ce60 properties of civil engineering materials

University of California, Berkeley

Department of Civil and Environment Engineering

CE60 PROPERTIES OF CIVIL

ENGINEERING MATERIALS

Laboratory Handouts



INSTRUCTIONS ON PREPARATION OF REPORTS

1.

Suggested Form for Reports:

a.

Cover : A special cover page will be provided for each laboratory report. It will show the course number, experiment title, and will have blank space for student name. It will also contain a list of items to be included in the report with the number of points to be given to each item. Be sure to start your report with the cover page since it will serve as a grade sheet for the laboratory. b.

Objective : Give a brief statement of the Objective or Introduction to the lab experiment. c.

Experiment Conditions : Report on the material used, kind of testing apparatus, and principal features of the test. Each report should be structured so that the reader will understand how the experiment was performed, what the results are, and what they mean. This will often require you to restate or repeat certain information which appeared in the laboratory handout. d.

Experimental Results : State the principal findings and refer to tables or diagrams (if any) where details may be found. Sometimes the best way to show experimental results is with a figure which contains a graph of the data. An example of a graph is shown on next page. Include a suitable chart title. Make sure to label the horizontal and vertical axis and identity the units. Identify and label all critical points. e.

Discussion : Compare your results with those given in lecture or other references.

Give reasons for discrepancies if serious differences appear to exist. Compare the characteristics of materials, experimental procedures, types of specimens, etc. involved in the experiment. Comment on modes of failure when tested to rupture.

Mention limitations of experiment. State the significance of the experiment. Include several sentences on applicable items. f.

Conclusions : One or two sentences are usually sufficient. g.

Appendix : Schematic sketches (or photos) of special apparatus and tables can be put in an appendix if you wish. This is also a good place for sample calculations. In general, do not include all computations, merely one complete set. Always include the data sheets you used to collect data during the laboratory session. It is recommended that you make a Xerox copy or PDF of the data sheets before handing in the original data sheet with the report.

Reports must be typed and submitted in a folder or stapled in one coner. All work must be your own. Reports will have an assigned date when they are due, usually one week after the laboratory period.

2.

Suggested Formats for Preparing Figures:

Show data points clearly. Small "o" or special symbols such as “ □ ” or “+” can be used to differentiate data on different curves. Use of "x" data points are acceptable, but can get sloppy. A dot is hard to see so do not use small dots for data points. A sample "Stress-Strain" curve is shown on the next page.



Figure 1 – Example of how a plot should look like



CE60 PROPERTIES OF CIVIL ENGINEERING MATERIALS

Laboratory Experiment I

STRESS-STRAIN BEHAVIOR OF BUNGEE CORD IN TENSION

1.

OBJECTIVES

1.

Determine the mechanical properties of bungee cords and the materials of which they are constructed.

2.

Conduct experiments to find the relationship between applied mechanical loads and elongation of the samples.

3.

Convert the "Load" and "Elongation" data to "Stress" and "Strain" data.

Each student will leave the laboratory period with his/her own set of data and will prepare a short report to be handed in one week later.

2.

MATERIALS AND EQUIPMENT

1.

Permanent Marker

2.

Pencil/pen

3.

10 – 3”x6” cylinder molds

4.

12” ruler

5.

36” ruler

6.

Caliper

7.

Bungee cord

8.

1 steel bucket

9.

1 plastic bucket

3.

BACKGROUND

1.1

Safety

This experiment has the potential for a heavy bucket filled with sand to fall on an individuals’ foot or the bungee cord to whip and hit an individual in the eye. All students are required to wear safety glasses and closed-toe shoes.

1.2

Strain

Strain,

ε

, is defined as the change in length divided by the initial length:

The units for strain are dimensionless since it is length divided by length. Strain is sometimes written as a percentage and sometimes it is simply written as a number and if it is less than one it is written as a decimal number. For instance, if the length changes by 5% it can be written as 0.05 in/in, (or cm/cm) or just 5%. Note that the in/in or cm/cm is sometimes used to remind the reader of the dimensionless nature of strain, but it can also simply be written as



“0.05”. For polymers, (particularly rubber), the deformations can be double or even four times the original length, and in those cases strain is usually written as percentage (e.g.

300%).

1.3

Engineering and True Stress

Engineering stress, σ

E

is defined as the load applied to the body of a constant (initial) area .

True stress, σ

T

is defined as the load applied to the body of an instantaneous area.

The units for both engineering stress and true stress are force per unit area. In the U.S.

Customary system stress is usually given as pounds per square inch (psi) or kips per square inch (ksi) (1000 pounds = 1 kip). In the SI system stress is given in newton per square meter, which is equal to a "pascal" (Pa) or a megapascal (MPa) (1,000,000 Pa = 1 MPa). To convert from psi to Pa you multiply by 6.8948 x 10 3 . In this laboratory report you may use either the

U.S. Customary or SI units.

1.4

Plastic Deformation

Some materials exhibit a plastic (permanent) deformation, which basically means that after being loaded and unloaded it will not return to its original (initial) size.

4.

EXPERIMENTAL PROCEDURE

1.

Characterize the bungee cord your group is given. This includes, but is not limited to the following: Make a sketch showing the dimensions of your bungee cord. Indicate if the given material is flexible, hard, shiny, colored, painted, metallic, or any other features.

