) The failure shall be sketched on the data sheet In all cases where the failure at the base of
the specimen extends back onto the supporting surface, the test shall be culled.
f) Moisture Content
i) Moisture Content—The portion of the test piece that is sheared off shall be used as a moisture
specimen
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13)Cleavage
a) Size of Specimens
i) The cleavage tests shall be made on specimens of the form and size in accordance with Fig.
24. The actual width and length at minimum section shall be measured
b) Procedure
i) The specimens shall be held during test in grips as shown in Figs. 25 and 26. Observe the
maximum load only.
c) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.10 in. (2.5 mm)/min
d) Sketch of Failure
i) The failure shall be sketched on the data sheet
e) Moisture Content
i) One of the pieces remaining after failure, or a section split along the surface of failure, shall
be used as a moisture specimen
14)Tension Parallel to Grain
a) Size of Specimens
i) The tension-parallel-to-grain tests shall be made on specimens of the size and shape in
accordance with Fig. 28. The specimen shall be so oriented that the direction of the annual
rings at the critical section on the ends of the specimens, shall be perpendicular to the greater
cross-sectional dimension. The actual cross-sectional dimensions at minimum section shall
be measured.
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b) Procedure
i) Fasten the specimen in special grips (Fig. 29). Deformation shall be measured over a 2 in. (50
mm) central gage length on all specimens. Take load-extension readings until the
proportional limit is passed.
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ii) Read deformations to 0.0001 in. (0.002 mm).
c) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.05 in (1mm)/min
d) Sketch of Failure
i) The failure shall be sketched on the data sheet
e) Moisture Content
i) A moisture section about 3 in. (76 mm) in length shall be cut from the reduced section near
the failure
15)Tension Perpendicular to Grain
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a) Size of Specimens
i) The tension-perpendicular-to grain tests shall be made on specimens of the size and shape
in accordance with Fig. 31. The actual width and length at minimum sections shall be
measured
FIG. 31 Tension-Perpendicular-to-Grain Test Specimen
b) Procedure
i) Fasten the specimens during test in grips as shown in Figs. 32 and 33. Observe the maximum
load only.
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c) Speed of Testing
i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.10 in. (2.5 mm)/min
d) Sketch of Failure
i) The failure shall be sketched on the data sheet
e) Moisture Content
i) One of the pieces remaining after failure or a section split along the surface of failure, shall
be used as a moisture specimen.
16)Nail Withdrawal
a) Nails
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i) Nails used for withdrawal tests shall be 0.0985 in. (2.5 mm) in diameter (Note 16). Bright
diamond-point nails shall be used. All nails shall be cleaned before use to remove any coating
or surface film that may be present as a result of manufacturing operations. Each nail shall
be used once.
Note 16: A five penny common nail meets this requirement. If difficulty is experienced with highdensity woods in pulling the nails without breaking the heads, a seven penny cement-coated sinker
nail with coating removed by use of a suitable solvent, may be used.
b) Preparation of Specimens
i) Nails shall be driven at right angles to the face of the specimen to a total penetration of 11⁄4
in. (32 mm). Two nails shall be driven on a tangential surface, two on a radial surface, and
one on each end. The choice between the two radial and two tangential surfaces shall be such
as to give a fair average of the piece. On radial and tangential faces, the nails shall be driven
a sufficient distance from the edges and ends of the specimen to avoid splitting. In general,
nails should not be driven closer than 3⁄4 in. (19 mm) from the edge or 11⁄2 in. (38 mm)
from the end of a piece. The two nails on a radial or tangential face should not be driven in
line with each other or less than 2 in. (50 mm) apart.
c) Procedure
i) Withdraw all six nails in a single specimen immediately after driving. Fasten the specimens
during the test in grips as shown in Figs. 35 and 36. Observe the maximum load only
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d) Speed of Testing
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i) The load shall be applied continuously throughout the test at a rate of motion of the movable
crosshead of 0.075 in. (2 mm)/min
e) Weight and Moisture Content
i) The specimen shall be weighed immediately before driving the nails. After the test, a
moisture section approximately 1 in. (25 mm) in length shall be cut from specimen.
17)Specific Gravity and Shrinkage in Volume
a) Size of Specimens
i) The specific gravity and shrinkage in volume tests shall be made on green 2 by 2 by 6 in. (50
by 50 by 150 mm) specimens. The actual cross-sectional dimensions and length shall be
measured
b) Procedure:
i) Obtain both specific gravity and shrinkage-involume determinations on the same specimen.
Make these determinations at approximately 12 % moisture content and at the oven-dry
condition
ii) A carbon impression of the end of the green specimen may be made on the back of the data
sheet In like manner, a carbon impression of the same end may be made after the specimen
has been conditioned.
iii) Weigh the specimen when green and determine the volume by the immersion method in
accordance with the procedures of Test Methods D 2395.
iv) Open-pile the green specimens after immersion and allow them to air-season under room
conditions to a uniform moisture content of approximately 12 %. The specimens should then
be weighed and the volume determined by the immersion method.
v) Then, open-pile the specimens used for specific gravity and shrinkage determinations at 12
% moisture content, or duplicate specimens on which green weight and volume
measurements have been made prior to conditioning to approximately 12 % moisture
content in an oven. Dry at 103 6 2°C until approximately constant mass is reached (Test
Methods D 4442).
vi) After oven-drying, weigh the specimens and while still warm, immerse them in a hot paraffin
bath, taking care to remove them quickly to ensure a thin coating.
vii) Determine the volume of the paraffin-coated specimen by immersion as before.
viii) Fig. 39 illustrates the apparatus used in determining the specific gravity and shrinkage in
volume. The use of an automatic balance will facilitate increased rapidity and accuracy of
measurements.
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FIG. 39 Specific Gravity and Shrinkage-in-Volume Test Set-Up
ix) The green specimens shall be open-piled and allowed to air-season under room conditions
to a uniform moisture content of approximately 12 %.
x) After weighing and measuring, the specimens shall then be open-piled in an oven and dried
at 103 6 2°C until approximately constant mass is attained (Test Methods D 4442).
c) Final Measurement
i) Measurements of mass and length shall be made on the oven-dry specimens
d) Method of Measurement
i) Fig. 41 illustrates the method of making the radial and tangential shrinkage measurements.
An ordinary micrometer of required accuracy is suitable for this work
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FIG. 41 Radial- and Tangential-Shrinkage Test Assembly
18)Radial and Tangential Shrinkage
a) Size of Specimens
i) The radial and tangential shrinkage determinations shall be made on green 1 by 4 by 1 in.
(25 by 100 by 25 mm) specimens cut from 1 by 4-in. (25 by 100-mm) boards, edge grain and
flat grain, respectively.
b) Initial Measurement
i) The length of all specimens shall be measured.
c) Weight
i) The specimen shall be weighed when green and after subsequent oven-drying
d) Drying
i) The green specimens shall be open-piled and allowed to air-season under room conditions
to a uniform moisture content of approximately 12 %.
ii) After weighing and measuring, the specimens shall then be open-piled in an oven and dried
at 103 6 2°C until approximately constant mass is attained (Test Methods D 4442).
e) Final Measurement
i) Measurements of mass and length shall be made on the oven-dry specimens
f) Method of Measurement
i) Fig. 41 illustrates the method of making the radial and tangential shrinkage measurements.
An ordinary micrometer of required accuracy is suitable for this work
19)Moisture Determination
a) Selection
i) The sample for moisture determinations of each test specimen shall be selected as described
for each test.
b) Weighing
i) Immediately after obtaining the moisture sample, all loose splinters shall be removed and
the sample shall be weighed
c) Drying
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i) The moisture samples shall be open-piled in an oven and dried at a temperature of 103 6 2°C
until approximately constant mass is attained, after which the oven-dry mass shall be
determined
d) Moisture Content
i) The loss in mass, expressed in percent of the oven-dry mass as determined, shall be
considered the moisture content of the specimen.
20)Mass and Permissible Variations
a) Mass
i) The mass of test specimens and of moisture samples shall be determined to an accuracy of
not less than 0.2 %.
b) Measurements
i) Measurements of test specimens shall be made to an accuracy of not less than 0.3 %, except
that in no case shall the measurements be made to less than 0.01 in. (0.25 mm). However,
measurements of radial and tangential shrinkage specimens shall be made to the nearest
0.001 in. (0.02 mm).
c) Testing Machine Speeds
i) The testing machine speed used should not vary by more than 25 % from that specified for a
given test. If the specified speed cannot be obtained, the speed used shall be recorded on the
data sheet. The crosshead speed shall mean the free-running or no-load speed of crosshead
for testing machines of the mechanical drive type and the loaded crosshead speed for testing
machines of the hydraulic loading type.
21)Calibration
a) All apparatus used in obtaining data shall be calibrated at sufficiently frequent intervals to
ensure accuracy
22)Precision and Bias
a) Statements of precision and bias for the tests have not yet been developed.
Determination of the Moisture Content of Wood
REFERENCED STANDARD: ASTM D 144-83
Introduction
Moisture content of wood affects its strength. Prior to its use in construction, wood must be free
from objectionable defects and free from moisture that will cause it to shrink further develop cracks.
