Contents
MODULE 1:.............................................................................................................................................................................. 2
CONSTRUCTION MATERIALS AND TESTING....................................................................................................................... 2
PROPERTIES OF MATERIALS ............................................................................................................................................... 7
Module 2:................................................................................................................................................................................ 9
Metals ................................................................................................................................................................................. 9
CONCRETE ......................................................................................................................................................................... 21
MODULE 1:
CONSTRUCTION MATERIALS AND TESTING
INTRODUCTION:
Materials Testing- refers to the performance of tests on different construction materials
to determine
numerical values for properties
Control - to check, test, or verify by evidence or experiments
Significance of Materials and Testing and Control
1. Check and regulate the use of construction materials
2. Build structure in the most scientific and economical way
3. Promote better relationship among engineers, contractors, owners and manufacturers
because disputes that arise as to acceptability of the materials to be used or
delivered are avoided
4. The engineer can avoid hasty, haphazard, or even uncertain decisions during the
prosecution
of the work
1. Materials testing and research will enhance progress and development
2. Proper materials control ensures the highest quality of work and prolongs the
usable life Gf
any structure
7. Determine the type of materials, design or construction process is best suited for
local
conditions
Example of materials used in construction:
Cement
Soil
Steel
Paint
Reinforcing steel bar
Wood/timber
Concrete
Aggregates Asphalt
Galvanized iron sheet
Concrete
hollow blocks
nails
Bolts and nuts
Reinforced concrete
culvert pipes PVC pipes, etc.
CHAPTER 1: PROPERTIES OF MATERIALS
ENGINEERING MATERIALS
refer the materials carefully examine to meet the demands of
the structure
TEST
Searching for the result of materials
MANUFACTURING ENGINEERING
Is the study of techniques to turn bulk materials into
functional products and supplies
AUTOMATION
Is the common method in manufacturing with less labor
involved
PROPERTIES
Describe the performance criteria that involves structural
loading and bearing material
CLASSIFICATION OF PROPERTIES FOR ENGINEERING MATERIALS
1. Chemical Properties are associated with the transformation of the material into
another
a. Corrosion resistance
b. Acidity and alkalinity
2. Physical properties- no change in the composition of materials
a. Dimension
b. Density
c. Porosity
3. Mechanical Properties — measurement of materials' ability to carry or resist
mechanical force or stress
a. Strength
b. Stiffness
c. Hardness
4. Thermal —conductivity, specific heat expansion
5. Electric and magnetic — conductivity, magnetic. permeability, di-electric strength
6. Acoustical— sound, transmission, reflection
7. Optical — color, light transmission, light reflection
MECHANICAL PROPERTIES OF
1. HARDNESS
-Property of being hard and tough; engineering resistance to
penetration and resistance scratching
2. STRENGTH
-Resistance to the series of applications of load on the structure or
material without fracture
3. ELASTICITY -The property of regaining the original shape upon the removal of
external forces
4. DUCTILITY
-Property of material in which it may be plastically elongated
5. MALLEABILITY
-The property of a metal which enables to be hammered or bend
without breaking
6. DURABILITY -Is the measure of the period use of any structure or machine or
material
7. MACHINABILITY
-Resistance to different kinds of machine test
8. RESILIENCE -is a measure of the energy per unit volume that the material can
absorb without plastic deformation
9. STRAIN
-A unit of deformation to which material may be subjected to load
10.
TOUGHNESS
-The capacity of a material to absorb energy during plastic
deformation
11.
STIFFNESS
-It is a measure of the ability of a material to resist
deformation
12.
TYPES OF PLASTICITY
1. DISLOCATION is an imperfection in the crystal structure
Types of Dislocation
Positive edge dislocation
Negative edge dislocation — there are moved atoms in the other place below
the line
2. DEFORMATION spoil the natural form
Types of Deformation
Twinning — the process that results in the alteration of the other parts of
some crystal
Twinning plane — the plane that separates the part of different orientation
3. STRESS force that tends to deform or stretch
Types of Stress
Tension — to determine how a material will behave under the application of
tensile force
Compression — force that act so as to shorten the members carrying the load
Shear — these are attempted to move from one portion of the body with respect
to either surface
RELATIONSHIP OF STRESS AND STRAIN — use to compute the dividing load on the initial speed
of the specimen
STRESS RUPTURE
-A preliminary evaluation at elevated temperature; properties of
materials that maybe secured by means of stress rupture test
PROPORTIONAL LIMIT
-The maximum stress to which a material can be subjected at any
deviation from the proportionality of stress and strain
ELASTIC LIMIT
-The maximum stress to which a material may be subjected without
the occurrence of any stress remaining upon complete release of the load
YIELD POINT
-The process of yielding involves a discontinuous plastic deformation
of the gauge length
YIELD STRENGTH
-The stress of which the material exhibits a specified limiting
permanent set
ULTIMATE STRENGTH -Is the maximum unit stress that a material can withstand
13.
FATIGUE OR ENDURANCE LIMIT- is the maximum stress that can be sustained for a
specified number of a specifies without fracture
14.
CREEP- is a slow process of plastic deformation that takes place when a
material is subjected to a constant
conditioning load below its normal yield strength
Types of CREEP
1. Primary CreepThe period of initial deformation will be followed by a
period in which role of creep
gradually decreases
2. Secondary Creep- The creep rate may reach minimum deformation, will continue at a
uniform rate for a
period of designated time
3. Tertian/ Stage of CreepIf the temperature is high enough or stress is high
enough, the creep may then increase
markedly entering the tertiary stage of creep without leading to
eventual rupture of the specimen if that Is carried to completion
PROPERTIES OF ENGINEERING MATERIALS
1. STRENGTH —the ability to resist application of the load required during the service
of the structure
 Compression
 Shear
 Flexural
 Torsional
2. Resistance to elevated temperature
3. Fatigue resistance
4. Toughness
5. Corrosion resistance
CHARACTERISTICS FOR THE IDEAL MATERIAL TO BE SELECTED
1. Endless and rapid available source of supply
2. Cheap to refine and produce
3. Energy efficient
4. Strong and dimensionally fit at any temperature
5. Lightweight
6. Corrosion resistant
7. No harmful effects in the environment or people
8. biodegradable
9. numerous secondary uses
TWO (2) CLASSIFICATION OF MATERIALS
1. METALLIC
Types of metallic materials
a. Ferrous bearing (iron)
Steel
Cast iron
Wrought iron
b. Non-ferrous
copper
Zinc
tin
aluminum
magnesium
2. NON-METALLIC
Wood
Ceramics
Cement
Bricks
Rubbles
Rubber
Leather
plastic
CHARACTERISTICS OF NON-METALLIC MATERIALS
1. Maybe solid, liquid or gaseous
2. Usually brittle if solid
3. Usually, non-conductor
4. Usually dull if solid
CHARACTERISTICS OF METALLIC MATERIALS
1. Usually solid at ordinary temperature
2. Usually malleable and ductile at some degree
3. Usually good thermal and electrical conductor
4. It usually form an alloy
5. Lustrous as freshly cut surface
CLASSIFICATION AND GROUPING OF ENGINEERING MATERIALS
1. PURE METAL
Are those obtained when an ore is refined to yield a metallic
element
2. ALLOY
Is form when two or more relatively pure metals are melted
together to form a new
metal ex. steel
3. COATED METALS
Used for food container
4. CLAD METAL
Is use in the construction of oil storage tank where resistance
to corrosion cannot be
tolerated Inside the tank
TEST FOR MATERIALS
i.
CHEMICAL TEST
-It is used to detect the presence of an injurious amount of an undesirable
ingredient
-To detect the unevenness on the distribution of ingredients through a mass of
material
ii.
MECHANICAL TEST
-It is used to determine the quality of a material for construction including the
best of strength, ductility, brittleness, resistance to repeated stress and
hardness
DIFFERENT KINDS OF MECHANICAL TEST
1. Tension test
-Test used to determine how a material will behave under
the application of a tensile
force, it is also to determine the brittleness and ductility of a
material
2. Compression test -Used in determining the malleability or ductility of a material
3. Shear test
-Used to determine the shearing resistance and shearing strength
of the materials
4. Hardness
-Used to determine the hardness of a metal
COMMON HARDNESS TEST
a. BRITTLE TEST
the steel ball' 10mm in diameter Is pressed against the
plain finished surface of the
material to be tested with for soft materials
b. ROCKWELL TEST
Is a penetration test in which diamond cone is used for hard
materials and a hardened
steel 1/10 " in diameter for soft materials
c. SCLEROSCOPE TEST In this test, the height of rebound of a small type hammer is
measured after it has
dropped from a fixed height squarely upon the polished surface of
the test piece
d. MICROHARDNESS TEST Used to determine the hardness of a relative sheets of metal
e. MONOTRON TEST
The test is made by using an indentor which maybe hemispherically
diamond indentor
0.75 mm diameter
f. DIAMOND PYRAMID HARDNESS Is determined in much the same as the brittle test
MICROHARDNESS TESTERS
1. Microhardness testers
2. Rockwell superficial hardness tester
3. Tukon hardness tester
4. Knoop indentor
for TOUGHNESS
IMPACT TEST the toughness of material maybe indicated by the character of the
stress-strain relationship which is based upon the static test
KINDS OF LOADING
1. Dynamic loading
2. Rapid loading
EFFECTS OF HIGH TEMPERATURE ON PROPERTIES OF MATERIALS
1. The yield point become extremely low
2. Plastic deformation of structure would cause elastic deformation
3. Steel tubes would eventually result in a disastrous failure
PROPERTIES OF MATERIALS
OBJECTIVE.
To become acquainted with the important physical properties of materials.
DISCUSSION
Classification of Properties
Engineering Materials have a great number of properties. Most of the properties
will fall into one of the major classes listed below. Several examples each class
properties are included, but the listed lists are not complete.
PHYSICAL - dimensions, density, porosity
MECHANICAL - strength, stiffness. hardness
CHEMICAL s- corrosion resistance, acidity or alkalinity
THERMAL - conductivity, specific heat, expansion
ELECTRIC AND MAGNETIC -conductivity, magnetic permeability, di-electric strength
ACOUSTICAL - sound transmission, sound reflection
OPTICAL - color, light transmission, light reflection
Mechanical Properties
Material testing can include the determination of all these properties. However,
most of the testing work done in common materials testing laboratories is concerned with
mechanical properties. The primary features required of engineering materials at-e
related to their performance under load. Mechanical properties of materials are those
that have to do with behavior under applied forces Mechanical properties are expressed in
terms of quantities that are functions of stress or strain or both,
Strength
In general sense, strength refers to the assistance to failure of a structure, a
single piece of material, or a small part of it. Failure may be judge by excessive
deformation or by actual breaking of the part. Strength can refer to any of several types
of applied loads.
Tensile Strength - as a cable or chain
Compression strength - as a column
Shear strength - as of a rivet or hinge pin
Flexural strength - as of a beam supporting a floor
Impact Strength - any parts subject to shock loads
Stiffness has to do with the amount of deformation or deflection that occurs under load.
Elasticity refers to the ability of a material to deform under load without permanent set
when load is released. A spring
demonstrates this property.
Plasticity is the ability or a material to be permanently without breaking or cracking.
The metal in a cooking pan, or other
deep drawn exhibits good plasticity.
Ductility a different term for the property of plasticity but is applied to tensile
elongation characteristics, A ductile specimen Will stretch or elongate considerably
before breaking. A "brittle" material lack ductility.
Hardness is the resistance to indentation or abrasion of the surface material.
An understanding of the above properties IS fully dependent on understanding the
terms "load", "stress", "deformation", and "strain"; defining these properties is
possible only by use of these terms.
Load is the force applied to a specimen, structure or machine part. Loads are usually
given in Newton (kN) of weight of force. A column could have a load 5000 Newton on it.
The load could either a direct weight, or a force applied by testing machine.
Stress is the intensity of the internal forces that resist the load. Stress is measured
in force per unit area, commonly Newton er square meter or Pascal.
Deformation is the change in shape of a body, which result from some external force It
may be temporary or "elastic" deformation, or it may be "plastic" or permanent
deformation.
Strain is the change per' unit length of a body subject to stress.
Module 2:
Metals