2.

Mark a 2-inch gage length approximately in the center of the bungee cord using a permanent marker. The gage length will be used to measure the "elongation" as a load is applied to the sample. Also make marks as close to the hook ends as possible to measure the overall length of the bungee cord. The overall length will be used to measure the permanent deformation when the bungee cord is unloaded.

3.

Hang one end of the bungee cord to the test apparatus and the other end to a plastic bucket. Make a sketch of the arrangement you find for supporting the sample and applying the load.

4.

Measure and record on the data sheet provided the initial gage length, diameter, and overall length. The overall length is measured between the hooks of the bungee cord.

The initial data point is when the plastic bucket is empty (Load equals zero).

5.

Using the sand, apply a load of one-pound. Measure the change in gage length and the diameter (Do not measure the overall length until the bungee cord is unloaded).

Measure the length in decimal units rather than fractions (Note: Both scales are on your ruler).

6.

Continue to apply a load of one-pound increments and measuring the change in gage length and diameter until reaching 10 pounds.

7.

When the load is at 10 pounds, measure the change in gage length and diameter.

Unload the bungee cord by removing the sand from the plastic bucket and measure



the change in gage length, diameter, and the overall length. Reload the sample with the 10 pounds and measure the change in gage length and diameter.

8.

Continue adding load in one-pound increments and measuring the change in gage length and diameter.

9.

When the load is at 20 pounds, perform the tasks in bullet 7. Make sure to measure the overall length when the bungee cord is unloaded.

10.

Continue adding load in one-pound increments and measuring the change in gage length and diameter.

11.

When the calculated difference in gage length between the one-pound increments is

0.1 inches or less, continue to collect 10 additional data points of one-pound increment. After collecting the additional 10 data points, the experiment can be terminated.

12.

Each group should look over their data sheet to be sure that the sheet contains all of the information needed to complete the report. This includes initial diameter, initial overall length of your bungee cord (i.e. the length between the hooks), and the change of gage length and diameter with load applied. There should also be data collected of the overall length when the load was removed at the 10-pound increments (10, 20, 30, etc.).

13.

An instructor will sign the data sheet after the test is terminated and the data sheet is satisfactory. Make sure to include on the data sheet the names of all team members in the group.

5.

REPORT

Each student in the class is responsible for their own report. The report is due one week after the lab is performed unless otherwise noted.

1.

The report should have a brief "Introduction" which describes how the laboratory exercise was structured and what your group accomplished. It should be detailed enough for a Civil Engineer who is not familiar with the "Stress-Strain Behavior of

Bungee Cords" to be able to understand the laboratory exercise and your results.

2.

Calculate the "Engineering Stress" and "True Stress" at each one-pound increment.

Show a sample calculation and provide a table with all the calculated values in the report.

3.

Calculate the "Strain" for each increment of the load. Show a sample calculation and provide a table with all the calculated values in the report.

4.

Include the following plots using the collected data and calculated values: a.

Load vs. Elongation [Plot the load on the vertical axis] b.

Engineering Stress vs. Strain [Plot the stress on the vertical axis], and c.

True Stress vs. Strain [This plot can be on the same graph with the

Engineering Stress vs. Strain]

5.

Using the results the experiment, determine the number of bungee cords necessary to support a 4,000-pound load when the strain on each cord is 50%.




Laboratory Experiment I

STRESS-STRAIN BEHAVIOR OF BUNGEE CORD IN TENSION

NAME:____________________________

GRADE SHEET

1.

Organization & Neatness (2) ______

2.

Enclosure (Summary sheet, calculations, etc…)

3.

Introduction

(2) ______

(2) ______

4.

Calculations of Engineering and True Stress

5.

Calculations of Strain

6.

Plot of Load vs. Elongation

7.

Plot of Engineering Stress vs. Strain

8.

Plot of True Stress vs. Strain

9.

Problem solution of 4,000 lb car

10.

Test Results (Data sheet, Completeness, Accuracy &

Consistency)

TOTAL

(2) ______

(2) ______

(2) ______

(2) ______

(2) ______

(2) ______

(2) ______

(20) ______

UNIVERSITY OF CALIFORNIA, BERKELEY

Department of Civil and Environmental Engineering


Laboratory Experiment I

BUNGEE CORD STRESS -‐ STRAIN MEASUREMENTS

Date: Name:

Lab Partners:

SKETCH OF SAMPLE: LOAD

(lbs)

GAGE LENGTH

(in.)

DIAMETER

(in.)

OVERALL LENGTH

(in.)

SKETCH OF TEST APPARATUS:

THIS SHEET IS TO BE COMPLETED BEFORE LEAVING THE LABORATORY Checked by:________________________________




Laboratory Experiment II

TENSILE TEST OF STEEL

1 INTRODUCTION

The elastic and plastic properties of a metallic material are determined by means of a tensile test. The collected tensile test data is used to plot a stress vs. strain curve. Figure 1 shows a typical stress-strain curve for low-carbon steel. The stress, shown along the vertical axis in

Figure 1, is called "engineering stress" since it is obtained by dividing the applied "load" by the original cross-sectional area. As the specimen is deformed the actual cross-sectional area will decrease, but the engineering stress does not take that into account.