Determination of moisture content in wood helps in quantifying the amount of water in it and help
determines to what degree of seasoning is required to render it suitable for building construction. This
test uses drying as a means to determine the amount of moisture present in a wood sample.
Objectives:
1. To determine the moisture content of a wood sample.
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2. To understand the influence of moisture content to wood strength
Apparatus/Materials:
⚫
Oven
⚫
Wood sample
⚫
Weighing Balance
⚫
Ruler
Procedures:
1.
2.
3.
4.
Prepare a sample for moisture content determination.
Weigh the sample including its loose splinters.
Dry the sample in an oven at a temperature 103+2°C until it reaches a constant weight.
Weigh the oven-dried sample.
Data Analysis:
w = (Mw-Md)/Md x 100%
Where:
w = moisture content
Mw = mass of the wood before drying (grams)
Md = mass of the wood after drying (grams)
Percent Reduction in Volume = (V1 - V2)/V2 x 100%
Where:
V1 = original volume (cm³)
V2 = final volume (cm³)
Results:
Moisture content _______________________________________________________
Percent Reduction in Volume ___________________________________________
Discription of apperance after drying ____________________________________
LABORATORY NUMBER 15
TEST FOR COMPRESSIVE STRENGTH OF WOOD PARALLEL TO THE GRAIN
REFERENCED STANDARD : ASTM D 143- 83/ASTM D 198
INTRODUCTION
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Wood has been used in building in a construction for a variety of purposes due to its lightness,
durability and strength. The strength of the wood has influenced by the structure of its grain. Tensile
resistance along the grain is much greater than the resistance between fibers. When subjected to
bending, a piece of wood having grains that run longitudinally has strong tensile and compressive
strength compared to cross-grain wood.
OBJECTIVES
1. To determine the strength of wood under compressive loading.
2. To evaluate the strength of the tested sample against the allowable strength of its kind.
APPARATUS
⚫
Testing machine
⚫
Load indicator
⚫
Bearing blocks
⚫
Ruler
⚫
Caliper
⚫
Wood samples
PROCEDURES
1. Prepare a wood block according to the specifications of the laboratory instructor. measure then
record the dimensions of the specimen to the nearest 0.01 inch.
2. Place the specimen in the testing machine.
3. Apply the load continuously until the specimen fails. Record the deformation for each increment of
2000 lb load. Take simultaneous and deformation readings until the maximum load has been reached.
4. At the first sign of cracking, remove the strain device and continue loading until the maximum load
is recahed. Sketch the sample, indicating the grain wood and manner of failure.
DATA ANALYSIS
Compressive strength
Sc = P / A
Where:
Sc - compressive strength
P - total load in kg
A - bearing area (m^2 or mm^2) surface area perpendicular to load application.
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TEST FOR STATIC BENDING OF WOOD
REFERENCED STANDARD: ASTM D 143-83
INTRODUCTION
Lumber for construction use is classified according to appearance and strength. Most wooden
structural members are subjected to flexural and compressive forces, thus, must be tested for working
stresses.
Design codes require that structural wooden members be evaluated against allowable working
stresses. These allowable values take care of the unknown qualities that lumber may possess which
may affect its strength against tensile and compressive strength.
This test determines the physical properties of wood subjected to bending.
Objectives
1. To determine the maximum bending stress and the elasticity of a wood specimen
2. To evaluate the results of the tested specimen against the given properties of the same type of
wood
3. To examine and identify the type of failure of the tested specimen.
MATERIALS
•
•
•
•
•
Universal Testing Machine
Load Bearing Block
Wood Specimen 0.75m Long
Supporting Apparatus
Deflection Apparatus
PROCEDURE
1. Mark the center and end points of the specimen for a 0.75 m span.
2. Place the beam in the machine with the ends place on the supports and place the loading block
at the center of the beam (midpoint loading). The whole assembly shall be properly centered
such that the loading block is at the center of the machine’s loading head.
3. Lower the loading head until a small compressive load is apllied to the beam. Place the deflection
gage at the midspan in such a way that it can measure the midspan deflection of the beam. Set
the gage of the deflection and the testing machine to zero.
4. Apply the load continuously at the rate of 1.000 lb per min. Take simultaneous load and
deflection readings for increment of every 200 lbs until the maximum load has been reached.
Remove the dial gage prior to the failure of the beam.
5. Sketch the type of failure and plot load-deflection curve.
DATA ANALYSIS
1. Maximum Bending Stress
f= 3PmaxL/ 2bh^2
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Where:
F
=
maximum bending stress (MPa)
Pmax =
maximum load (MN)
L
=
length of specimen (m)
B
=
width of the section (m)
D
=
depth of the section
2. Modulus of elasticity
E= PL/ A8= PL^3/48bd^3
Where:
P
=
maximum load (MN)
L
=
length of specimen (m)
b
=
width of the section (m)
h
=
height of the section
8
=
deflection (m)
TEST FOR TENSILE STRENGTH OF WOOD PARALLEL TO THE GRAIN
REFERENCED STANDARD : ASTM D 143-83
Tensile strength is the capability of a material to resist tearing. The resistance of material to a force
tending to tear it apart, measured as the maximum tension the material can endure without tearing.
The tensile strength of wood parallel to the grain depends upon the strength of the fibers and is affected
not only by nature and dimensions of the wood elements but also by their arrangement. The tensile
strength of wood is greater along the grain than across the grain.
Three types of wood:
⚫
Softwoods
⚫
Hardwoods
⚫
Engineered wood
Softwoods
Are the wood and lumber which are milled from conifer trees. Scientifically known as Gymnosperms,
Conifer trees are any trees which have needles and produce cones.
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Examples: Pine, Cedar, Fir, Spruce, and Redwood.
Hardwoods
Hardwoods come from any trees which do not produce needles or cones. These trees are most
commonly are known as deciduous trees, more scientifically known as angiosperms. Hardwoods are
trees which produces leaves and seeds.
Examples: Oak, Maple, Cherry, Mahogany, and Walnut.
Engineered Wood: Manufactured Wood Products
Engineered wood does not occur naturally in the environment but instead are manufactured.
These boards are generally made with wood which is manipulated to have certain qualities or
features. Also known as composite wood, these products are often made from the waste wood of
sawmills. It is often treated through chemical or a heat process to produce a wood product which can
meet certain sizes that would be difficult to achieve from nature.
Popular examples of engineered woods include Plywood, Oriented Strand Board, Medium Density
Fiber Board, and Composite Board. Wood veneers can also sometimes be classified as engineered wood,
since it often needs to be manipulated either through specialized cutting techniques or joining pieces
together to achieve a specific size or wood grain patterning.
FAILURES:
⚫
Simple tension
⚫
Cross-grained tension
⚫
Splintering tension
⚫
Brittle tension
⚫
Compression failure
⚫
Horizontal shear failure
Simple tension
In which there is a direct pulling in two of the wood on the underside
Cross-grained tension
In which the fracture is caused by a tensile force acting oblique to the grain.
Splintering tension
In which the failure consist of a considerable number of slight tension failures.
Brittle tension
In which the beam fails by a clean break extending entirely through it.
Compression failure
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Compressive stress parallel to the fibers causes them to buckle or bend as in an ending compressive
test.
Horizontal shear failure
In which the upper and lower portions slide along each other for a portion of their length either at
one or at both ends.
OBJECTIVES:
1. To calculate the tensile strength of a wood sample
2. To evaluate the test result against the given allowable tensile stress of the same type of wood sample
3. To examine and describe the type and pattern of failure
APPARATUS/MATERIALS:
⚫
Tension apparatus
⚫
Strain gages
⚫
Grips
⚫
Wood samples
PROCEDURE:
1. Prepare the wood sample. Measure its dimensions.
2. Assemble the tension apparatus the place the wood sample in the grips.
3. Apply increments of load. Read and record the deformation at each increment of load.
4. Right before failure remove the deformation gage then continue loading until the specimen fails.
Sketch the type of failure.
DATA ANALYSIS:
Tensile Strength
P
St = A
Where: P = maximum load
A = load bearing area of wood( mm2 )
TEST FOR SHEAR STRESS OF WOOD PARALLEL TO GRAIN
REFERENCED STANDARD: ASTM D 143-83
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INTRODUCTION
Shearing of wood is common in wood subjected to loads along its grain. This test is used to
determine the shear stress of a wood section subjected to a load applied along the direction of its grain.
Objectives
1. To determine the shear strength of a wood sample.
2. To evaluate the test result of the sample against the given allowable shear
type of wood.
3. To examine and describe the type and pattern of failure.
stress of the same
MATERIALS
•
•
•
Compression Machine
Shear Apparatus
Wood Section
PROCEDURE
1. Assemble the shear apparatus and the compression machine.
2. Prepare the wood specimen. Record its dimensions.
3. Place the wood section in the shear apparatus.
4. Apply the load at a continuous rate. Observe the wood section at each increment of load. Sketch
the failure pattern.