Metals are opaque, lustrous elements that are good conductors of heat and
electricity.
Most metals are malleable and ductile and are, in general, denser than the other
elemental substances
“What are some applications of metals?”
Deformation of Metals
DEFORMATION
❑ changes in the dimensions and change in shape will take place.
❑ strain will be induced in the
material.
Excessive Elastic Deformation (EED)
❑ This type of deformation is temporary.
❑ influence of external load the material will undergo changes.
❑ magnitude of the load is increased the deformation becomes more and more
❑ maximum value corresponding to the yield point.
Excessive Plastic Deformation (EPD)
❑ This type of deformation is permanent in nature.
❑ Beyond the elastic zone.
❑ Influence of external load the material will undergo changes – and these changes are
permanent.
❑ Once the external load is removed the material will not recover its free state.
NECKING
❑ It cannot offer any resistance at all.
❑ Once necking is initiated the material fails at any moment.
❑ Fracture propagates faster even when the load is reduced.
❑ Separation occurs and the material breaks.
DISLOCATION MOVEMENT
❑ Occur when the atoms do not arrange themselves in a perfect regular repeating pattern
when the metal solidifies from the melt.
❑ Bonds between the atoms in the region near the dislocation core are distorted
❑These will break and re-form by a sufficiently high applied stress
❑ resulting in an apparent movement or slip of the dislocation by an amount called the
Burgers vector
DEFORMATION ZONE GEOMETRY
❑ For bringing about deformation in metals dies are used.
❑ Dies are flat or converging or conical shaped contours. Made of hard materials.
❑ The dies external forces or stresses are induced on to the metal or work piece to bring
about deformation.
❑ Basic features of the die is the ratio of the mean thickness(h) to the length(L) of
deformation zone.
❑ This is referred to as Deformation Zone Geometry Δ.
STRENGTHENING of METALS
In using the term ‘strengthening’, we are concerned with ways by which we can make
the start of slip more difficult.
GRAIN SIZE
• Clay
• Silt
• Sand
• Gravel
FORMULA:
σy = σ0 + kd^ (-1/2)
σy = Yield strength of our polycrystalline material
σo = Yield strength of one crystal on its own
k = proportionality constant
d = Grain size of the material
STRAIN HARDENING
In a tension test, a reasonably ductile metal becomes unstable and begins to form a neck
at strains of only about 30% or so.
ANNEALING
❑ New grains nucleate and grow, the material is restored to its original dislocation
density and the yield point returns to its original value.
❑ A useful way of controlling grain size
ALLOYING
One of the most powerful ways of impeding dislocation movement, and hence of increasing
the yield strength, is to add another element or elements to the metal in order to
distort the atomic lattice.
Dispersion Hardening
The alloying element or impurity combines with the parent metal.
The impurity is added to the molten metal at high temperature and then, as the alloy
cools and solidifies, the impurity– metal compound precipitates as small, hard, often
brittle, particles dispersed throughout the structure
EXAMPLE:
CuAl₂ formed after adding small quantities of copper to Aluminum or iron carbides formed
after adding small quantities of carbon to iron.
The effect of dispersion hardening on
dislocation movement (adapted from
Ashby and Jones, 2005).
QUENCHING AND TEMPERING
The quenching of steel is an example in
which an unstable microstructure is generated when there is no time for diffusion to keep
up with the requirements of thermodynamic equilibrium.
STRENGTHENING, DUCTILITY AND TOUGHNESS
Yield and Tensile strength
increase ductility,
toughness and fracture
toughness are reduced.
For example, continued cold
working will raise the yield strength ever closer to the tensile strength but at the same
time the reserve of ductility is progressively diminished and, in the limit, the material
will snap under heavy cold working.
FORMING of Metals
Forming There are many methods of
preparing metals and alloys for
use.
Before starting, we must recognize
that metallurgists look on these
not only as ways of shaping
materials but also as ways of
controlling their microstructure
and, consequently, their
properties.
CASTINGS
Most common metals can be produced by casting
into moulds.
The cast may be of the shape and dimensions
required for the component, or a prism of
material may be produced for further processing.
HOT WORKING
The working of metals and alloys by
rolling, forging, extrusion etc. depends upon
plasticity, which is usually much greater at high
temperatures, i.e. temperatures above the metals’
recrystallization temperature.
This allows all the common metals to be heavily deformed, especially in compression
without breaking
One disadvantage of hot forming arises from the contraction of the article on
cooling and from such problems as oxidation. These and other factors conspire to limit
the precision of the product. In some cases the tolerances are acceptable, but to meet
more demanding tolerances further cold forming or machining is required.
Hot working PROCESS
1. Rolling
2. Forging
3. Extrusion
4. Drawing
Rolling is a metalworking process that occurs above the recrystallization temperature of
the material. After the grains deform during processing, they recrystallize, which
maintains an equiaxed microstructure and prevents the metal from work hardening.
Forging can be defined as “a metal shaping process in which a malleable metal part, known
as a billet or workpiece, is worked to a predetermined shape by one or more processes
such as hammering, upsetting, pressing and so forth where the workpiece is heated up to
about 75% of its melting temperature”.
Extrusion is a hot working process, which means it is done above the material's
recrystallization temperature to keep the material from work hardening and to make it
easier to push the material through the die.
Drawing is a metalworking process which uses tensile forces to stretch metal or glass. As
the metal is drawn,
it stretches thinner, into a desired shape and thickness.
COLD WORKING Because of their ductility at room temperature many metals and alloys can be
cold worked, that is to say, shaped at temperatures below their recrystallization
temperature. This creates an immense number of dislocations and, as a con-sequence, the
metal work-hardens and its yield point is raised. Indeed, for pure metals and some alloys
it is the only way of increasing the yield strength.
Cold working PROCESS
1. Rolling – extensively used to produce sheet material
2. High-strength wire – as used for pre-stressing strands and cables, is cold drawn by
pulling through a tapered die.
JOINING The design and fabrication of joints between metallic structural components are
obviously crucial factors in ensuring the success of the structure.
Design engineers have Codes of Practice to help them in their task, but some understating
of the processes involved and relevant materials’ behavior is also important.
Common methods of Joining:
1. Welding
2. Brazing, Soldering,
and Gluing
3. Bolting and Riveting
WELDING All welding involves essentially the same sequence of operations at the joint.
The material is heated locally to its melting temperature, additional metal may or
may not be added and the joint is then allowed to cool naturally.
Some protection to the weld to avoid oxidation of the metal when molten and during
cooling is often provided by a slag layer (which is knocked-off when the weld has cooled)
or by working in an atmosphere of an inert gas such as argon.
Note: Whatever the material or process all welds should comply with the two following
ideal requirements:
1. There should be complete continuity between the parts to be joined, and every part of
the joint should be indistinguishable from the parent metal. In practice this is not
always achieved, although welds giving satisfactory performance can be made.
2. Any additional joining metal should have metallurgical properties that are no worse
than those of the parent metal. This is largely the concern of the supplier of welding
consumables, though poor welding practice can significantly affect the final product.
BRAZING, SOLDERING, AND GLUING
Brazing and soldering, and in some cases gluing, involve e joining by means of a thin
film of a material that has a melting temperature lower than that of the parent material
and which, when melted, flows into the joint, often by capillary action, to form a thin
film which subsequently solidifies.
BOL TING AND RIVETING
Bolting and riveting are by far the most common ways of making joints in such
circumstances.
Both rely on friction. A tightened bolt forces the two members together and the friction
between nut and bolt at the threads holds it in place.
OXIDATION AND CORROSION
OXIDATION
Is an electrochemical breakdown of the metal. Oxygen leads to oxidation.
CORROSION an electrochemical reaction that involves changes in both the metal and the
environment in contact with the metal.
Difference Between Oxidation and Corrosion
The only distinction between the two processes is what caused it to occur.
Corrosion is brought on by wet weather conditions (destruction of metals as a result of
rain, sleet, snow, etc.) whereas oxidation occurs when naturally air reacts with metals.
DRY CORROSION
Occurs when oxygen in the air reacts with metal without the presence of a liquid
WET CORROSION
Occur through electron transfer, involving two processes, oxidation and reduction
TYPES OF CORROSION
UNIFORM CORROSION Refers to the corrosion that proceeds at approximately the same rate
over the exposed metal surface
LOCALIZED CORROSION The selective removal of metal by corrosion at small area or zones on
a metal surface.
TYPES OF LOCALIZED CORROSION
PITTING CORROSION One of the most destructive types of corrosion, as it can be hard to