Figure 1 – Typical engineering stress-strain diagram for low-carbon steel

The “total” strain, shown along the horizontal axis in Figure 1, is obtained by dividing the change in length by the original length. The total strain at any point along this curve is the combination of the elastic and plastic strains. Before reaching the upper yield strength, the plastic strain is zero and the total strain is equal to the elastic strain. Beyond the upper yield strength, the elastic strain can be determined by unloading the specimen during the test, see point A in Figure 1. Once the load is removed the specimen shortens by an amount equal to the stress at point A divided by elastic (Young's) modulus. This recoverable amount is the elastic part of the strain. The unrecoverable, or permanent, amount is the plastic strain.



The following quantities are obtained from a stress-strain curve and are frequently used as a quantitative measure of the plastic behavior of steel.

• Upper yield strength : The maximum stress reached in the specimen prior to the onset of significant plastic deformation. This is also sometimes called the "Upper yield point".

• Lower yield strength : Stress corresponding to the horizontal portion of the stressstrain curve immediately following the beginning of plastic deformation. This is sometimes called the "Lower yield point".

These quantities are characteristic of low-carbon steel in an undeformed state. For cold worked (i.e. plastically deformed) low-carbon steel the stress-strain curve would look like the curve drawn from point A in Figure 1. For a specimen that has been unloaded from point A and then reloaded it would return to point A and begin to plastically deform without showing the distinct upper and lower yield points. That same type of stress-strain curve is found for most metals and metal alloys, and thus for most metals one only talks about the "yield point".

A more useful definition of yield point for use in general is the "0.2% offset yield strength", which is defined as follows: The "0.2% offset yield strength" is the stress corresponding to the point on the stress-strain curve where there is 0.2% (i.e. 0.002 in/in) permanent strain.

The 0.2% offset yield is obtained by plotting an imaginary "unloading" curve, which strikes the strain axis at 2000 microstrain. This is shown on the sample stress-strain curve shown in

Figure 2 where the early portion of the stress-strain curve for a low carbon steel has been drawn with an expanded "microstrain" axis. Note: The lower scale goes with the lower curve in Figure 2. The "proportional limit" is the point where the initial linear part of the curve ends.

The modulus of elasticity is the initial slope of the stress-strain curve, which you can see is

29.5 x 10 6 psi for the steel specimen in Figure 2. Several other important parameters are shown in Figure 2. One of these is the ultimate tensile strength (U.T.S.), which is defined as follows:

• Ultimate tensile strength : The stress corresponding to the maximum engineering stress sustained by the specimen prior to fracture. Note that it is sometimes just called the "tensile strength." The 0.2% offset yield point and the U.T.S. are often used in specifications to characterize a metal alloy's quality.



Figure 2 – Engineering stress-strain curve for low-carbon steel as measured in this laboratory

Another property depicted in the stress-strain curve is the energy absorbing ability of the alloy under the specific tensile test condition. There are usually no notches or cracks to act as stress concentrations and the total amount of elongation of the test specimen is a measure of the work necessary to fracture the alloy under ideal conditions. There are two parameters, which are used to characterize this property. They are "elongation" and "reduction in area," which are defined as follows:

•

Elongation : Average plastic strain for a specific gauge length at the time of fracture

•

(expressed as a percentage).

Reduction in Area : Initial cross-section area minus final cross-sectional area at the point of fracture divided by the initial cross-sectional area expressed as a percentage.

2 TEST PROCEDURES

Parts 1, 2, and 3 will be done by laboratory staff prior to class.

1.

Determine the average cross-section dimension of the specimen with a micrometer caliper. Using a center punch device lightly mark eleven 1-inch spacing marks along the length of the steel bar. Measure Rockwell hardness of the specimen using the Bscale (The hardness test will be covered in Laboratory III).

2.

Screw both ends of the specimen into the nut attachments of the testing machine.



3.

Screw the upper end of the extensometer into the upper end of the specimen first followed by the lower ends. Place the specimen so that punch marks and the dial indicator face the operator of the testing machine.

4.

Determine the gauge length and multiplication ratio (x2) of the extensometer.

Determine the value of the divisions on the dial indicator. Remove the reference bar.

Adjust the loading dial on the testing machine and the extensometer to read zero.

Start testing machine, close the unloading valve, then open the loading valve so that the platform of the testing machine just starts to move up. (Approx. 1/4 in.) Close the loading valve and screw the lower spherical nut until it just makes contact with the stationary head of the testing machine. Check extensometer, and re-zero both load indicator and extensometer if necessary.

5.

Sequence of reading (elongation vs. load) for a low carbon steel specimen. a.

Using the eight-inch extensometer with a multiplication ratio of two, having the smallest dial graduated in 1/10,000 of an inch and a range of 0.500 inch. b.

Apply load starting with a slow rate and take simultaneous observations of load and dial reading without stopping the machine. c.

Up to the upper yield point apply load at a rate of 1000 lb. per minute using the pacing disk on the testing machine. After the upper point is reached, shut the pacing disk off and apply the load at a rate at which reading can be taken and recorded. d.

Using dial indicator. Readings are to be taken at the following intervals:

(a) Every 0.001 inch on dial up to upper yield point.