DATA ANALYSIS
Shear Stress=
P/A
Where:
P= applied maximum load (kg)
A= Area of shear plane (mm)^2
Self-Help: You can also refer to the sources below to help you further understand the
lesson:
Kultermann E. and Spence, William. (2017). Construction Materials, Methods, and
Techniques: Building a sustainable future. 4th Edition. Australia: Cencage Learning
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Ahmed, A. and Sturges, J. (2015). Materials science in construction: an introduction.
Abingdon, Oxon; New York, NY: Routledge
Allen, E. and Iano, J. (2014). Fundamentals of Building Construction: Materials and
Methods. 6th Edition. Hoboken, New Jersey: Wiley
Let’s Check Activity 1. Now that you know some types and properties of common
construction materials let us try to check how far you had learned. In the space provided,
write the term/s being asked in the following statements.
___________1. It separates the iron from the waste materials and sinters the ore and flue dusts.
___________2. is the medium stage cast iron which properties are in between gray cast iron and
white cast iron.
___________ 3. The world’s foremost construction material that contains between 0.2% and 2%
carbon by weight and sometimes small amounts of other elements, including manganese.
___________ 4. It is ASTM Standard Test Methods for Small Clear Specimens of Timber.
___________ 5. This is a kind of steel bar that is used in the form of strands or tendons.
___________ 6. A type of wood that are most commonly are known as deciduous trees, more
scientifically known as angiosperms.
__________ 7. The machine used for tensile test.
___________ 8. In the stress-strain diagram, it is the point in which the material will no longer go
back to its original shape when the load is removed.
___________ 9. An increase of the dimensions of wood due to changes of its moisture content.
____________ 10. In the stress-strain diagram, it is the point at which the material will have an
appreciable elongation without any increase in load.
Let’s Analyze
Activity 1. Getting acquainted with the types and properties of some common and
advanced construction materials. what also matters is you should also be able to explain
some its properties. Now, choose 5 most important properties of metals which you believe
are essential in determining its suitability for intended used in construction. Why?
Activity 2. Why is it important to determine the moisture content of wood?
In a Nutshell
Activity 1. The study of types and properties of construction materials such as steel and
woods, is indeed pre-requisite to becoming an engineer.
Based on the topics presented and learning exercises that you have done, why would you choose
structural steel as construction material. Please feel free to write your answer below. I have
indicated mine.
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1. It speeds up construction productivity.
2. Compared to other construction materials, it has a lower project cost.
Now it’s your turn.
3.
4.
5.
6.
7.
8.
9.
10.
Commented [CE3]: Provide are for “In a Nutshell” and
“Q&A”
Q&A List
Do you have any question for clarification?
Questions/Issues
Answers
1.
2.
3.
4.
5.
Keywords Index
Metals
Ferrous
Wrought Iron
Alloys
Non – Ferrous
Aluminum
Cast Iron
Copper
Reinforcing Steel
STANDARD EXPERIMENTS
Refer to Laboratory Manual
Experiment numbers 21 – 26
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Lead
Steel
Wood
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BIG PICTURE
Week 8 to 9: Unit Learning Outcomes - 4 (ULO - 4): At the end of the unit, you are expected to:
a. Demonstrate knowledge and understanding of the properties and behaviors of most common and
advance construction material such as asphalts.
b. Conduct/Familiarize the methods, procedures and formulas of different experiments on common
construction materials according to international standards such as ASTM & AASTHO.
Big Picture in Focus
ULO-4a. Demonstrate knowledge and understanding of the properties and behaviors of most
common and advance construction material such as asphalts or bituminous materials.
Metalanguage
This section deals with the study of different types and properties of construction materials such as
asphalts.
Please proceed immediately to the “Essential Knowledge.”
Essential Knowledge
To perform the aforesaid big picture (unit learning outcomes) for the next (2) weeks of the course, you
need to fully understand the following essential knowledge that will be laid down in the succeeding
pages. Please note that you are not limited to exclusively refer to these resources. Thus, you are
expected to utilize other books, research articles and other resources that are available in the
university’s library e.g. ebrary, search.proquest.com etc.
INTRODUCTION: ASPHALT OR BITUMINOUS MATERIALS
Bituminous materials
Bituminous materials or asphalts are extensively used for roadway construction, primarily
because of their excellent binding characteristics and water proofing properties and relatively low cost.
Bituminous materials is generally used to denote substances in which bitumen is present or from which
it can be derived. Bitumen is defined as an amorphous, black or dark-colored, (solid, semi-solid, or
viscous) cementitious substance, composed principally of high molecular weight hydrocarbons, and
soluble in carbon disulfide.
For civil engineering applications, bituminous materials include primarily of asphalts and tars.
Asphalts may occur in nature (natural asphalts) or may be obtained from petroleum processing
(petroleum asphalts). Tars do not occur in nature and are obtained as condensates in the processing of
coal, petroleum, oil-shale, wood or other organic materials. Pitch is formed when a tar is partially
distilled so that the volatile constituents have evaporated off from it. Bituminous mixtures are generally
used to denote the combinations of bituminous materials (as binders), aggregates and additives.
Classification of bituminous materials:
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Production of Bitumen
Bitumen is the residue or by-product when the crude petroleum is refined. A wide variety of
refinery processes, such as the straight distillation process, solvent extraction process etc. may be used
to produce bitumen of different consistency and other desirable properties. Depending on the sources
and characteristics of the crude oils and on the properties of bitumen required, more than one
processing method may be employed.
In the vacuum-steam distillation process the crude oil is heated and is introduced into a large
cylindrical still. Steam is introduced into the still to aid in the vaporization of the more volatile
constituents of the petroleum and to minimize decomposition of the distillates and residues. The
volatile constituents are collected, condensed, and the various fractions stored for further refining, if
needed. The residues from this distillation are then fed into a vacuum distillation unit, where residue
pressure and steam will further separate out heavier gas oils. The bottom fraction from this unit is the
vacuum-steam-refined asphalt cement. The consistency of asphalt cement from this process can be
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controlled by the amount of heavy gas oil removed. Normally, asphalt produced by this process is softer.
As the asphalt cools down to room temperature, it becomes a semi solid viscous material.
Different Forms of Bitumen
1. Cutback bitumen
-
is a range of binders that are produced by blending (mixing) penetration grade bitumen and a
hydrocarbon solvent, such as paraffin or mineral turpentine.
-
cutback bitumen gets its name from the solvent that is involved in the process, because the
solvent "cuts back" or evaporates, leaving behind the binder to "get on with the job".
-
the solvent used in cutback bitumen is called the "cutter" or "flux".
-
three types of solvents are used for the blending process: slow-curing, medium-curing or
rapid-curing solvents.
-
curing relates to the evaporation rate of the solvent which influences the setting time of the
bitumen. The viscosity of the cutback bitumen is determined by the proportion of solvent
added: the higher the proportion of solvent, the lower the viscosity of the cutback.
2. Bitumen Emulsion
-
is a mixture of fine droplets of bitumen and water. But as the bitumen is a petroleum product it
doesn’t mix with water and as it is sticky in nature, it doesn’t easily gets disintegrated into fine
droplets. To overcome this problem an emulsifier is used.
-
emulsifier can be defined as a surface-active agent. Emulsifier keeps the bitumen in its fine
droplet state by disallowing it to mix with other droplets.
-
three types of bituminous emulsions are available, which are Rapid setting (RS), Medium
setting (MS), and Slow setting (SC).
-
Rapid setting emulsions are used for surface dressing work. Medium setting emulsions are
preferred for premix jobs and patch repairs work. Slow setting emulsions are preferred in
rainy season.
3. Bituminous Primers
-
in bituminous primer the distillate is absorbed by the road surface on which it is spread. The
absorption therefore depends on the porosity of the surface.
-
Bitumen primers are useful on the stabilized surfaces and water bound macadam base courses.
-
Bituminous primers are generally prepared on road sites by mixing penetration bitumen with
petroleum distillate.
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4. Modified Bitumen
-
Certain additives or blend of additives called as bitumen modifiers can improve properties of
Bitumen and bituminous mixes. Bitumen treated with these modifiers is known as modified
bitumen.
-
Polymer modified bitumen (PMB)/ crumb rubber modified bitumen (CRMB) should be used
only in wearing course depending upon the requirements of extreme climatic variations.
-
The advantages of using modified bitumen are as follows:
o Lower susceptibility to daily and seasonal temperature variations.
o Higher resistance to deformation at high pavement temperature.
o Better age resistance properties.
o Higher fatigue life for mixes.
o Better adhesion between aggregates and binder.
o Prevention of cracking and reflective cracking.
Requirements of Bitumen
▪
The desirable properties of bitumen depend on the mix type and construction. In
general, Bitumen should possess following desirable properties.
o The bitumen should not be highly temperature susceptible: during the hottest
weather the mix should not become too soft or unstable, and during cold
weather the mix should not become too brittle causing cracks.
o The viscosity of the bitumen at the time of mixing and compaction should be
adequate. This can be achieved by use of cutbacks or emulsions of suitable
grades or by heating the bitumen and aggregates prior to mixing.
o There should be adequate affinity and adhesion between the bitumen and
aggregates used in the mix.