predict, detect and characterized
CREVICE CORROSION Often associated with a stagnant micro-environment, like those found
under gasket, washers and clamps
STRESS CORROSION CRACKING A result of the combination of tensile stress and a corrosive
environment, often at elevated temperatures.
INTERGRANULAR CORROSION Localized attack along the grain boundaries, while the bulk of
the grains remain largely unaffected
CORROSION PREVENTION
❑ Protective coating
❑ Metal type
❑ Design modification
IRON and STEEL
IRON- is an incredibly useful substance. It's less brittle than stone yet, compared to
wood or copper, extremely strong. Ferrous (iron-based) metals have widespread use
throughout all branches of engineering but are particularly important in construction.
TYPES OF IRON
1. Pig iron
2. Cast Iron
3. Wrought Iron
Pig Iron – crude iron as first obtained from a smelting furnace, in the form of oblong
blocks.
Cast Iron - a hard, relatively brittle alloy o iron and carbon that can be readily cast
in a mold and contains a higher proportion of carbon than steel.
Wrought Iron - a tough malleable form of iron suitable for forging or rolling rather than
casting, obtained by puddling pig iron while molten. It is nearly pure but contains some
slag in the form of filaments.
Steel - Steel is made by mixing iron and carbon to make an alloy. Steel is much stronger,
much harder and much less brittle than iron. This is because the carbon atoms, within the
iron lattice, pins down the dislocations, so that layers of iron atoms cannot slide over
each other. This is why steel has many more uses than iron.
Steel is much harder than iron, and doesn’t become blunt so easily.
So, swords, daggers and knives, as well as shields, are typically made from steel.
A steel blade can easily cut an iron sword in two. Arrow heads and spear heads are also
made from steel. They are much harder, tougher and sharper than similar pieces made from
iron, brass or bone.
TYPES OF STEEL
Carbon Steel -Carbon steel is dull and matte in appearance and is vulnerable to
corrosion. Carbon steel can contain other alloys, such as manganese, silicon, and copper.
There are three main types of carbon steel: low carbon steel, medium carbon steel, and
high carbon steel.
Alloy Steel - Alloy steels are a mixture of several metals, including nickel, copper, and
aluminum. It tends to be cheaper and are used in mechanical work. The strength and
property of alloy steels depends on the concentration of elements they contain.
Stainless Steel - Stainless steels are shiny, corrosion resistant, and used in many
products. It is strong and can withstand high temperatures. It’s an extremely versatile
material that is customizable depending on your purpose.
Tool steels - are hard and heat and scrape-resistant.
They are named tool steels because they are often used to make metal tools, such as
stamping, cutting, and mold-making tools.
They are also commonly used to make hammers.
Uses of Steel
*Steel is environment-friendly & sustainable. It possesses great durability.
• Compared to other materials, steel requires a low amount of energy to produce
lightweight steel construction.
• Steel is the world’s most recycled material which can be recycled very easily. Its
unique magnetic properties make it an easy material to recover from stream to be
recycled.
• Steel can be designed into various forms. It gives better shape and edge than iron
which is used to make weapons.
• Engineering steels are used for general engineering and manufacturing sectors.
• Steel is highly used in the automobile industry. Different types of steels are used in
a car body, doors, engine, suspension, and interior. The average 50% of a car is made of
steel.
• Steel reduces CO2 emissions.
• All types of energy sectors demand steel for infrastructure and resource extraction.
• Stainless steels are used to produce offshore platforms and pipelines.
• Steels are used for packaging and protecting goods from water, air and light exposure.
*Most of the household appliances like fridge, TV, oven, sinks, etc. are made of steel.
• Steels are used for producing industrial goodies like farm vehicles and machines.
• Stainless steel is used as a cutlery material.
• Because of its easily welding capability and attractive finishing, steel has become a
prominent feature in modern architecture.
•Stainless steel gives a hygienic environment. That’s why it is used for surgical
implants.
•Steel has a wider range of temperature which is used to make large sheets.
•Renewable energy resources like solar, hydro and wind power use the stainless-steel
components.
•Mild steel is used for building construction. It is also a highly favored building frame
material.
DISADVANTAGES OF STEEL:
1.Maintenance cost of a steel structure is very high. Due to action of rust in steel,
expensive paints are required to renew time to time. So that resistance against severe
conditions increases.
2.Steel has very small resistance against fire as compared to concrete. Almost from 600700C half of steel strength reduced.
3. Steel cannot be mold in any direction you want. It can only be used in forms in which
sections originally
exists.
4. If steel loses its ductility property, then chances of brittle fractures increase.
5. If there are very large variations in tensile strength than this lead steel to more
tension. Due to which steel tensile properties graph falls down.
STEEL VS. WOOD
• Steel structures provide long-term, consistent performance.
• Steel is a noncombustible material and will not contribute to the spread of a fire.
• Steel framing improves design efficiency, saves time, and reduces costs.
• Steel structures perform well during earthquakes and other extreme events
• Steel framing provides environmental benefits and complies with sustainable building
standards.
ALUMINUM
The use of aluminum in construction is second only to that of steel. In comparison with
structural steel, aluminum alloys are lightweight, resistant to weathering and have a
lower elastic modulus, but can be produced with similar strength grades. They are easily
formed into appropriate sections and can have a variety of finishes.
Aluminum has properties which makes it suitable as a building / construction material.
Nowadays in advanced countries, aluminum became the important construction material for
buildings especially for industrial buildings along with brick, cement and steel.
Properties of Aluminum as Building Material
❑ Air tightness
❑ High strength to weight ratio
❑ Ease in fabrication and assembly
❑ Cryogenics
❑ Low Handling and transportation cost
❑ High reflectivity
❑ Corrosion resistance
❑ Appearance
❑ High Scrap value
❑ Sound proof
❑ Maintenance
Air Tightness
Doors and windows or its frames made from aluminum are perfectly air tight which cannot
permit dust or air or water when they are closed.
Nowadays for fully air-conditioned buildings like seminar rooms, theaters etc. aluminum
doors and windows are using
Strength to Weight Ratio
It represents that small amount of aluminum can give more strength to structure. Because
of less weight we can construct the structure in less time and load transferring to
foundation also reduces.
Ease in Fabrication and Assembly
Compared to other metals aluminum alloys can be cast, forged, extruded, rolled or welded
easily.
During or after composition of aluminum alloy it cannot break because it is not having
brittle nature. The assembly of aluminum structures can be easily dismantled or
transported or assembled.
Cryogenics
Study of phenomena occur at very low temperature. At very low temperature steel becomes
brittle and lost its strength. But in the case of aluminum, it is highly suitable for
sub-zero temperatures. So, for snow bound areas aluminum structures are highly
preferable.
Low Handling and Transportation Cost
Handling of aluminum is very easy because of its less weight.
So, we can transport it easily in large quantity to any place with low transportation
cost.
Reflectivity
Reflectivity of aluminum is also very high. Aluminum does not absorb radiant heat and low
absorption heat.
So, during summer it maintains the interior cooler and during winter maintains warmer
conditions.
Corrosion Resistance
Corrosion resistance of aluminum is very high. It is not affected by weathering
conditions.
They can withstand against humid or hot dry conditions very well.
Because of its good corrosion resistance, aluminum corrugated sheets are widely used for
power plants, chemical plants, paper mills, petroleum refineries etc.
Appearance
Aluminum also gives beauty to the structure. Smooth and bright finishing is possible for
aluminum structures. We can also provide various shades of colors on the aluminum sheets
to enhance decorative style.
CONCRETE
Concrete - a composition material that consist of essentially of binding medium which are
embedded particles or fragments of aggregates in hydraulic cement concrete.
Fundamentals of Concrete
l. Aggregates- composed of sand and gravel or crushed stone.
2. Paste- comprises of Portland cement and water that binds the aggregates.
Composition of Paste are:
1. Portland Cement
2. Water
3. Entrapped Air
Quality of Concrete- it depends to a great extent upon the quality of the paste. In
proper made concrete, each particle of aggregates is completely coated with paste and all
the spaces between aggregate particles are completely filled with paste.
For a given materials and condition of curing, the quality of the hardened concrete is
determined by the amount of water used in relation to the amount of cement.
Some advantages of reducing water content are:
1.
2.
3.
4.
5.
6.
7.
increase in compressive and flexural strength
Increase in water tightness
Lower absorption
Resistance to weathering
Better bond between successive layer
Better bond between concrete from wetting and drying
Less volume changes