(b) Every 0.01 inch interval on dial from upper yield point to 0.2 inch on dial.

(c) Every 0.05 inch interval on dial from 0.2 inch to 0.4 inch.

(d) After obtaining the 0.4 inch dial readings, close the loading valve

(DO NOT UNLOAD), replace reference bar and remove extensometer. e.

Using divider and scale. Continue applying load. When the gauge length

(originally 8 inches) has increased to 8.3 inches as measured with dividers and scale, observe the load and record. Thereafter, for each 0.2 inch increase in gauge length observe the load and record. Also make sure to record the ultimate and fractured loads.

6.

Fit the fractured parts together in the testing machine and measure the final length of each of the original one inch gauge lengths. Observe the location of the fracture, and then determine the diameter of the minimum cross-section, using the pointed-end micrometer.

7.

Remove the fractured specimen from the machine. Observe the character of the fracture, check for magnetism at the necked ends of specimen and measure final

Rockwell hardness.

3 REPORT

1.

Each student in the class will be responsible for his or her own report on the laboratory. Each report should have a brief "Introduction" which describes how the laboratory exercise was structured and what your group accomplished. It should be


Department of Civil and Environment Engineering detailed enough for a Civil Engineer who is not familiar with the experiment to be able to understand the laboratory exercise and your results. You can and should attach a copy of this Laboratory Handout and make references to specific information contained herein. The completed data should be included in the report.

2.

Create one plot with the entire stress-strain curve for the steel specimen. Create a second that includes only data for the elastic (Young’s) modulus and the yield strength of the steel. The graph must include a title and the axes must be properly labeled. Your plots should be similar to Fig. 2 in this Laboratory Handout.

3.

From your data determine: a) Elastic modulus (show how it was obtained) b) 0. 2% offset yield strength. c) Did your sample show both upper and lower yield points? Give the values. d) Ultimate tensile strength. e) Total elongation, (give the % elongation for the 2" gauge length which includes the fracture). f) Reduction in area (give this in % the area at the necked fracture point changed from the original).

4.

What are the magnitudes of recoverable (elastic) strain and permanent (plastic) strain in the specimen, if it was to be unloaded after reaching a stress level of 30,000 psi?

45,000 psi?

5.

The "true stress" was defined in Lab I. Take Fig. 2 in the Laboratory Handout and indicate where the true stress vs. engineering strain curve would fall.

4 REFERENCES

1.

ASTM International, ASTM E8/E8M-‐13a – Standard Test Methods for Tension

Testing of Metallic Materials, 2013.




Laboratory Experiment II

STRESS-STRAIN BEHAVIOR OF STEEL IN TENSION

NAME:____________________________

GRADE SHEET

1.


2.


3.

Introduction

(2) ______

(2) ______

4.

Complete Stress-Strain Curve (both parts)

5.

Computation of the Elastic Modulus

6.

Computation of 0.2% Offset Yield Strength

7.

Computation of the Ultimate Tensile Strength

8.

Computation of the Elongation

9.

Computation of the Reduction in Area

10.

Discussion of Recoverable and Permanent Strains

11.

Discussion of True Stress

12.


Consistency of Results)

TOTAL

(4) ______

(2) ______

(2) ______

(1) ______

(1) ______

(1) ______

(1) ______

(1) ______

(1) ______

(20) ______




Laboratory Experiment II

TENSION TEST OF STEEL

Date: Name:

Lab Partners:

Group Number:

Measurements using

EXTENSOMETER

Load, lbs

Length change

(x 2), in.

0 0

GENERAL INFORMATION:

Specimen Id.

Material

Overall Length, in.

Length between shoulders, in.

Extensometer gage length, in.

Diameter of ends, in.

Diameter of test section, in.

Elongation over 2 inches at fracture, in.

Diameter of reduced section, in.

Machine used

Extensometer used

Rate of loading, lbs / min.

Mannur of failure (circle one)

Hardness before tensile test

Hardness after tensile tes

Ductile / Brittle

B-‐scale =

B-‐scale =

Sketch of Failure:


EXTENSOMETER (CONT.)

Load, lbs

Length change

(x 2), in.


DIVIDERS

Load, lbs

Length change, in.

Inch No.

1

Elongation for each inch

Initial Length, in.

1

8

9

6

7

10

4

5

2

3

1

1

1

1

1

1

1

1

1

Final Length, in.

THIS SHEET IS TO BE COMPLETED BEFORE LEAVING THE LABORATORY Checked by:___________________________




Laboratory Experiment III

HARDENABILITY OF STEEL – THE JOMINY END-QUENCH TEST

1 OBJECTIVES

1.

The heat treatment of steel is one of the best examples in Materials Science of the importance of non-equilibrium microstructures. The student is introduced to the process of heat treatment in this laboratory, and to the measurement of how the properties change.

2.