COMPOSITION OF ASPHALT
Asphalt Ingredients
There are actually two basic ingredients in asphalt. The first are aggregates; this is a mix of
crushed stone, gravel, and sand. Aggregates make up about 95% of hot mix asphalt pavement.The other
5% is bitumen. Bitumen is the black or dark viscous material that holds the aggregates together, and is
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composed of polycyclic hydrocarbons (a petroleum byproduct).For a deeper understanding of asphalt's
ingredients, the elemental components of asphalt include carbon, hydrogen, sulfur, oxygen, nitrogen,
and trace amounts of iron, nickel, and vanadium.There are actually several different types of asphalt,
and they are categorized by the process used to bind aggregate with the bitumen.
Asphalt Durability
If you've ever been jarred by a crack in an asphalt road, you know that the material doesn't last
forever. The performance of asphalt can vary widely depending on a number of variables that include the
presence of moisture, temperature fluctuations, volume of traffic, and exposure to certain chemicals.
Even varying asphalt ingredients can determine its durability.
Because asphalt can hold the weight of vehicles, it is the material of choice for roads, parking
lots, and driveways. It can be applied rapidly and can be patched easily by pressing it directly into cracks
and potholes.
Over time, asphalt ingredients can begin to erode and decay from heavy traffic, exposure to the
elements, and expansion and contraction. Because of this, the use of a sealcoat is absolutely essential to
the proper maintenance of any asphalt-paved surface. While there are a number of sealing products on
the market, we only recommend the use of coal tar asphalt sealer because of its ability to create an
effective buffer against traffic, water, oil salt, and other staining agents.
When asphalt ingredients aren't properly protected with a coat of sealer, they will inevitably
crack. Leaving even small cracks and fissures exposed and unrepaired will definitely lead to more
serious damage such as potholes, crumbling asphalt, and foundation damage. This ultimately results in
the need for costly asphalt replacement.
Asphalt's Most Effective Maintenance Strategy
For homeowners, it's important to understand the ingredients in asphalt because it does need
to be maintained on a regular schedule. An asphalt driveway can remain in good condition for decades
if it is properly cared for.
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Knowing what can negatively affect asphalt ingredients is also important. Since oil, grease, gas,
salt, and transmission fluid can break down the quality of asphalt and ultimately result in cracking and
crumbling, these substances should be cleaned up quickly if spilled on asphalt.
Crack Filling
As part of preventative maintenance, asphalt should be inspected for cracks. Even small, hairline
fissures that go unrepaired or unfilled can cause the ingredients in asphalt to deteriorate. With all types
of asphalt, a certain amount of cracking is inevitable. The secret is to fill the cracks before they expand
and turn into potholes or larger areas of crumbling pavement. There are two types of crack filler that
can be used on any asphalt or concrete surface. Cold liquid pour asphalt crack fill is high effective in
sealing cracks up to ½” in width. The product is easy to use and keeps cracks on all types of asphalt
sealed for several years.
Hot pour crackfill is commercial-grade rubberized asphalt crack sealer that works on cracks up
to 1” in width. It can be safely heated in a kettle or crack fill applicator melter and poured into cracks to
seal out water, ice, and debris. It will keep cracks sealed for up to four years.
Sealcoating
All asphalt types require proper maintenance and proactive repair to retain their appearance
and overall condition. Because of the nature of asphalt ingredients, driveways should be sealed every
two to three years to prevent oxidation, loss of flexibility, cracking, and crumbling. At Asphalt Kingdom,
we recommend the use of coal tar sealer which protects the bitumen from oxidizing, becoming brittle,
and cracking. It is easy to apply with either a spray system or a squeegee and dries quickly in three to
four hours.
Desirable Properties of Aggregates Selection of an aggregate material for use in an Asphalt
Concrete pavement depends on the availability, cost, and quality of the material, as well as the type of
construction for which it is intended. To determine if an aggregate material is suitable for use in asphalt
construction, evaluate it in terms of the following properties:
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1. Size and grading. The maximum size of an aggregate is the smallest sieve through which 100 percent
of the material will pass. How the Asphalt Concrete is to be used determines not only the maximum
aggregate size, but also the desired gradation (distribution of sizes smaller than the maximum).
2. Cleanliness. Foreign or deleterious substances make some materials unsuitable for paving mixtures.
3.Toughness. Toughness or hardness is the ability of the aggregate to resist crushing or disintegration
during mixing, placing, and compacting; or under traffic loading.
4.Soundness. Although similar to toughness, soundness is the aggregate’s ability to resist deterioration
caused by natural elements such as the weather.
5.Particle shape. The shapes of aggregate particles influence the asphalt mixture’s overall strength and
workability as well as the density achieved during compaction. When compacted, irregular particles
such as crushed stone tend to “lock” together and resist displacement.
6.Surface texture. Workability and pavement strength are influenced by surface texture. A rough,
sandpapery texture results in a higher strength than a smooth texture. Although smooth-faced
aggregates are easy to coat with an asphalt film, they are generally not as good as rough surfaces. It is
harder for the asphalt to “grip” the smooth surface.
7.Absorption. The porosity of an aggregate permits the aggregate to absorb asphalt and form a bond
between the particle and the asphalt. A degree of porosity is desired, but aggregates that are highly
absorbant are generally not used.
8.Stripping. When the asphalt film separates from the aggregate because of the action of water, it is
called stripping. Aggregates coated with too much dust also can cause poor bonding which results in
stripping. Aggregates readily susceptible to stripping action usually are not suitable for asphalt.
KINDS AND USES OF ASPHALT
I.
Porous Asphalt
Porous asphalt has been around since the mid 1970s. This type of asphalt is used in parking lots to
enable water to drain through the pavement.
II. Perpetual Pavement
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Perpetual pavement is a multi-layer paving process designed for heavy loads and incorporates a strong,
flexible base to prevent, a strong permanent middle layer and the smooth top driving surface.
III. Hot Mix Asphalt
Hot mix asphalt is used for driveways, producing a strong, durable surface that is easy to repair and
maintain, withstands freezing and thawing.
IV. Warm-mix Asphalt
Warm-mix asphalt is produced the same way that hot-mix asphalt is, except it is 50-100 degrees
Fahrenheit lower. Reducing the temperature of the asphalt has a few benefits. These include reducing
fuel consumption and the production of greenhouse gases.
V. Quiet asphalt
Quiet asphalt is used to reduce the amount of noise pollution created by traffic on roads that are built
through or near residential areas.
VI. Thin overlays
Thin overlays improve ride quality and reduce pavement distress, noise levels, and life-cycle costs. It is
produced by using warm-mix asphalt and recycled materials.
Uses of Asphalt
The primary use (70%) of asphalt is in road construction, where it is used as the glue or binder mixed
with aggregate particles to create asphalt concrete.
a. Road Construction
Smooth asphalt reduces the friction between tires and roads, which means better fuel economy and
reduced carbon dioxide emissions.
b. Bituminous Waterproofing
Its other main uses are for bituminous waterproofing products, including production of roofing felt and
for sealing flat roofs.
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OTHER PRODUCT MADE WITH BITUMINOUS MATERIALS
Coal Tar Pitch
Coal tar pitch is dark brown to black hydrocarbon
obtained through the distillation of coke-oven tar. It is
available in several grades and is used as the basis for
number
of
paints,
roofing
products,
a
and
waterproofing materials. It has softening point near
150°F (65°C).
Coal tar pitch enamel is made from coal tar pitch with added minerals fillers. It is used
to protect pipe in pipeline work. Cold-applied coal tar products have a solvent added
to liquefy them. Hot-applied coal tar coatings give better protection than cold coal tar
coatings.
Felts
Felt is a sheet material made from the cellulose
fibers of organic
materials such as wood, paper, rags, glass fibers,
and asbestos.
Saturated felts, sometimes called tar paper, are
made
organic mat saturated with a layer of thin asphalt.
Tar paper is used
with
an
as an underlayment for shingles, as sheathing paper. And as limitations in built-up roof construction.
Tar paper is also used to produced roll roofing and shingles.
Ice and Water Shield
Ice and water shield is a roofing membrane composed of two
waterproofing materials bonded into one layer. Comprised of a
rubberized asphalt adhesive backed by a layer polyethylene. The
rubberized asphalt is backed by a release paper to protect the sticky
The material is used as waterproofing in cavity walls, and for
trouble spots on roofs, such as long eaves, in valleys and in others
areas where leaks are more likely.
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Fiberglass Sheet material
Fiberglass mats can be impregnated with asphalt but are not
because the glass fibers will not absorb the asphalt. The asphalt
“saturated”
forms
a
coating on the surface and fills the spaces between the fibers.
Fireproofing Paper
Fireproofing paper is made using asbestos
fibers either
in a pressed mat-liked felt or in a woven
sheet.
various
sheet
products
are
used
The
as
underlayment for finished roofing materials,
as
vapor
barriers in walls and floors, and for other
similar
applications. They should not be exposed to
the weather
because coal tar pitch oxidizes rapidly when
subjected to
the sun’s ultraviolet rays.