The less water used, the better the quality of concrete provided that can be
compacted properly,
Five (5) Basic Components of Concrete are:
1. Cement
2. Water
3. Air
4. Fine aggregates (sand)
5. Coarse aggregates
Engineering Properties of Concrete



Setting and hardening
Strength
Dimension stability
Physical Condition of Concrete
*Concrete must continue to hold enough moisture throughout the curing period in order
for the Portland cement to hydrate.
• Freshly cast concrete has abundance of water, but as drying progresses from the surface
inward, strength gain will cease at each depth as the relative humidity there drops below
80%.
• When concrete dries, it shrinks just as wood, proper and clay. Drying shrinkage is a
primary cause of cracking and the width of cracks is a function of the degree of drying.
• Hardened concrete- also relate to its moisture content, the included elasticity, creep,
fire resistance, abrasion resistance and durability.
Properties of Concrete
1. Water tightness- when concrete is exposed to weather or other severe exposure
condition, it should be watertight. Test shows that water tightness of paste
depends primarily on the ratio of mixing water to cement and the length of the
moist-curing period.
2. Abrasion resistance- concrete must have a high abrasion resistance, strong
concrete resists abrasion more than a weak concrete.
3. Durability (volume stability)- hardened concrete changes volume slightly due in
change of temperature, moisture content and sustained stress. The volume or the
length changes may be range from about 0.01% to 0.08%. Thermal volume changes of
hardened concrete are approximately the same as those for steel.
SEVERAL FACTORS OF SHRINKAGE
l. Amount of mixing water and aggregates
2. Properties of aggregates
3. Size of specimen
4. Relative humidity and temperature
5. Method of curing
6. Degree of hydration
7. Time
Special Types of Concrete
1. Structural Lightweight Concrete- is concrete made of light weight aggregates that have
a density in the range of 90 to 1 15 #s/cubic foot (1140 to 1850 kg/m3).
-Due to its lower aggregate density, lightweight concrete does not slump as much as
normal weight concrete that has the same workability.
2. Lightweight Insulating Concrete- are used principally for roofs, firewalls,
floodwalls, floor wills and underground thermal conduits lining.
3. Heavy Weight Concrete- are produced with special heavy aggregates and have densities
of up to 400#s/ft3 (6400 kg/m3).
-Is used principally for radiation shielding but is also used for counterweight and other
applications where high density is important. As shielding material, heavyweight concrete
protect against the harmful effects of x-rays, gamma rays and neutron radiation.
4. White concrete- is used to produce white concrete.
-Is made with aggregates and water that contain no material that discolour the concrete.
5. Colored Concrete- can be produced by using colored aggregate or by adding color
pigments or both.
*High-performance concrete- is a relatively new term used to describe concrete that
conforms to a set of standards above those of the most common applications, but not
limited to strength. While all high strength concrete is also high-performance, not
all high-performance concrete is high-strength.
*Roller-compacted concrete- sometimes called rollcrete, is a low-cement-content
stiff concrete placed using techniques borrowed from earthmoving and paving work.
The concrete is placed on the surface to be covered, and is compacted in place
using large heavy rollers typically used in earthwork. The concrete mix achieves a
high density and cures over time into a strong monolithic block.
• Glass concrete- Recent research findings have shown that concrete made with
recycled glass aggregates have shown better long term strength and better thermal
insulation due to its better thermal properties of the glass aggregates.
*Polymer concrete- is concrete which uses polymers to bind the aggregate. Polymer
concrete can gain a lot of strength in a short amount of time. For example, a
polymer mix may reach 5000 psi in only four hours. Polymer concrete is generally
more expensive than conventional concretes.
Composition of Concrete
• Cement
Portland cement is the most common type of cement in general usage. It is a basic
ingredient of concrete, mortar, and plaster.
• Water

Combining water with a cementitious material forms a cement paste by the
process of hydration. The cement paste glues the aggregate together, fills voids
within it, and allows it to flow more freely. Less water in the cement paste will
yield a stronger, more durable concrete; more water will give an freer-flowing
concrete with a higher slump

Impure water used to make concrete can cause problems when setting or in
causing premature failure of the structure.