The Jominy Test is sometimes called an "end-quench" test since it consists of taking a small steel bar 100 mm (4 in) long and 25.4 mm (1 in) in diameter which has been heated to a temperature where it is completely transformed to the face centered cubic (fcc) form of iron,

(austenite, γ ), and spraying a jet of water against one end of the bar. This is schematically shown in Fig. 1(a). The "cooling rate" varies along the bar as shown in Fig. 1(b) because the surface cools very rapidly, but sections of the bar behind the quenched surface cool progressively more slowly. When the whole bar is cold, the hardness is measured along its length. A steel of "high" hardenability will show a uniform high hardness along the whole length of the bar, but a steel of medium hardenability will show a decreasing hardness along the length of the specimen as shown in Fig. 1(c).

Figure 1 – (a) Schematically shows how the Jominy “end-quench” test is conducted, (b) shows the cooling rate, and (c) shows how the hardness varies along the specimen, (after L.H. Van Vlack,

Materials for Engineering, Addition-Wesley, 1982.)



2 TEST PROCEDURE

This is a standard test for "Hardenability of Steel" and you will be provided with a copy of the

ASTM Standard A255.

1.

Read Section 1.0 Scope in ASTM A255

2.

Read Section 6.4 Hardness Measurement. This section describes what we will do in the laboratory.

3.

Read Section 7 Plotting Test Results. This will be part of the Report for this laboratory.

3 REPORT

Each student in the class will be responsible for his or her own report. The report will be due one week after the period in which the data was collected.

1.

Each report should have a brief Introduction which describes how the laboratory exercise was structured and what your party accomplished. It should be detailed enough for a Civil Engineer who is not familiar with the Jominy End-Quench Test to be able to understand the laboratory exercise and your results. You can and should attach a copy of the most recent Laboratory Handout and make references to specific information contained therein.

2.

Plot the average hardness readings vs. the distance from the quenched end of the specimen. Follow the format of Fig. 4 in the ASTM Standard A255 in which the ordinates represent hardness values and the abscise represent the distance from the quenched and of the specimen at which the hardness determinations were made. Note that the next paragraph calls for more data to be added to this plot. This graph will be similar to Fig. 4 in the ASTM A255 Standard.

3.

The steel used in this experiment is very close to a "1050" steel. The TTT diagram for

1050 steel is shown on the next page. The "E-Q Hardenability" curve shown at the bottom of the page refers to the expected Jominy End-Quench results for 1050 steel. Plot the values for 1050 on the same graph as your results from the experiment. How closely do the two curves compare? You should take the "data" for this from the "E-Q

HARDENABILITY" graph on the bottom of the 1050 page which is also listed as "page

19."

4.

Put the TTT diagram for 1050 steel in your report and indicate on it the approximate cooling path for the quenched end of your specimen. Note the "Approximate Cooling

Rate" which is given in Fig. 4 in the ASTM A255 Standard. What is the most plentiful phase in your specimen at the quenched end?

5.

Indicate on the TTT diagram for 1050 steel the approximate cooling path for the portion of your specimen which is 2.5 inches (40 Jominy units) from the quenched end. What are the most plentiful phases in you specimen at this location 2.5 inches (40 Jominy units) from the quenched end?






Laboratory Experiment III

HARDENABILITY OF STEEL – THE JOMINY END-QUENCH TEST

NAME:____________________________

GRADE SHEET

1.


2.


3.

Introduction

(2) ______

(2) ______

4.

Plot Hardness Readings vs. Distance (Measured data)

5.

Comparison to 1050 (Including Plot of 1050 data)

6.

Discussion of TTT & Cooling Curves (See Section 3

Report bullets 4 and 5)

7.


Consistency)

TOTAL

(6) ______

(2) ______

(4) ______

(2) ______

(20) ______




Laboratory Experiment III

HARDENABILITY OF STEEL: THE JOMINY END-‐QUENCHED TEST

Date: Name:

Lab Partners:

Equipment Number:


Material

Hardness Tester Equipment

Indenter Type

Weight (kg)

Scale

Calibration (3 points)

NOTE 1 -‐ Take readings every

Position inches

1 ,

1

Hardness; Rockwell C

2 3


Designation: A255 − 10

Standard Test Methods for

Determining Hardenability of Steel

1

This standard is issued under the fixed designation A255; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ´ ) indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the Department of Defense.

1. Scope

1.1 These test methods cover the identification and description of test methods for determining the hardenability of steels.

The two test methods include the quantitative end-quench or

Jominy Test and a method for calculating the hardenability of steel from the chemical composition based on the original work by M. A. Grossman.

1.2 The selection of the test method to be used for determining the hardenability of a given steel shall be agreed upon between the supplier and user. The Certified Material Test

Report shall state the method of hardenability determination.

1.3 The calculation method described in these test methods is applicable only to the range of chemical compositions that follow:

Element Range, %

Carbon

Manganese

Silicon

Nickel

Chromium

Molybdenum

Copper

Vanadium

0.10–0.70

0.50–1.65

0.15–0.60

1.50 max

1.35 max

0.55 max

0.35 max

0.20 max

1.4 Hardenability is a measure of the depth to which steel will harden when quenched from its austenitizing temperature

( Table 1 ). It is measured quantitatively, usually by noting the

extent or depth of hardening of a standard size and shape of test specimen in a standardized quench. In the end-quench test the depth of hardening is the distance along the specimen from the quenched end which correlates to a given hardness level.