Waterproof Coatings
Asphalt waterproofing is used on masonry walls above
and
below
grade. Below grade, it is used to resist the pressure of
subsurface
water and prevent it from passing through the
foundation. As
it is not subjected to high temperatures below grade,
asphalts with
lower softening points can be used. Above grade, it
resists
passage of water through walls or roof decking. Where
it
exposed to sunlight, asphalts with a higher softening
point
be utilized.
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be
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A bituminous waterproofing coating is applied in one or more coats mopped on either hot and cold.
Cold-applied coats can be reinforced by the addition of glass, plastic, or asbestos fibers. Cutbacks and
emulsion are used extensively for this purpose. They may be covered with a plastic or felt membrane.
A damp-roofing board product is made with an
asphalt core
covered on both sides by layers of asphalt-
impregnated
paper or felt treated with a weather-resistant
coating.
BITUMINOUS ROOF COVERING
The various types of bituminous roof-covering materials in common use. It should be noted that coal
tar pitch and asphalt are not compatible and should not be used where they will come in contact with
each other.
Roll Roofing
Roll roofing uses either organic felt or fiberglass mats as a base material. A viscous bituminous coating
is applied to this base, forming the exposed surface. Roll roofing is made in four types: smooth surfaced,
mineral surfaced, mineral surfaced selvage edged, and pattern edged. Smooth-surfaced roll roofing has
both sides covered with a fine talc or mica to keep the surfaces from sticking as it is made into rolls.
Mineral-surfaced roll roofing has mineral granules in a wide range of colors rolled into the surface,
producing a surface that is attractive and protects the bitumen from sun’s ultraviolet rays. The mineral
also increased the fire resistance of the product.
Hot Bitumen Built-Up Roof Membrane
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A built-up roof consists of alternate
plies
if
organic or fiberglass roofing felt with
a hot bitumen
coating mopped over each layer. The
design of the
roof varies by situation but generally
consist
of
three or more layer of felt with a
bitumen
layer over each and a bitumen topcoat
with
aggregate rolled on top.
Felts
provide
the
needed
reinforcement to keep bitumen in
each
layer
from alligatoring. “Alligatoring” refers
to
surface
cracking caused by oxidation and shrinkage stresses, which can result in a repetitive mounding of the
asphalt surface similar to an alligator’s hide.
Modified Asphalt Roofing Systems
Modified
is
composed of
polymer-modified bitumen reinforced
asphalt
roll
roofing
with one or
more plies of fabric, such as polyester
glass
These membranes are of uniform
thickness and
have consistent physical properties
throughout
fiber.
the membrane area.
A variety of modifiers and types of
reinforcing
plies are designed for use on almost
every type of
construction assembly, including new roofing, re-roofing, domes, and spires. Modified membrane are
also used below grade for waterproofing canals, water reservoirs, and landfills.
Most-modified bitumen membranes are made using either styrene-butadiene-styrene (SBS) or atactic
poly-propylene (APP). APP-modified membranes are generally using a propane torch to heat and soften
the underside of the membrane. This surface becomes a molten adhesive that is placed on the substrate,
rolled for adhesion, and bonds when it cools. SBS modifies the bitumen membranes by forming a
polymer lattice within the bitumen. When this polymer lattice cools, the membrane acts like a rubber.
SBS membranes are more flexible than APP membranes and are used where flexibility is needed, such
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as when the substrate may be subject to movement or deflection. SBS-modified membranes are mopped
in hot asphalt, self-adhered, or adhered with cold-process adhesives. Some types can have their joint
heat-welded. Some have factory-applied mineral aggregates surfaces to protect them from ultraviolet
damage. Those without this covering need some form of ultraviolet protective coating.
Cold-Applied
Asphalt
Roofing
System
Cold-applied systems use some form of coated base sheet, fabric, or similar reinforcement over which
the principal waterproofing agent, which is applied at ambient temperature. The selection of the coldprocess application depends on the level of maintenance, repair, and service expected, and on the
compatibility between the cold-applied materials and any existing substrate
The reinforcing felts and fabrics
organic-coated
sheets,
organic
mineral-surfaced cap sheets,
organic felt
sheets, fiberglass ply sheets,
fiberglass
base sheet, fiber glass mineral-
surfaced cap
sheet
s,
base
include
single-ply
smooth
surfaced
fiberglass
fabrics,
polyester
fabric, cotton fabric, and jute
burlap
sheets,
fabric. The base sheet, cap sheet,
and
ply roofing are bonded with
cold-applied
adhesives
coatings
and
to
cold-applied
forms
a
singlesurface
roof
membrane.
The coating and adhesives are designed to be brushed or sprayed at normal room temperatures. These
include filled and non-filled asphalt cutbacks, asphalt emulsion, coal tar coatings, and aluminum
pigmented asphalt. Toppings include gravel and aluminum chips places in the topcoat while it is still
wet. They block ultraviolet light, can reflect heat, and are decorative.
DIFFERENCE BETWEEN ASPHALT AND BITUMEN
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Bitumen is the liquid binder that holds asphalt together. A bitumen-sealed surface is a layer of
bitumen sprayed and then covered with an aggregate. This is then repeated to give a two-coat seal.
Asphalt is produced in a plant that heats, dries and mixes aggregate, bitumen and sand into a
composite.
The process flow of any asphalt plant will depend on the type of the plant. There are two major
types / categories: batch type and continuous type.
1.CONTINUOUS ASPHALT PLANT PROCESS FLOW
The starting point of the asphalt drum mix plant process is the continuous feeding of cold aggregates
into the feeder bins. Aggregates have to be fed as per the size into different feeder bins. The number of
bins are three, four or even more. The flow of aggregates from individual bins are controlled as
required by the mix material design. This flow is also controlled and regulated from the control panel.
Primary vibrating screen will screen the over sized material and aggregates will enter the drum for
heating and then mixing. The drum mixer will evenly apply heat to the aggregates and then coat it
uniformly with bitumen as aggregates pass from one end of the drum. The drum unit is inclined and
rotating that facilitates easy flow of aggregates from one end to the other. Fuel for bitumen tank drum
burner is stored in a separate tank.
Bitumen and filler material are the ones that are added into the drum for mixing with aggregates.
Bitumen is stored in separate tanks and then added into the drum by a pipe line by a bitumen pump
controlled by a variable speed drive motor. Filler material is stored in separate filler hopper and
transferred by means of a compressor.
Pollution control is taken care by dry and wet type pollution control devices. After proper mixing, the
hot mix is discharged to the other end of the drum and onto a conveyor. This conveyor takes the HMA
into the waiting trucks or storage silos. All these processes are controlled by a computerized control
panel that comes with the asphalt mix plant.
2.BATCH ASPHALT PLANT PROCESS FLOW
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The process or flow for the asphalt plant – batch type starts the same way as we have to feed the
aggregates into separate feeder bins. The aggregates then pass through a primary vibrating screen
that helps in removal of oversized material. After that the aggregates are treated to heat in a drum
which is fitted with a burner unit.
Dust suction is done at the entry point of the aggregates into the drum and the dust absorbed is
treated by pre-separator and then by a bag filter unit.
The heated aggregates are then transferred to the top of mixing tower into the vibrating screen.
Vibrating screen has screens of different sizes laid out for separation of aggregates. After separation,
aggregates are stored into different bins as per their size. This area is called hot bins and it is just
below the vibrating screens.
On the other hand, bitumen which is stored in the storage tanks is transferred to the weigh hopper
near the mixing unit. Same happens for filler material as it gets transferred to its weigh hopper.
Aggregates will be weighed and then discharged into the mixing unit by opening of pneumatic
cylinders as set in the control panel. Bitumen and filler material are also added by weight into the
mixing unit to complete the batch. Batch mixing time is set in the control panel and after the mixing
time is over, the pneumatic gates below the mixing unit will open leading to the discharge of hot mix
asphalt into the storage silo or directly into waiting trucks.
BATCH PLANTS
This is the most widespread type of asphalt plant in the world, which guarantees the highest level of
flexibility in production and quality of the finished product. The batches depend on the type of
production: every 40-50 seconds a complete batch is produced, after all the individual components
have been weighed and metered separately.
This type of plant is a must for producers who work for several clients at the same time, because the
specifications can be easily changed, while maintaining a high level of quality.
CONTINUOUS PLANTS
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In continuous plants there is no interruption in the production cycle as the rhythm of production is
not broken into batches. The mixing of the material takes place inside the dryer drum which is
elongated, as it dries and mixes the material at the same time.
Since there are no mixing tower or elevators, the system is therefore considerably simplified, with a
consequent reduction in the cost of maintenance.
The absence of the screen however makes it necessary to have precise controls at the beginning of the
production cycle, before the aggregates are fed into the dryer and before they are consequently
discharged from the dryer as asphalt.
AGGREGATE METERING
In both types of plant, the production cycle begins with the cold feeders, where the aggregates are
generally metered by volume; if required, the sand extractor can be fitted with a weigh-belt for
metering.