Hydration involves many different reactions, often occurring at the same
time. As the reactions proceed, the products of the cement hydration process
gradually bond together the individual sand and gravel particles, and other
components of the concrete, to form a solid mass.
Aggregates
Fine and coarse aggregates make up the bulk of a concrete mixture. Sand, natural
gravel and crushed stone are mainly used for this purpose. Recycled aggregates
(from construction, demolition and excavation waste) are increasingly used as
partial replacements of natural aggregates, while a number of manufactured
aggregates, including air-cooled blast furnace slag and bottom ash are also
permitted.
6. No-Slump Concrete- refers to concrete with a consistency corresponding to a slump of I
in. (25mm.) or less It is used in the precasting industry for fabrication of pipes,
hollow- core slabs, railroad ties, concrete blocks and concrete bricks.
Types of Concrete and their Weight
l. Lightweight Concrete
-Is classified into 3 types depending upon the kind of aggregates used which
predetermines their weight.
 Low Density Concrete
-For insulation purposes with the unit weight rarely exceeding 50 pounds/ft3
or 80kg/m3
 Moderate-Strength Concrete
-has a unit weight from 360 to 960 kg/m with a compressive strength of 70 to
120 kg/m3 and is usually used to fill over light gauge steel floor panels.
 Structural Concrete
-Somewhat the same characteristics with that of medium stone concrete and
weighs from 90 to 120 #s/ft3 or 1440 to 1920 kg/m3
2. Medium Stone Concrete
Is also known as structural concrete weighing from 145 to 154 #s/ft3 generally assumed to
be 1 50 #s/ft3 or 330 kg/m3.
3. Heavy Weight Concrete
-Is used as a shield against gamma rays and other similar structure. It is also used as
counterweight for a lift bridge. The contents of heavy weight concrete are cement, heavy
iron ores, crushed rock, steel craps, punching or fine shot aggregates.
Proportioning of Concrete Mixture
The right proportioning of the ingredients of concrete provides as balance between the
requirements of:





Economy
Workability
Strength
Durability
Appearance
Two Methods Adopted in Proportioning
Concrete Mixtures
1. By volume, 1:2:4 (one part cement, two parts aggregates and four parts coarse
aggregates)
2. By weight measure
Various Tests Conducted for concrete are:
1. Slump Test- this method requires a fabricated metal.
2. Compressive Test- is the process applied in determining the strength of concrete.
Three (3) Basic Types of Joints Used in Concrete Construction
1. Control Joints
-Are the most effective method of preventing unsightly cracking.
-Are grooved, scoud, or sawed in sidewalks, driveways, pavements and floors so that any
cracking will occur in this joints.
-Permit horizontal movement in the plane of the slab; they are cut to a depth of
approximately one quarter the slab thickness or a minimum of one-fifth the thickness.
2. Isolation Joints
-Separate a slab from other parts of a structure and permit horizontal and vertical
movement of the slab. They are placed at the junction of floor with walls, columns,
footing and other joints where restraint can occur. They extend the full depth of the
slab and include a pre molded joint filler.
3. Construction Joint
-Occur where concreting work is included for the day; they separate areas of concrete at
different times.
Workability
The case of placing and consolidating freshly made concrete
Workability can also describe as:
I. Consistency Is the degree of wetness or slump of a concrete mix It varies directly
with the amount of water in the mix,
2. Plasticity Is the fresh concrete can be molded or deformed without segregation
3. Mobility Is the capacity of the concrete for movement of flow particularly during
vibration
Workability of Concrete
Concrete is said to be workable under the following considerable.
l. Proportioned for transport and placed without segregation The aggregate particles must
be uniformly distributed.
2. Easily molded into desired shapes and completely fill the space it is to occupy.
3. Easily finished
Concrete should be proportional to produce workability required for a particular
structure, For example, a fairly thick or stiff concrete mixture may be used for pavement
because the concrete can be vibrated and tempered
Concrete for thin wall and a small column structure may be compacted with a minimum
vibration. A semi-fluid mixture is required for concrete in applications where it must
now in order to fill all the space it is to occupy.
Durability of Concrete
Durability- is the ability to resist the forces of deterioration.
The forces that cause deterioration are:




Freezing the thawing water saturated concrete
Expansion caused by the reaction between reactive aggregates and alkali cement
Reaction between soil and water sulphate and the hydrated Portland cement.
Expansion and shrinkage caused by wetting and drying
Things to avoid in placing concrete to its final form.




Segregation of particles
Displacement of forms
Displacement of reinforcement in the form
Poor bond between successive layers of concrete.
Factors that regulate the strength of concrete





Correct Proportion
Suitable or quality of the materials
Proper methods of mixing
Proper placement or depositing of concrete inside the forms
Adequate protection of concrete during the period of curing
Curing of Concrete
The protection of concrete from loss of surface moisture is 7 days when ordinary Portland
cement is used and 3 days for an early high strength Portland cement:
The methods applied in curing surface concrete are:





Covering of the surface with burlap continuously wet for the required period
Covering of the slab with a layer of wet sand or saw dust I in. or 25mm. thick
Wet straw or layer on top of the slab continuously wet
Continuously sprinkling of water on the slab surface.
Avoid early removal of forms. This well permit under evaporation of moisture in the
concrete.
The objectives of curing are:
 To prevent (or replenish) the loss of moisture.
 To control the concrete temperature for a definite time.
Curing- has a strong influence on properties of hardened concrete such as durability,
strength, water-thickness, wear resistance, volume stability and resistance to freezing
and thawing.
With proper curing, the concrete will become stronger and more resistant to stress,
abrasion and frost. The improvement is rapid at early ages but continuous more slowly for
an indefinite period.
Shrinkage- to contract due to cold or heat.
Concrete keep continually moist will expand slightly, when permitted to dry
concrete will shrink. Concrete under stress will deform elastically. Sustained stress
will result in additive deformation called creep.
Two Basic Causes of Crack in Concrete are:
• Stress due to applied loads
• Stress due to drying shrinkage or temperature change
Concrete shrinkage cracks occur because of restrain. When shrinkage occurs and
there is no restrain, the concrete does not crack.
Thermal Stress- due to fluctuation in temperature can cause cracking.
Restrains come from several sources
 Drying shrinkage is always greater near the surface of the concrete so the moist
inner portions restrain.
 Other sources of the restrain are reinforcing steel embedded in concrete
 The interconnected parts of the concrete structure
 The friction of the sub grade on which a concrete slab or wall is placed
Mixing Concrete:
2 Ways in Mixing Concrete:
1. Site job mixing — shall be done in a batch mixer or approved type. The mixer shall be
rotated at speed recommended type. The mixer shall be rotated at speed recommended by the
manufacturer and mixing shall be continued for at least 1 1/2 minimum.
2. Ready mixed concrete — quantity for numerous special purposes can be ordered directly
from the ready mix concrete producer. The desired type and quality of concrete is
delivered in the project site very rapidly. The production of various concrete mixes is
programmed by an electric computer and batches of concrete for any desired sizes are
proportioned automatically by electric control. All ingredients are measured by weight.
A ready-mix concrete is mixed either:
 Mobile Mixer— a batch of concrete is place in a mobile mixer at the plant. The
mixing take place from the time mixer leaves the plant until it reaches the job
site.
 Stationary Mixer — the concrete is mixed before it is placed in the truck mixer,
where the concrete is only agitated.
 Hand mixing — a good concrete can be produced by hand mixing.
Admixture of Concrete
Admixture — are those ingredients in concrete other than Portland cements, water and
aggregates that are added to the mixture before and during mixing.
Classification of Admixture by Function:
1. Air-entraining admixture — are used to entrain microscopic air bubbles. Ex. Alkyl
benzene sulphate, polyethylene oxideoxide, detergents or salts of salty acid.
2. Reducing admixture — used to reduce the quality of mixing water required to produce
concrete of a given consistency or increases the slump of the concrete for given water
content. Water reducing admixture also reduced the setting time of concrete.
3. Retarding admixture — used to retard the rate of setting of concrete. Retarders do not
decrease the initial temperature of concrete.
Uses of Retarders in Concrete
• Offset the accelerating affect the hot weather on the setting of concrete.
• Delay the initial set of concrete or grout when difficult or unusual condition
placement occur, such as placing concrete in large pieces and foundations. Cementing oil
well or pumping grout.
• It also acts as water reducing
*It may also entrain some air in concrete.
4. Accelerating admixture — is used to accelerate strength development of concrete at
early age.
The common accelerators cause an increase in the drying shrinkage of concrete. The
strength development of concrete can be accelerated by:
 Using type Ill high-early-strength Portland Cement
 Lowering the water cement ratio by increasing the cement content
 Curing at higher temperature.
calcium Chloride - is the active materials or most commonly used as an accelerating
admixture.
5. Pozzolans — a siliceous and aluminous material.
Uses of Pozzolans:




Sometimes use in concrete to help reduce external temperature
To reduce or eliminate potential expansion from the alkali reactive aggregate
To counter expansion
To improve the sulphate resistance of concrete
6. Workability agent — is entrained air. It acts as a lubricant and is especially
effective in
proving the workability of mixture.
Different types of agents:
 Bonding admixtures — are usually water emulsion of several organic materials
including rubber, polyvinyl chloride, polyvinyl acetate, acrylics, and butadiene.
 -Non-re-emulsifiable types are resistant to water, better suited to exterior
application and used in place where moisture is present.
 Grouting agents- are used in a variety of purposes, to stabilize foundation, full
crack and joints in concrete work, cement oil wells, fill core of masonry walls,
grout tendons and anchors, bolts and prep laced aggregate. To alter the properties
of grout for specific application, various air-entraining admixtures, accelerating,
retarders and workability agents are often used.
 Damp Proofing and Permeability Reducing agents — include in certain soaps,
stearates and petroleum products. They may reduce the permeability of concrete that
are low cement content, high water, cement ratio. Sometimes use to reduce the
transmission of moisture through concrete that is in contact with soap or damp
earth.
 Gas-forming agent — aluminium powder and other gas-forming materials are sometimes
added to concrete and grout in very small quantity to cause a slight expansion
prior to hardening.
Cement




is powder and is one of the main ingredients in concrete
cement and concrete have been used in construction since at least the Roman Empire
modern cement is made of limestone, silicon, calcium, and often aluminum and iron
the type of cement used in almost all concrete is Portland cement. Portland cement
has been around since 1824. The name Portland does not refer to a brand name, as
many might think. The original inventor, Joseph Aspdin, was a British bricklayer
and named his new invention "Portland" because its color reminded him of the color
of the natural limestone on the Isle of Portland which is a peninsula in the
English Channel
Type of Cement
1. Portland cement- is a particular type of hydraulic cement. Portland cement contains
hydraulic calcium silicates. There are eight specific types of Portland cement that
fall into categories ranging from Type I to Type V.
• Type I and Type IA are general purpose cements. Type Il and Type IIA contain tricalcium
aluminate, but no more than 8%. To compare to the hydraulic cement types, some of the
Type Il cements meeting the standard for the moderate heat of hydration type.
• Type Ill and Type IllA are similar to Type I cements. However, they have higher early
strengths because they are ground finer. Type IV cements are used in special types of
structures that require a small amount of heat to be generated from hydration. Type IV
cements develop their strength over a longer period of time when compared to other types.
Finally, Type V cement has a high sulfate resistance which means it contains no more than
5% tricalcium aluminate.
Type
Name
Purpose
I
Normal
General-purpose cement suitable for most
purposes.
IA
Normal-Air Entraining
An air-entraining modification of Type l.
II
Moderate Sulfate Resistance
Used as a precaution against moderate sulfate
attack. It will usually generate less heat at a
slower rate than Type I cement.
IIA
Moderate Sulfate ResistanceAir Entraining
An air-entraining modification of Type ll.
III
High Early Strength
Used when high early strength is needed. It is
has more CJS than Type I cement and has been
ground finer to provide a higher surface-tovolume ratio, both Of which speed hydration.
Strength gain is double that of Type I cement in
the first 24 hours.
IIIA
High Early Strength-Air
Entraining
An air-entraining modification of Type Ill.
IV
Low Heat of Hydration
Used when hydration heat must be minimized in
large volume applications such as gravity dams.
Contains about half the C3S and CYA and double
the CS of Type I Cement.
V
High Sulfate Resistance
Used as a precaution against severe sulfate
action - principally where soils Or groundwaters
have a high sulfate content. It gains strength
at a slower rate than Type I cement. High
sulfate resistance is attributable to low C3A
content.
Blended Cement- is also hydraulic cement and is made by mixing two or more materials.
Usually, the primary materials used in blended cement are Portland cement and slag
cement. Fly ash, silica fume, calcined clay, pozzolan, and hydrated lime are also used.
There are two main types of blended cement:
Type IS (X): Portland blast furnace slag cement
Type IP (X): Portland-pozzolan cement
The X represents the amount of the second material that is in the mixture.
Physical Properties of Portland Cement
 Fineness - or particle size of Portland cement affects hydration rate and thus the
rate of strength gain. The smaller the particle size, the greater the surface areato-volume ratio, and thus, the more area available for water-cement interaction per
unit volume. The effects of greater fineness on strength are generally seen during
the first seven days (PCA, 1988).
 Soundness - When referring to Portland cement, "soundness" refers to the ability of
a hardened cement paste to retain its volume after setting without delayed
destructive expansion (PCA, 1988). This destructive expansion is caused by
excessive amounts of free lime (CaO) or magnesia (MgO). Most Portland cement
specifications limit magnesia content and expansion. The typical expansion test
places a small sample of cement paste into an autoclave (a high pressure steam
vessel). The autoclave is slowly brought to 2.03 MPa (295 psi) then kept at that
pressure for 3 hours. The autoclave is then slowly brought back to room temperature
and atmospheric pressure. The change in specimen length due to its time in the
autoclave is measured and reported as a percentage. ASTM C 150, Standard
Specification for Portland Cement specifies a maximum autoclave expansion of 0.80
percent for all Portland cement types
Setting Time cement paste setting time is affected by a number of items including: cement
fineness, water-cement ratio, chemical content (especially gypsum content) and
admixtures. Setting tests are used to characterize how a particular cement paste sets.
For construction purposes, the initial set must not be too soon and the final set must
not be too late. Additionally, setting times can give some indication of whether or not a
cement is undergoing normal hydration (PCA, 1988).
• Strength - cement paste strength is typically defined in three ways: compressive,
tensile and flexural. These strengths can be affected by a number of items including:
water- cement ratio, cement-fine aggregate ratio, type and grading of fine aggregate,
manner of mixing and molding specimens, curing conditions, size and shape of specimen,
moisture content at time of test, loading conditions and age. Since cement gains strength
over time, the time at which astrength test is to be conducted must be specified.
Typically times are 1 day (for high early strength cement), 3 days, 7 days, 28 days and
90 days (for low heat of hydration cement).
• Specific Gravity Test- is normally used in mixture proportioning calculations, The
specific gravity of Portland cement is generally around 3.15 while the specific gravity
of Portland-blast-furnace-slag and Portland- pozzolan cements may have specific gravities
near 2.90 (PCA, 1988).
• Heat of Hydration- is the heat generated when water and Portland cement react. Heat of
hydration is most influenced by the proportion of C3S and C3A in the cement, but is also
influenced by water-cement ratio, fineness and curing temperature. As each one of these
factors is increased, heat of hydration increases. In large mass concrete structures such
as gravity dams, hydration heat is produced significantly faster than it can be
dissipated (especially in the center of large concrete masses), which can create high
temperatures in the center of these large concrete masses that, in turn, may cause
undesirable stresses as the concrete cools to ambient temperature.
2. Non-Portland hydraulic cements
o
o
Pozzolan-lime cements- mixtures of ground pozzolan and lime are the cements
used by the Romans, and can be found in Roman structures still standing (e.g.
the Pantheon in Rome). They develop strength slowly, but their ultimate
strength can be very high. The hydration products that produce strength are
essentially the same as those produced by Portland cement.
Slag-lime cements- ground granulated blast furnace slag is not hydraulic on
its own, but is "activated" by addition of alkalis, most economically using
lime. They are similar to pozzolan lime cements in their properties. Only
o
o
o
o
granulated slag (i.e. water-quenched, glassy slag) is effective as a cement
component.
Super sulfated cements- these contain about 80% ground granulated blast
furnace slag, 15 % gypsum or anhydrite and a little Portland clinker or lime
as an activator. They produce strength by formation of ettringite, with
strength growth similar to a slow Portland cement. They exhibit good
resistance to aggressive agents, including sulfate.
Calcium aluminate cements- are hydraulic cements made primarily from
limestone and bauxite. The active ingredients are monocalcium aluminate
CaA1204 (CaO • A1203 or CA in Cement chemist notation, CCN) and mayenite
Ca12A114033 (12 CaO • 7 A1203 , or C12A7 in CCN). Strength forms by hydration
to calcium aluminate hydrates. They are well-adapted for use in refractory
(high-temperature resistant) concretes, e.g for furnace
Calcium sulfoaluminate cements -are made from clinkers that include
ye'elimite or S in Cement chemist's notation) as a primary phase. They are
used in expansive cements, in ultra-high early strength cements, and in "lowenergy" cements. Hydration produces ettringite, and specialized physical
properties (such as expansion or rapid reaction) are obtained by adjustment
of the availability of calcium and sulfate ions. Their use as a low-energy
alternative to Portland cement has been pioneered in China, where several
million tons per year are produced. Energy requirements are lower because of
the lower kiln temperatures required for reaction, and the lower amount of
limestone in the mix. In addition, the lower limestone content and lower fuel
consumption leads to a C02 emission around half that associated with Portland
clinker. However, S02 emissions are usually significantly higher.
Natural cements- correspond to certain cements of the pre-Portland era,
produced by burning argillaceous limestones at moderate temperatures. The
level of clay components in the limestone (around 30-35 %) is such that large
amounts of belite (the low-early strength, high-late strength mineral in
Portland cement) are formed without the formation of excessive amounts of
free lime. As with any natural material, such cements have highly variable
properties.
Special Cements
o
o
o
o
White Portland Cement- is similar in all respects to normal Portland except in
color. It is made from specially selected raw materials containing negligible
amounts of iron and manganese oxide, and the manufacturing process is controlled to
produce a pure white, non staining cement. It is used primarily for architectural
purposes such as curtain-wall and facing panels, decorative concrete, stucco, tile
grout or wherever white or colored concrete or mortar is specified.
Masonry Cement- has been specially designed to produce better mortar than that made
with normal Portland Cement or with a lime-cement combination. It is made by
grinding together a carefully proportioned mixture of normal Portland cement
clinker and high- calcium limestone.
Air-Entraining Portland Cement- sometimes small amount of certain air-entraining
agents are added to the clinker and ground with to produce air-entraining cements.
Concrete made with them contains millions of minute well-distributed and completely
separated air bubbles. It has proved to be more resistant to severe frost and to
the effects of salt applied to sidewalks and pavements for ice and snow removal.
Oil- Well Cement — this is a special Portland Cement used for sealing oils wells.
It must be slow- setting and resistant to high temperatures and pressures. There
are specifications for oil-well cements (API Standard IOA) which cover requirements
for six classes of cement, each applicable for use at a certain range of depths.
o
Waterproofed Portland Cement- is normally produced by adding a small amount of a
stearate, usually calcium or aluminum, the cement clinker during the final
grinding. It is made in both white and gray color.
Uses of Cement