1.5 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.6

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents

2.1

ASTM Standards:

2

E18

Test Methods for Rockwell Hardness of Metallic Materials

E112

Test Methods for Determining Average Grain Size

2.2

ASTM Adjuncts:

ASTM Hardenability Chart

3

END-QUENCH OR JOMINY TEST

3. Description

3.1 This test method covers the procedure for determining the hardenability of steel by the end-quench or Jominy test. The test consists of water quenching one end of a cylindrical test specimen 1.0 in. in diameter and measuring the hardening response as a function of the distance from the quenched end.

4. Apparatus

4.1

Support for Test Specimen— A fixture for supporting the test specimen vertically so that the lower end of the specimen is a distance of 0.5 in. (12.7 mm) above the orifice of the water-quenching device. A satisfactory type of support for the standard 1.0-in. (25.4-mm) specimen is shown in

Fig. 1 .

N

OTE

1—A suitable support for other sizes and shapes of specimens is shown in Fig. X1.1

.

4.2

Water-Quenching Device— A water-quenching device of suitable capacity to provide a vertical stream of water that can be controlled to a height of 2.5 in. (63.5 mm) when passing through an orifice 0.5 in. (12.7 mm) in diameter. A tank of sufficient capacity to maintain the water temperature requirements of

6.3

with a small pump and control valves will be

1 These test methods are under the jurisdiction of ASTM Committee A01 on

Steel, Stainless Steel and Related Alloys and are the direct responsibility of

Subcommittee A01.15

on Bars.

Current edition approved May 1, 2010. Published June 2010. Originally approved in 1942. Last previous edition approved in 2007 as A255 – 07

´ 1

. DOI:

10.1520/A0255-10.

2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM

Standards volume information, refer to the standard’s Document Summary page on the ASTM website.

3 Standard ASTM Hardenability Charts (8 1 ⁄

2 by 11 in. pads of 50 charts) are available from ASTM International Headquarters. Order Adjunct No.

ADJA0255 .

Original adjunct produced in 1945.

*A Summary of Changes section appears at the end of this standard

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

Copyright by ASTM Int'l (all rights reserved); Thu Sep 26 19:48:33 EDT 2013

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1

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TABLE 1 Normalizing and Austenitizing Temperatures A

Steel Series

Ordered

Carbon

Content, max, %

0.25 and under

Normalizing

Temperature,

°F (°C)

Austenitizing

Temperature,

°F (°C)

1000, 1300, 1500,

3100, 4000, 4100

4300, 4400, 4500,

4600, 4700, 5000,

5100, 6100, B

8100, 8600, 8700,

8800, 9400, 9700,

9800

0.26 to 0.36, incl

1700 (925)

1650 (900)

1700 (925)

1600 (870)

2300, 2500, 3300,

4800, 9300

0.37 and over

0.25 and under

1600 (870)

1700 (925)

1550 (845)

1550 (845)

9200

0.26 to 0.36, incl

0.37 and over

0.50 and over

1650 (900)

1600 (870)

1650 (900)

1500 (815)

1475 (800)

1600 (870)

A A variation of ±10°F (6°C) from the temperatures in this table is permissible.

B Normalizing and austenitizing temperatures are 50°F (30°C) higher for the

6100 series.

A255 − 10 found satisfactory. The water-supply line shall also be provided with a quick opening valve.

5. Test Specimens

5.1

Wrought Specimens— End-quench specimens shall be prepared from rolled or forged stock and shall represent the full cross section of the product. If negotiated between the supplier and the user, the end-quench specimen may be prepared from a given location in a forged or rolled product or from a continuous cast billet. The test specimen shall be 1.0 in. (25.4

mm) in diameter by 4.0 in. (101.6 mm) in length, with means for hanging it in a vertical position for end quenching.

Dimensions of the preferred specimen and of an optional

specimen ( Note 2 ) are given in

Figs. 2 and 3 . The specimen

shall be machined from a bar previously normalized in accordance with

6.1

and of such size as to permit the removal of all decarburization in machining to 1.0 in. round. The end of the specimen to be water cooled shall have a reasonably smooth finish, preferably produced by grinding. Normalizing may be waived by agreement between the supplier and the user. The previous thermal history of the specimen tested shall always be recorded.

5.2

Cast Specimens— A separately cast end-quench specimen may be used for non-boron steels. Cast specimens are not suitable for boron steel grades due to erratic results. A graphite or metal mold may be used to form an overlength specimen 1.0

in. (25.4 mm) in diameter which shall be cut to the standard specimen size. The mold may also be used to form a 1.25-in.

(31.8-mm) diameter specimen which shall be machined to the final specimen size. Cast tests need not be normalized.

N

OTE

2—Other sizes and shapes of test specimens are described in

Appendix X1 .

6. Procedure

6.1

Normalizing— The wrought product from which the specimen is to be prepared shall be normalized to ensure proper hardening characteristics. The sample shall be held at the temperature listed in

Table 1

for 1 h and cooled in air.

Tempering of the normalized sample to improve machinability is permitted.

6.2

Heating— Place the specimen in a furnace that is at the

specified austenitizing temperature ( Table 1 ) and hold at this

temperature for 30 min. In production testing slightly longer times up to 35 min may be used without appreciably affecting results. It is important to heat the specimen in such an atmosphere that practically no scaling and a minimum of decarburization takes place. This may be accomplished by heating the specimen in a vertical position in a container with an easily removable cover containing a layer of cast-iron chips with the bottom face of the specimen resting on the chips.