Control of the total weight of the virgin aggregates, however, is effected in two different phases of the
production cycle in the two different plants. In the continuous type there is a feed belt, before the
moist aggregates are fed into the dryer drum, where the moisture content is set manually in order to
allow for the weight of water to be subtracted. Therefore it is extremely important for the moisture
content in the aggregates, particularly the sand, to have a constant value which is continually
monitored through frequent laboratory tests.
In batch type plants the weight of the aggregates is checked after drying, before they are fed into the
mixer. The weighing, therefore, in the weigh hopper is not influenced by moisture or by variable
factors, such as changeable weather conditions.
Furthermore, in batch type plants, the presence of the screen means there is more accuracy in the
selection of materials before mixing, therefore making the quality of the finished product more
consistent. Inaccuracies are also avoided – such as large aggregates ending up by mistake in the sand
hopper, or inconsistencies in the supply of aggregates, or possible errors preset in the formula at the
cold feeders.
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For this reason, in the specifications of many countries, where quarries do not enforce adequate and
strict control procedures required for the production of asphalt, batch type plants are a compulsory
requirement.
BITUMEN METERING
In batch type asphalt plants the bitumen is metered by weight through load cells in the weigh hopper.
The computer system ensures that the exact quantity is fed into the mixer, calculated on the basis of
the specifications and the actual weight of the aggregates.
In continuous plants the metering is generally volumetric through a litre-counter subsequent to the
feed pump. Alternatively, it is possible to install a mass counter, a necessary choice if modified
bitumen is used, which requires frequent cleaning operations.
FILLER METERING
In batch plants, the filler is metered by weight in the weigh hopper, where the recovered fines and
imported fines can be separately controlled, thereby making the metering process very precise. The
filler is then fed into the mixer with its own screw conveyor or by gravity.
In continuous plants the metering system is normally volumetric, using variable-speed feed screws
which have replaced the previous pneumatic metering system.
In the end it is the client’s decision to whether use the batch or the continuous asphalt mixing plant.
LABORATORY TESTS FOR BITUMINOUS MATERIALS
◼
QUALITY TEST
Lab Tests On Bitumen To Check Quality
Various tests are conducted on bitumen to assess its consistency, gradation, viscosity, temperature
susceptibility, and safety.
There are a number of tests to assess the properties of bituminous materials. The following tests are
usually conducted to evaluate different properties of bituminous materials.
1. Penetration test
2. Ductility test
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3. Softening point test
4. Specific gravity test
5. Viscosity test
6. Flash and Fire point test
7. Float test
8. Water content test
9. Loss on heating test
Penetration Test
It measures the hardness or softness of bitumen by measuring the depth in tenths of a millimeter to
which a standard loaded needle will penetrate vertically in 5 seconds. BIS had standardized the
equipment and test procedure.
The penetrometer consists of a needle assembly with a total weight of 100g and a device for releasing
and locking in any position. The bitumen is softened to a pouring consistency, stirred thoroughly and
poured into containers at a depth at least 15 mm in excess of the expected penetration. The test
should be conducted at a specified temperature of 250C.
It may be noted that penetration value is largely influenced by any inaccuracy with regards to pouring
temperature, size of the needle, weight placed on the needle and the test temperature.
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In hot climates, a lower penetration grade is preferred. The Fig-1 shows a schematic
Penetration Test setup.
Fig-1 Penetration Test Setup
Ductility Test
Ductility is the property of bitumen that permits it to undergo great deformation or elongation.
Ductility is defined as the distance in cm, to which a standard sample or briquette of the material will
be elongated without breaking. Dimension of the briquette thus formed is exactly 1 cm square. The
bitumen sample is heated and poured in the mould assembly placed on a plate. These samples with
moulds are cooled in the air and then in water bath at 270C temperature. The excess bitumen is cut
and the surface is leveled using a hot knife. Then the mould with assembly containing sample is kept
in water bath of the ductility machine for about 90 minutes. The sides of the moulds are removed, the
clips are hooked on the machine and the machine is operated. The distance up to the point of breaking
of thread is the ductility value which is reported in cm.
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The ductility value gets affected by factors such as pouring temperature, test temperature, rate of
pulling etc.A minimum ductility value of 75 cm has been specified by the BIS. Fig-2 shows ductility
Test Process.
Fig-2 Ductility Test
Softening Point Test
Softening point denotes the temperature at which the bitumen attains a particular degree of softening
under the specified condition of test.
The test is conducted by using Ring and Ball apparatus. A brass ring containing test sample of bitumen
is suspended in liquid like water or glycerin at a given temperature. A steel ball is placed upon the
bitumen sample and the liquid medium is heated at a rate of 50C per minute. Temperature is noted
when the softened bitumen touches the metal plate which is at a specified distance below.
Generally, higher softening point indicates lower temperature susceptibility and is preferred in hot
climates. Fig-3 shows Softening Point test setup.
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Fig-3 Softening Point Test Setup
Specific Gravity Test
The specific gravity of bitumen is defined as the ratio of mass of given volume of bitumen of known
content to the mass of equal volume of water at 270C. The specific gravity can be measured using
either pycnometer or preparing a cube specimen of bitumen in semi solid or solid state.
In paving jobs, to classify a binder, density property is of great use. In most cases bitumen is weighed,
but when used with aggregates, the bitumen is converted to volume using density values.
The density of bitumen is greatly influenced by its chemical composition. Increase in aromatic type
mineral impurities cause an increase in specific gravity.
The specific gravity of bitumen varies from 0.97 to 1.02.
Viscosity Test
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Fig-4 Viscosity Test
Viscosity denotes the fluid property of bituminous material and it is a measure of resistance to flow.
At the application temperature, this characteristic greatly influences the strength of resulting paving
mixes.
Low or high viscosity during compaction or mixing has been observed to result in lower stability
values. At high viscosity, it resists the compactive effort and thereby resulting mix is heterogeneous,
hence low stability values. And at low viscosity instead of providing a uniform film over aggregates, it
will lubricate the aggregate particles.
Orifice type viscometers are used to indirectly find the viscosity of liquid binders like cutbacks and
emulsions.
The viscosity expressed in seconds is the time taken by the 50 ml bitumen material to pass through
the orifice of a cup, under standard test conditions and specified temperature. Viscosity of a cutback
can be measured with either 4.0 mm orifice at 250C or 10 mm orifice at 25 or 400C.
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Flash and Fire Point Test
At high temperatures depending upon the grades of bitumen materials leave out volatiles. And these
volatiles catch fire which is very hazardous and therefore it is essential to qualify this temperature for
each bitumen grade. BIS defined the ash point as the temperature at which the vapour of bitumen
momentarily catches fire in the form of ash under specified test conditions. The fire point is defined as
the lowest temperature under specified test conditions at which the bituminous material gets ignited
and burns.
Float Test
Normally the consistency of bituminous material can be measured either by penetration test or
viscosity test. But for certain range of consistencies, these tests are not applicable and Float test is
used.
The apparatus consists of an aluminum oat and a brass collar filled with bitumen to be tested. The
specimen in the mould is cooled to a temperature of 50C and screwed in to oat. The total test assembly
is floated in the water bath at 500C and the time required for water to pass its way through the
specimen plug is noted in seconds and is expressed as the oat value.
Water Content Test
It is desirable that the bitumen contains minimum water content to prevent foaming of the bitumen
when it is heated above the boiling point of water.
The water in bitumen is determined by mixing known weight of specimen in a pure petroleum
distillate free from water, heating and distilling of the water. The weight of the water condensed and
collected is expressed as percentage by weight of the original sample.
The allowable maximum water content should not be more than 0.2% by weight.
Loss on Heating Test
When the bitumen is heated it loses the volatility and gets hardened. About 50gm of the sample is
weighed and heated to a temperature of 1630C for 5 hours in a specified oven designed for this test.
The sample specimen is weighed again after the heating period and loss in weight is expressed as
percentage by weight of the original sample.
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Bitumen used in pavement mixes should not indicate more than 1% loss in weight, but for bitumen
having penetration values 150-200 up to 2% loss in weight is allowed.
Different Methods of Grading of Bitumen
Following are the different methods used for grading of bitumen
1. Grading by chewing
2. Penetration grading
3. Viscosity grading
4. Superpave performance grade
Grading of Bitumen by Chewing
During the 19th century, chewing was the method used to determine the stiffness i.e. hardness if the
bitumen. This was the time when no penetration test was developed. It was carried out by
experienced US inspectors. Based on the test conducted, the sample was either accepted or rejected.
The temperature of bitumen tested was such that, it favors human body temperature.
Penetration Grading of Bitumen
The American Society for Testing Materials (ASTM) D 04 carried out bitumen grading at a
temperature of 25 degree Celsius for the testing of the road and pavement materials in 1903.
The penetration test involves penetration of a needle that is loaded by 100g, into a bitumen sample
maintained at a temperature of 25-degree Celsius in a water bath for a period of 5 seconds. The
penetration value is measured in millimeters.
1 penetration unit = 0.1mm.