Strengthened with iron bars, or meshed wire, placed in it when it is being molded
to shape, it is known as re-enforced concrete, and will thus form bridge floors,
bridge spans, and the upper floors of buildings which must support great weight.
In marine use, concrete is limited because of its weight, It may be used as
permanent ballast in the bilges of steel ships, and is an effective protection from
corrosion when applied to absolutely clean iron or to iron surfaces covered with
closely adhering red rust. When so used, cement may be mixed with water and applied
with a brush, or it may be mixed in the proportion of about two pans sand and one
part cement and applied wet, with a trowel, in a layer varying from 1/4 inch to any
thickness desired. In this way ships' tanks, bunkers, and bilges are protected, as
the mixture forms a close bond with the iron. In no case will this bond form if the
iron is oil coated.
Aggregates

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
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
is a broad category of coarse particulate material used in construction, including
sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates
are a component of composite materials such as concrete and asphalt concrete
serves as reinforcement to add strength to the overall composite material
due to the relatively high hydraulic conductivity value as compared to most soils,
aggregates are widely used in drainage applications such as foundation and french
drains, septic drain fields, retaining wall drains, and road side edge drains
are also used as base material under foundations, roads, and railroads.
Types of Aggregates
• Crumb. Porous aggregates with more or less spheroidal shapes.
• In angular blocks. Aggregates formed Of two more or less flat faces, which when cut
form edges and these lead to vertices. In short, their shape is similar to irregular
geometrical polyhedrons. The faces of the aggregates fit well with the faces of their
adjacent aggregates.
• In sub-angular blocks. Similar to the above, but the blocks are less defined. The faces
are not as flat, the edges are blunt and there are hardly any vertices. Neither do the
aggregates fit so well in the microstructure of angular blocks.
• Prismatic. Angular blocks, like a prism, in which the vertical dimension predominates
with regard to the other two. They are normally too large to be able to observe them in a
microscope.
• Platy. Aggregates with a leafy shape, in which the vertical dimension is much shorter
than the other two.
Admixtures are those ingredients in concrete other than portland cement, water, and
aggregates that are added to the mixture immediately before or during mixing.
Classification of Admixture by Function
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Water-reducing admixtures usually reduce the required water content for a concrete
mixture by about 5 to 10 percent. Consequently, concrete containing a waterreducing admixture needs less water to reach a required slump than untreated
concrete. The treated concrete can have a lower water-cement ratio. This usually
indicates that a higher strength concrete can be produced without increasing the
amount of cement. Recent advancements in admixture technology have led to the
development of mid-range water reducers. These admixtures reduce water content by
at least 8 percent and tend to be more stable over a wider range of temperatures.
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Mid-range water reducers provide more consistent setting times than standard water
reducers.
Retarding admixtures, which slow the setting rate of concrete, are used to
counteract the accelerating effect of hot weather on concrete setting. High
temperatures often cause an increased rate of hardening which makes placing and
finishing difficult. Retarders keep concrete workable during placement and delay
the initial set of concrete. Most retarders also function as water reducers and may
entrain some air in concrete.
Accelerating admixtures increase the rate of early strength development, reduce the
time required for proper curing and protection, and speed up the start of finishing
operations. Accelerating admixtures are especially useful for modifying the
properties of concrete in cold weather.
Superplasticizers, also known as plasticizers or high-range water reducers (HRWR),
reduce water content by 12 to 30 percent and can be added to concrete with a lowto-normal slump and water-cement ratio to make high-slump flowing concrete. Flowing
concrete is a highly fluid but workable concrete that can be placed with little or
no vibration or compaction. The effect of superplasticizers lasts only 30 to 60
minutes, depending on the brand and dosage rate, and is followed by a rapid loss in
workability. As a result of the slump loss, superplasticizers are usually added to
concrete at the jobsite.
Corrosion-inhibiting admixtures fall into the specialty admixture category and are
used to slow corrosion of reinforcing steel in concrete. Corrosion inhibitors can
be used as a defensive strategy for concrete structures, such as marine facilities,
highway bridges, and parking garages, that will be exposed to high concentrations
of chloride. Other specialty admixtures include shrinkage-reducing admixtures and
alkali-silica reactivity inhibitors. The shrinkage reducers are used to control
drying shrinkage and minimize cracking, while ASR inhibitors control durability
problems associated with alkali-silica reactivity.
Types of Admixtures
1.Retarding admixtures - slow down the hydration of cement, lengthening set time.
Retarders are beneficially used in hot weather conditions in order to overcome
accelerating effects of higher temperatures and large masses of concrete on concrete
setting time. Because most retarders also act as water reducers, they are frequently
called water-reducing retarders.
2. Accelerating admixtures- Accelerators shorten the set time of concrete, allowing a
cold- weather pour, early removal of forms, early surface finishing, and in some cases,
early load application. Proper care must be taken while choosing the type and proportion
of accelerators, as under most conditions, commonly used accelerators cause an increase
in the drying shrinkage of concrete.
3. Super plasticizers - also known as plasticizers, include water-reducing admixtures.
Compared to what is commonly referred to as a "water reducer" or "mid-range water
reducer", superplasticizers are "high-range water reducers". High range water reducers
are admixtures that allow large water reduction or greater flow ability (as defined by
the manufacturers, concrete suppliers and industry standards) without substantially
slowing set time or increasing air entrainment.
Each type of super plasticizer has defined ranges for the required quantities of concrete
mix ingredients, along with the corresponding effects. They can maintain a specific
consistency and workability at a greatly reduced amount of water. Dosages needed vary by
the particular concrete mix and type of super plasticizer used. They can also produce a
high strength concrete. As with most types of admixtures, super plasticizers can affect
other concrete properties as well. The specific effects, however, should be found from
the manufacturer or concrete supplier.
4. Water reducing admixtures - require less water to make a concrete of equal slump, or
increase the slump of concrete at the same water content. They can have the side effect
of changing initial set time. Water reducers are mostly used for hot weather concrete
placing and to aid pumping. A water-reducer plasticizer, however, is a hygroscopic
powder, which can entrain air into the concrete mix via its effect on water's surface
tension, thereby also, obtaining some of the benefits of air-entrainment.
5. Air-entraining admixtures - air-entraining agents entrain small air bubbles in the
concrete. The major benefit of this is enhanced durability in freeze-thaw cycles,
especially relevant in cold climates. While some strength loss typically accompanies
increased air in concrete, it generally can be overcome by reducing the water-cement
ratio via improved workability (due to the air- entraining agent itself) or through the
use of other appropriate admixtures. As always, admixtures should only be combined in a
concrete mix by a competent professional because some of them can interact in undesirable
ways.
Purpose of Admixture in Concrete
• producers use admixtures primarily to reduce the cost of concrete construction
• to modify the properties of hardened concrete
• to ensure the quality of concrete during mixing, transporting, placing, and curing
• to overcome certain emergencies during concrete operations
• certain admixtures, such as pigments, expansive agents, and pumping aids are used only
in extremely small amounts and are usually batched by hand from premeasured containers