6.2.1 Other methods consist of placing the specimen in an appropriately sized hole in a graphite block or placing the specimen in an upright tube attached to a flat base, both of a heat-resistant metal, with the collar projecting for a tong hold.

Place a disk of graphite or carbon, or a layer of carbonaceous material such as charcoal, in the bottom of the tube to prevent scaling.

6.2.2 For a particular fixture and furnace, determine the time required to heat the specimen to the austenitizing temperature by inserting a thermocouple into a hole drilled axially in the top of the specimen. Repeat this procedure periodically, for example once a month, for each combination of fixture and furnace.

6.3

Quenching— Adjust the water-quenching device so that the stream of water rises to a free height of 2.5 in. (63.5 mm) above the 0.5-in. (12.7-mm) orifice, without the specimen in position. The support for the specimen shall be dry at the beginning of each test. Then place the heated specimen in the support so that its bottom face is 0.5 in. above the orifice, and turn on the water by means of the quick-opening valve. The time between removal of the specimen from the furnace and the beginning of the quench should not be more than 5 s. Direct the stream of water, at a temperature of 40 to 85°F (5 to 30°C), against the bottom face of the specimen for not less than 10 min. Maintain a condition of still air around the specimen during cooling. If the specimen is not cold when removed from the fixture, immediately quench it in water.

6.4

Hardness Measurement— Two flats 180° apart shall be ground to a minimum depth of 0.015 in. (0.38 mm) along the entire length of the bar and Rockwell C hardness measurements made along the length of the bar. Shallower ground depths can affect reproducibility of results, and correlation with cooling rates in quenched bars.

6.4.1 The preparation of the two flats must be carried out with considerable care. They should be mutually parallel and the grinding done in such a manner that no change of the quenched structure takes place. Very light cuts with water cooling and a coarse, soft-grinding wheel are recommended to avoid heating the specimen. In order to detect tempering due to grinding, the flat may be etched with one of the following etchant solutions:

N

OTE

3—5 % nitric acid (concentrated) and 95 % water by volume.

N

OTE

4—50 % hydrochloric acid (concentrated) and 50 % water by volume.



2


A255 − 10

FIG. 1 Test Specimen in Support for Water Quenching

FIG. 2 Preferred Test Specimen

FIG. 3 Optional Test Specimen

Wash the sample in hot water. Etch in solution No. 1 until black. Wash in hot water. Immerse in solution No. 2 for 3 s and wash in hot water. Dry in air blast.

6.4.1.1 The presence of lighter or darker areas indicates that hardness and structure have been altered in grinding. If such changes caused by grinding are indicated, new flats may be prepared.

6.4.2 When hardness tests are made, the test specimen rests on one of its flats on an anvil firmly attached to the hardness machine. It is important that no vertical movement be allowed when the major load is applied. The anvil must be constructed to move the test specimen past the penetrator in accurate steps of 1 ⁄

16 in. (1.5 mm). Resting the specimen in a V-block is not permitted.



3


6.4.2.1 The Rockwell tester should periodically be checked against standard test blocks. It is recommended that a test block be interposed between the specimen and the indenter to check the seating of the indenter and the specimen simultaneously.

For general statements regarding the use of test blocks and surface conditions, reference should be made to 4.7 and 5.2, respectively, of Test Methods

E18 .

6.4.3 Exercise care in registering the point of the indenter in relationship to the quenched end of the specimen as well as providing for accurate spacing between indentations. A lowpower measuring microscope is suitable for use in determining the distance from the quenched end to the center of the first impression and in checking the distance from center to center of the succeeding impressions. It has been found that with reasonable operating care and a well-built fixture, it is practical to locate the center of the first impression 0.0625

6 0.004 in.

(1.5

6 0.10 mm) from the quenched end. The variations between spacings should be even smaller. Obviously, it is more important to position the indenter accurately when testing low-hardenability steels than when testing high-hardenability steels. The positioning of the indenter should be checked with sufficient frequency to provide assurance that accuracy requirements are being met. In cases of lack of reproducibility or of differences between laboratories, indenter spacing should be measured immediately.

6.4.4 Readings shall be taken in steps of 1 ⁄

16 in. (1.6 mm) for the first 16 sixteenths (25.4 mm), then 18, 20, 22, 24, 28, and

32 sixteenths of an inch. Values below 20 HRC are not recorded because such values are not accurate. When a flat on which readings have been made is used as a base, the burrs around the indentation shall be removed by grinding unless a fixture is used which has been relieved to accommodate the irregularities due to the indentations.

6.4.4.1 Hardness readings should preferably be made on two flats 180° apart. Testing on two flats will assist in the detection of errors in specimen preparation and hardness measurement. If the two probes on opposite sides differ by more than 4 HRC points at any one position, the test should be repeated on new flats, 90° from the first two flats. If the retest also has greater than 4 HRC points spread, a new specimen should be tested.

6.4.4.2 For reporting purposes, hardness readings should be recorded to the nearest integer, with 0.5 HRC values rounded to the next higher integer.