The greater the penetration value, the softer the bitumen become. The ASTM standard D 946 gives 5
penetration grades for the bitumen binders. They are:
1. Hardest Bitumen Grade 40 –50
2. 60 –70
3. 85-100
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4. 120-150
5. Softest Bitumen Grade 200-300
The penetration grading system is 100 years old bitumen grading method. In India, before 2006, the
most widely used grade of bitumen was 60 to 70. For the construction of low volume roads and to
perform spraying, penetration value from 80 to 100 was used.
Viscosity Grading of Bitumen
In the 1970s, US introduced the method of viscosity grading at 60 degree Celsius. This was to ensure a
solution for construction problems and to have high temperature performance. These were tender
mixes that must undergo mix pushing and shoving under the roller, without which it cannot be rolled
properly.
Prior to 1970s, the US construction used 60 to 70 penetration grade that shows variation towards
rutting action. They showed lower viscosity at 135 degree Celsius. This caused tender mix problems
during the construction process.
The viscosity test, unlike penetration grading, is a fundamental test carried out at 60 degree Celsius.
This temperature is the maximum temperature to which the road pavement is subjected to at
summer. The measurement is in terms of Poise.
In India, the equipment for testing the viscosity at 60 and 135 degrees are available. They are very
simple to handle with. In the US, Six Asphalt Cement (AC) viscosity grades were specified. They are,
Grade
Viscosity at 60 degree Celsius, Poises
AC -2.5 SOFTEST
250±/-50
AC-5
500±/-100
AC-10
1000±/-200
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AC-20
2000±/-400
AC-30
3000±/-600
AC-40 HARDEST
4000 ±/-800
In the US, Bitumen is mentioned as asphalt cement or asphalt. The grades with lower viscosity i.e. AC2.5 and AC-5 were used for cold service temperatures; areas like Canada. In Northern tier states, AC10 was used. Mostly in the US, AC-2- was used.
Only five grades excluding AC-30 was initially determined. These have a mean viscosity that will
double from grade to grade. This resulted in no overlap in viscosity range. But the problem of AC-20 to
be too soft and AC-40 to be too hard, that was faced by countries Florida, Georgia, and Alabama made
AC-30 to be incorporated and hence six grades.
The figure below shows the AC-30 bitumen viscosity grade which is equivalent to VG-30 in India
Fig.5: Graph representing temperature and stiffness (in terms of viscosity) relationship of AC-30 (VG30) Bitumen
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Superpave Performance Grading of Bitumen
The performance grading of bitumen is based on the evaluation of the material performance when in
use, unlike being rational as in viscosity grading system. The viscosity grading system is more into
experience based method of grading. And this has proved to have excellent performance for over 20
years in US pavement construction.
The Superpave grading was developed as a part of a 5year strategic highway research planning
(SHRP) from 1987 to 1992, to have a performance based grading system for bitumen. These were
developed based on the engineering features that will help in solving many of the engineering
problems.
Features of Superpave Performance Grading of Bitumen
The Superpave performance grading system make use of a new set of bitumen tests. The method
incorporates the following salient features:
•
The system includes tests and specification for bitumen binders. This bitumen binder may have
either modified or unmodified bitumen.
•
The field performance by the engineering principles will influence the physical properties
determined from the Superpave bitumen tests. That is, it is not achieved by experience alone.
•
The bitumen simulation for a period of 5 to 10 years, to understand its performance with age
was developed. This is a long-term bitumen aging test.
•
The tests and specification of Superpave system intend to avoid three main damages in
bitumen i.e. raveling, fatigue cracking and thermal cracking. These failures happen at high,
intermediate and low temperature respectively.
•
The pavement is taken for testing for the entire range of temperature as shown in the figure
below. A rotational viscometer is taken to determine the viscosity at 135 degree Celsius. The
viscoelastic property of bitumen at two temperatures is determined with the help of a dynamic
shear rheometer. The first temperature is “high temperatures” maximum 7-day temperature
during a hot summer day of the project site. The second one is “intermediate temperature”,
which is the average annual temperature of the pavement at the project site.
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•
During Winter a bending beam rheometer and direct tension tester are used to measure the
bitumen rheological properties at the project site.
Fig.6: The testing carried on the pavement at project site for entire range of temperature in a
Superpave grading system (As per FHWA)
The performance of Superpave is dependent on climate. The Superpave performance grade (PG) for
project location where the temperature during 7 days is greater than 64 degree Celsius and a
minimum temperature of -22 degrees are PG 64 to 22.
The available higher grades are PG 52, PG 58, PG 64, PG 70, PG 76 and PG 82. The lower grades are -4,
-10, -16, -22, -28, -34 and so on. Both the temperature levels increment at a rate of 6 degrees.
If in Rajasthan the project site has maximum 7-day record temperature of pavement as 70 degrees
and a minimum temperature of -3 degree, PG 70 to 4 bitumen will be specified for that project.
EXTRACTION METHOD
Bitumen Extraction test is used to determine the amount of bitumen that is actually used as binding
content in asphaltic pavement or asphaltic concrete recently laid at site. The durability, compatibility
and resistance from defects like rutting, bleeding, raveling and ageing of flexible asphaltic roads is
highly dependent on the amount of the bitumen used for the coating of the filler aggregates used in
the asphaltic matrix.
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So this test is parallel to that of the cylindrical compression test of the actual concrete samples
obtained at site before placement of concrete to determine its actual compressive strength to be as
per the required mix design.
The mix design of asphalt is carried out by series of hit and trial in job mix formula for determination of
the optimum binder content. So at site, before final payment to the contractor it must be ensured that
the amount of bitumen required by the mix design is actually used at site or not.
Apparatus for the Bitumen Extraction Test
The equipment needed for this test method are:
1. ) Oven a well maintained oven is needed cable of maintaining the temperature at 110 degrees.
2. ) A flat pan for carrying the test specimens.
3. ) Balance or scales capable of weighing the sample to an accuracy of 0.05 % of its mass.
4. ) Extraction apparatus, consisting of a bowl and an apparatus in which the bowl may be
revolved at controlled variable speeds up to 3600 revolutions per minute.
5. ) Filter ring or filter paper to fit in the trim of the bowl.
Generally there are two method used for the bitumen extraction test:
1.) Centrifuge Method
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2.) Extraction Bottle Method
In most parts of the world the first method i.e. Centrifuge Method is usually used so for today’s post I
would also be dealing only the Centrifuge method for Bitumen Extraction Test and is standardized by
American Society for Testing Materials ASTM 2172. This method actually uses the generic process of
cold solvent extraction method.
The background of this test is that a solvent is used to immerse the sample and then by centrifuging all
the bitumen is extracted / removed isolating the mineral aggregates. The weight of those aggregates is
subtracted from the total weight of the sample to get the weight of the bitumen in the sample expressed
as percentage binder content.
Bitumen Extraction Test by Centrifuge Method
1.) Sample Preparation
The sample can either be taken from the asphalt plant or from the dump truck at site depending on the
site situation. As the results obtained from the test sample may be affected by the age of the material;
thus for best results the test must be carried out on mixtures and pavement shortly after their
preparation.
If the sample is not soft enough so as to get separated by a spatula, it must be placed on a flat pan and
then warmed at a temperature of 1100C plus or minus 5 0C in the oven till it can be handled or
separated.
From that a representative sample is taken of the size in accordance with the nominal maximum size of
the aggregates in the mix. If the sample has aggregates of 4.75 mm than 0.5 kg of sample is sufficient
but if it had aggregates of 37.5 mm or so a 4 kg sample must be taken. As a guide you can follow this
table.
The sample taken is weighed to the nearest of 0.05% of its mass and is recorded as W1 and is then
placed in the bowl for the extraction machine.
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The sample is then immersed or covered with the solvent that can be petrol of about 5 liters or it is
better to add commercial grade tricholoroethylene or Benzene and let the mixture stand for about an
hour. The purpose of solvent is to disintegrate the test portion.
An oven dried filter ring is taken and its initial weight is recorded. The temperature of oven for drying
the ring is kept at 110 plus minus 50 The edge of the bowl is covered with this filter ring.
The bowl is then covered with a steel cover and is clamped tightly before placing in the apparatus. A
beaker or a clean container is placed underneath the drain outlet of the centrifuge apparatus for
collection of the extract (mixture of solvent and bitumen).
2.) Centrifuge the Sample
The next step is to centrifuge the apparatus, the bowl is placed in the apparatus and the machine is
started to revolve. The speed is gradually increased till a maximum speed of 3600 rev/min is attained.
The machine is allowed to revolve till solvent ceases to flow from the drain outlet.
Allow the machine to stop and additional solvent is added in quantity of 200 ml or more depending on
the amount of the sample.
The solvent is added again and again with minimum of 3 cycles till the color of extract coming out from
the drain outlet is clear and not darker than a light straw color.
The filter paper is carefully removed from the bowl or container along with the residual aggregate in a
metal pan; which is afterwards dried in air and in the oven at a constant temperature around 1100
The fine fragments of mineral aggregates that are attached with the filter are carefully scratched and
then the weight of the filter and aggregate are noted.