Pre stressing/ Pre stressed concrete
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is a method for overcoming concrete's natural weakness in tension
It can be used to produce beams, floors or bridges with a longer span than is
practical with ordinary reinforced concrete.
Uses of Concrete
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Concrete has long been used for the foundations of structures of all kinds, and for
filling in the span drills of arches or the hearting and backs of walls.
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Of late years, as the material has improved, it has been employed for many other
purposes, a few only of which can now be mentioned,
The walls of ordinary houses, as well as the more massive walls of engineering
structures, are now frequently built in concrete, either in continuous mass or in
blocks.
Concrete is also used for walls in the form of slabs fitted into timber quartering:
and in hollow blocks, something like those Of terra cotta, filled in With inferaor
material
This material is also adapted for arches, for stairs, for flooring of different
kinds and even for roofs.
It can easily be made in slabs well fitted for paving and by the use of wooden
moulds can readily be cast in the form of window sills, lintels, dressings of all
kinds, steps, etc., and can even be used for troughs and cisterns.
Drain pipes and segments of sewers are also sometimes made of concrete. It was
thought that the acids in sewers might act upon the cement, but this has been found
practically not to be the case.
This material has been largely used in making the Paris sewers, and also
occasionally in this country.
Construction Joints- during the concrete pour, any break in the work can cause the
already poured concrete to harden enough to prevent new Concrete from bonding adequately.
This requires the use of construction joints, also known as pour joints.
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Reinforcement is placed in the old concrete prior to hardening, which extend into
the space where the new concrete will be poured. This ensures that the entire
structure acts as one piece rather than moving independently over time.
Construction joints may also be used to provide additional support between floor
levels or at corners where they will be hidden in the final product. It is
important to understand how to place construction joints, especially at stress
points, to ensure that structural integrity is not compromised.
Three Types of Concrete According to Weight
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Light Weight Concrete
• Low Density Concrete- is used for insulation purposes. Its unit weight would
rarely exceed 50 pounds per cubic foot or 800 kg per cubic meter.
• Moderate Strength Concrete- has a unit weight of 360 to 960 kg, per cubic
meter with a compressive strength of 70 to 176 kg. per square centimeter
commonly used to fill light gauge steel floor panels.
• Structural Concrete- has similarity in characteristics with that of medium
stone concrete. It weighs 90 to 120 pounds per cubic foot or 1440 to 1920 kg.
per cubic meter used in buildings roads, bridges, etc.
Medium Stone Concrete - is an structural concrete. It weighs from 145 to 152 pounds
per cubic foot of 2325 to 2435 kg. per cubic meter.
Heavy Weight Concrete -is used as shield against gamma rays reactor and other
similar structures. It is also used as counter weight for lift bridges. The
contents of heavy weight concrete are cement, heavy iron ores, crushed rock, steel
scraps, punching or shot as fine aggregate. The weight of heavyweight concrete
depends upon the kind of aggregate used in mixing.
concrete
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is a rocklike or stone like material produced by combining coarse and fine
aggregates, Portland cement and water and allowing the mixture to harden in forms
of the shape and dimensions of the desired structures
the word concrete comes from the Latin word "concretus" meaning compact or
condensed, the past participle of "concresco", from "com-Il (together) and "cresco"
is the universal material of construction
in a wide range of properties can be obtained by appropriate adjustment of the
proportions of the constituent materials
Properties of Concrete
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Concrete has relatively high compressive strength, but significantly lower tensile
strength, and as such is usually reinforced with materials that are strong in
tension (often steel). The elasticity of concrete is relatively constant at low
stress levels but starts decreasing at higher stress levels as matrix cracking
develops.
Concrete has a very low coefficient of thermal expansion, and as it matures
concrete shrinks. All concrete structures will crack to some extent, due to
shrinkage and tension. Concrete which is subjected to long-duration forces is prone
to creep.
Tests can be made to ensure the properties of concrete correspond to specifications
for the application.
The density of concrete varies, but is around 150 pounds per cubic foot (2,400
kg/m3 or 4,050 lb/yd3).
Types of Concrete
• Regular concrete-is the lay term describing concrete that is produced by following the
mixing instructions that are commonly published on packets of cement, typically using
sand or other common material as the aggregate, and often mixed in improvised containers.
This concrete can be produced to yield a varying strength from about 10 MPa (1450 psi) to
about 40 MPa (5800 psi), depending on the purpose, ranging from blinding to structural
concrete respectively. Many types of pre-mixed concrete are available which include
powdered cement mixed with an aggregate, needing only water
• High-strength concrete- has a compressive strength generally greater than 6,000 pounds
per square inch (40 MPa = 5800 psi). High-strength concrete is made by lowering the
water-cement (WIC) ratio to 0.35 or lower. Often silica fume is added to prevent the
formation of free calcium hydroxide crystals in the cement matrix, which might reduce the
strength at the cement-aggregate bond.
• Stamped concrete- is an architectural concrete which has a superior surface finish.
After a concrete floor has been laid, floor hardeners (can be pigmented) are impregnated
on the surface and a mold which may be textured to replicate a stone / brick or even wood
is stamped on to give a attractive textured surface finish. After sufficient hardening
the surface is cleaned and generally sealed to give a protection. The wear resistance of
stamped concrete is generally excellent and hence found in applications like parking
lots, pavements, walkways etc.
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Decorative stones such as quartzite, small river stones or crushed glass are
sometimes added to the surface of concrete for a decorative "exposed aggregate"
finish, popular among landscape designers.
The Three Types of Joints
Control Joints -these joints are also called contraction joints, which adequately
describes their purpose. Control joints are strategically placed throughout concrete
members or slabs to provide room for movement due to weather and time, such as
temperature changes, shrinkage and deformation.
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The joint is not a complete break in the concrete. Instead, it is a joint that goes
one-third of the way through the concrete. This weakens the surface of the concrete
while maintaining the structural integrity. The idea is that the joint will allow
any cracks that may form to occur along the control joint and not in other areas of
the surface.
Control joints are usually placed partially through the underlying foundation,
whether it is a slab, wall or other, in order to ensure that the concrete retains
its structural integrity and water tightness. Because of the naturally uneven
nature of concrete cracks and the steel that is used to reinforce the joint, a
control joint ensures that no movement occurs along the joint as time progresses.
Isolation Joints- also known as expansion joints, isolation joints are similar to control
joints except that the joint goes straight through the concrete. Isolation joints allow
the concrete to move along the joint without compromising the strength of the structure.
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Generally, these joints are positioned at stress points within a concrete slab or
at junctures, such as where walls meet the concrete. When construction involves the
use of columns, isolation joints are necessary at the base of the column where it
meets the concrete slab below. As time passes and the pressure of the structure as
well as weathering impacts the column, it will naturally rotate and settle. The
isolation joint endures that the column can move while remaining in place and
providing the required support to the overall structure.