Calculations & Report
The bitumen content obtained as a result of the bitumen extraction test is calculated and reported as
follows:Bitumen content (grams) =( W1-(W2+W3))/W1
Where,
W1 = weight of the sample test portion in grams
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W2 = Weight of the extracted mineral aggregate in grams.
W3 = weight of the fine aggregate fragments in grams
Result :
The bitumen content may be expressed as a percentage of weight of bitumen with respect total weight
of the mix or with respect to total aggregate in the mix.
Bitumen content % by weight of total mix = (bitumen content in grams / W1) x 100
Precautions
This test may involve hazardous materials, operation and equipment. Safety precautions must be
exercised at all times. The inhalation of solvent fumes may be particularly harmful and therefore it is
advised that the area where the extraction test is carried out is well ventilated and that an adequate
extractor fan is provided.
Balances should be calibrated using reference weight once every twelve month.
Marshall Stability and Flow
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The Marshall test method is widely used for the design and control of asphaltic concrete and hot rolled
asphalt materials. It cannot be applied to open textured materials such as bitumen macadam. Materials
containing aggregate sizes larger than 20 mm, are liable to give erratic results.
The full Marshall method is a method of bituminous mix design in addition to being a quality control
test. The details given below related mainly to its use as a quality control test. The suitability of
materials for the design of Marshall asphalt requires that a number of tests are performed on the
materials.
Apparatus
The samples are prepared in 100 mm diameter moulds which are fitted with a base and collar (Figure
10.9.1) the sample is compacted using a hammer consisting of a sliding weight which falls onto a circular
foot (Figure 10.9.2) during compaction the mould is held on a hardwood block which is rigidly fixed to
a concrete base (Figure 10.9.3).
The sample is removed from the mould using an extraction plate and press (Figure 10.9.1) and heated
to the test temperature of 60° C in a water bath. The cylindrical specimens are tested on their sides
between test heads similar to those shown in Fig. 10.9.4. The flow is measured with a dial gauge and
the stability is measured with a proving ring. A motorised load frame is required for the test.
Sampling
Due to the various uses which may be made of Marshall tests, the materials for test may be obtained in
one of the following forms:
a) 100 mm diameter bituminous cores cut from an existing pavement using a core cutting machine.
b) Ready-mixed bituminous material obtained from a mixing plant or at the point of laying, and
sampled
c) A sample of mixed aggregate obtained from the mixing plant together with a separate sample of
bitumen obtained from the storage tank at the mixing plant.
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A sample of mixed aggregate may be obtained from a mixing plant by batching the specified aggregate
weights into the mixer but not allowing any bitumen to be batched. The aggregate sample is then
discharged into a clean lorry where it may be sampled in accordance with Chapter 2.d) Samples of the
various sized aggregates in use at the mixing plant sampled in accordance with Chapter 2 together with
a separate sample of bitumen sampled in accordance with Chapter 2. In the case of a sample of type (a),
the core may be tested without further preparation. It must, however, be of the correct diameter and
height.
It is doubtful if samples obtained in this manner give results which are closely comparable to laboratory
compacted specimens; however, the taking of cores is a valuable way to check the compacted density
of the ‘as laid’ material and the small amount of additional work in determining the stability and flow is
justified. If the densities obtained form cores (or sand replacement tests) are significantly below those
of laboratory compacted specimens, attention should be paid to the methods of laying and compacting.
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For many quality control purposes samples of type (b) are the most useful as they may be compacted,
after re-heating in an oven to the required temperature. The delay between initial mixing and
compacting should be as short as possible. With this type of sample separate test on the mixed aggregate
will be required to determine the void content. It is essential to make frequent checks on the combined
aggregate from an asphalt plant. The most important factors to be checked are the aggregate
temperature at the time of mixing and the grading of the mixed aggregate.
It may, therefore, be convenient to obtain separate samples of aggregate and bitumen (type (c) sample)
and mix them in the required proportions in the laboratory. As the aggregate will be discharged from
the mixer in a dry state, there is considerable risk of segregation and the greatest care should be taken
in obtaining a representative sample.
If there are reasons to suspect that the bitumen at the mixing plant has been overheated, it may be
worthwhile to check the penetration as excessive heating hardens the bitumen. One particular use of
this method of sampling is that if some adjustment is required to the bitumen content, a number of
samples may be made at various bitumen contents to determine which is the most satisfactory. To
maintain the quality of a bituminous material, it is necessary to check, at regular intervals, the various
sizes of aggregate for grading, cleanliness, shape, strength etc. If it is required to study the effects of
varying the aggregate, or bitumen proportions, it will be necessary to obtain separate samples of each.
Sample Preparation
If necessary, the aggregates should be oven-dried at 150°C before testing commences. (Sample types
(c) and (d)).
For samples of type (d) it is first necessary to combine the various sample sizes to give the required
grading for the mixed aggregate. Several different gradings may be tried if a full Marshall mix design is
to be carried out. When it is required to determine the most satisfactory bitumen content, given a
sample of mixed aggregate, an initial estimate of the required bitumen content can be made from a
knowledge of the compacted density of the Mixed Aggregate (CDMA).
The CDMA is most conveniently determined using a standard 100 mm. diameter compaction mould and
a 2.5 kg compaction hammer. The sample of dry aggregate is compacted in the mould in four layers,
each layer being given 20 blows of the hammer. The density of the aggregate is then calculated in an
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identical manner to the bulk density in a compaction tests. The average of two determinations is taken
as the CDMA, as shown in Form 10.9.1.
It is also necessary to carry out separate determinations of the specific gravity of the mixed aggregate
(SGMA), and the specific gravity of bitumen. The voids in mixed aggregate VMA are then determined
from the formula:
VMA CDMA SGMA= X(SGMA −100%
The VMA should normally be between 17 and 20% for a satisfactory mix. An initial estimate of the
optimum bitumen content (B) is obtained from the formulae :
BVMA VIM x S G Bitumen CDMA 100 ( − ) . .
Where, B100 is expressed in parts per 100 parts of mixed aggregate (p.h.a) and VIM = the specified
percentage of air voids in the compacted mix.
Note. In bitumen calculations, it is usual to express all densities and specific gravities in gram/ml;
gram/cc or Mg/cu.m. Having completed the required tests on the mixed aggregates, the bituminous
material is then produced by mixing the aggregates with the bitumen in the correct proportions.
Self-Help: You can also refer to the sources below to help you further understand the
lesson:
Kultermann E. and Spence, William. (2017). Construction Materials, Methods, and
Techniques: Building a sustainable future. 4th Edition. Australia: Cencage Learning
Ahmed, A. and Sturges, J. (2015). Materials science in construction: an introduction.
Abingdon, Oxon; New York, NY: Routledge
Let’s Check Activity 1. Now that you know some types and properties of common
construction materials let us try to check how far you had learned. In the space provided,
write the term/s being asked in the following statements:
______________1. It is a composite material made up of mineral aggregates and bitumen commonly used for
roads, parking lots and airports and also known as blacktop.
_____________ 2. HMA or hot mix asphalt is made of how many percent of aggregates?
_____________ 3. It influences the asphalt mixture’s overall strength and workability as well as the density
achieved during compaction.
____________ 4. This type of asphalt is used in parking lots to enable water to drain through the pavement.
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____________ 5. It is used for driveways, producing a strong, durable surface that is easy to repair and
maintain, withstands freezing and thawing.
____________ 6. It is a multi-layer paving process designed for heavy loads and incorporates a strong, flexible
base to prevent, a strong permanent middle layer and the smooth top driving surface.
____________ 7. Another main uses or primary use of asphalt, including production of roofing
felt and for sealing flat roofs.
____________ 8. This method is used to determine the amount of bitumen that is actually used as binding
content in asphaltic pavement or asphaltic concrete recently laid at site.
_____________ 9. In batch type asphalt plant, the bitumen is metered by what?
_____________ 10. It measures the hardness or softness of bitumen by measuring the depth in tenths of a
millimeter to which a standard loaded needle will penetrate vertically in 5 seconds.
Let’s Analyze
Activity 1. Getting acquainted with the types and properties of some common and
advanced construction materials. what also matters is you should also be able to explain
some its properties. Now, choose 5 most important properties of asphalt which you
believe are essential in determining its suitability for intended used in a road
construction. Why?
Activity 2. Why is it important to conduct Marshall Stability Test for Asphalt?
In a Nutshell
Activity 1. The study of types and properties of construction materials I such as asphalt
or bituminous materials very important.
Based on the topics presented and learning exercises that you have done, please feel free to
write some advantages of bituminous road construction over concrete pavement. I have
indicated my lessons learned.
1. It provides a smooth surface to ride.
2. It gives less sound emission when compared with concrete pavement.
Now it’s your turn.
3.
4.
Commented [CE4]: Provide are for “In a Nutshell” and
“Q&A”
5.
6.
7.
8
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9.
10.
Q&A List
Do you have any question for clarification?
Questions/Issues
Answers
1.
2.
3.
4.
5.
Keywords Index
Asphalt
Bituminous Material
Continuous Asphalt Plant
Aggregate Metering
STANDARD EXPERIMENTS
Refer to Laboratory Manual
Experiment numbers 27 – 28
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