7. Plotting Test Results

7.1 Test results should be plotted on a standard hardenability chart prepared for this purpose, in which the ordinates represent HRC values and the abscissae represent the distance from the quenched end of the specimen at which the hardness determinations were made. When hardness readings are taken on two or more flats, the values at the same distance should be averaged and that value used for plotting. A facsimile of the standard ASTM hardenability chart

3 on which typical hardenability curves have been plotted is shown in

Fig. 4 .

8. Index of Hardenability

8.1 The hardenability of a steel can be designated by a specific HRC hardness value or HRC hardness value range at

A255 − 10 a given Jominy (“J”) distance. Examples of this method are

J 4 ⁄

16 in. (6.4 mm) = 47 HRC min, J 7 ⁄

16 in. (11.1 mm) = 50

HRC max, and J 5 ⁄

16 in. (7.9 mm) = 38–49 HRC.

9. Report

9.1 Report the following information that may be recorded on the ASTM hardenability chart:

9.1.1 Previous thermal history of the specimen tested, including the temperature of normalizing and austenitizing,

9.1.2 Chemical Composition,

9.1.3 ASTM grain size (McQuaid-Ehn) as determined by

Test Methods

E112 , unless otherwise indicated, and

9.1.4 A prominent notation on the standard hardenability chart if any of the test specimens listed in Appendix X1 are used.

CALCULATION OF HARDENABILITY

10. Introduction

10.1 This method of Jominy Hardenability calculation from the chemical ideal diameter (DI) on a steel is based on the original work of M. A. Grossman and provides increased accuracy by refinement of the carbon multiplying factors and the correlation of a boron factor (B.F.) with carbon and alloy content. These refinements were based on analysis of thousands of heats of boron and non-boron 1500, 4100, 5000, and

8600 series steels encompassing a range of compositions as follows and a range of DI as contained in Tables 2-5 . The accuracy of this test method and the techniques used to develop it have been documented. For comparison of this test method to others, or for steel compositions outside the mentioned grades, the user should refer to other articles concerned with calculating hardenability.

Element Range, %

Carbon

Manganese

Silicon

Nickel

Chromium

Molybdenum

Copper

Vanadium

0.10–0.70

0.50–1.65

0.15–0.60

1.50 max

1.35 max

0.55 max

0.35 max

0.20 max

10.1.1 Calculated DI and Jominy hardenability curves are valid only within the chemical ranges stated above. However, to facilitate melting process control for higher alloy steels,

Hardenability Multiplying Factors have been included for calculating the DI within the following chemical composition ranges:

Element Range, %

Carbon

Manganese

Silicon

Nickel

Chromium

Molybdenum

Copper

Vanadium

Zirconium

0.01–0.90

0.01–1.95

0.01–2.00

0.01–3.50

0.01–2.50

0.01–0.55

0.01–0.55

0.01–0.20

0.01–0.25

10.2

Tables 2-18 are to be used to calculate hardenability from the chemical ideal diameter for the grades shown in

10.1

.



4


A255 − 10

FIG. 4 Facsimile of Standard ASTM Hardenability Chart, Showing Typical Hardenability Curves

[Chart Size: 8 1 ⁄

2 by 11 in. (216 by 279 mm)]

Hardenability results are to be reported for the first 10 sixteenth

(16 mm), the 12, 14, 16, 18, 20, 24, 28, and 32 sixteenths of an inch.

N OTE 5—The reporting of hardenability using the calculated method differs from the procedure as shown in

6.4.4

.

10.3

DI Calculation for Non-Boron Steels— This calculation relies on a series of hardenability factors ( Table 6 ) for each alloying element in the composition which, when multiplied together, gives a DI value. (For simplicity, only multiplying factors for DI in inch-pound units are given. For DI in millimetres, use the metric value table.) The effects of phosphorous and sulfur are not considered since they tend to cancel one another. A No. 7 austenitic grain size is assumed since most steels with hardenability control are melted to a fine-grain practice where experience has demonstrated that a high percentage of heats conform to this grain size. An example DI calculation is given as follows for an SAE 4118 modified steel:

Element % Multiplying Factor

Carbon 0.22

0.119

Element

Manganese

Silicon

Nickel

Chromium

Molybdenum

Copper

Vanadium where:

%

0.80

0.18

0.10

0.43

0.25

0.10

0.05

Multiplying Factor

3.667

1.126

1.036

1.929

1.75

1.04

1.09

DI = 0.119 × 3.667 × 1.126 × 1.036 × 1.929 × 1.75 × 1.04 × 1.09 = 1.95 in.

10.4

DI Calculation for Boron Steels— With an effective steel making process, the boron factor (signifying the contribution for boron to increased hardenability) is an inverse function of the carbon and alloy content. The higher the carbon or alloy content, or both, the lower the boron factor.

10.4.1 The actual boron factor is expressed by the following relationship:

B.F.

5 measured DI ~ from Jominy data and carbon content !

calculated DI ~ from composition excluding boron !

(1)

10.4.2 An example of actual boron factor determination is given as follows for an SAE 15B30 modified steel:



5


Composition,

% C

0.29

“J” Position ( 1 ⁄

8 in.)

Hardness, HRC

“J” Position ( 1 ⁄

8 in.)

Hardness, HRC

Mn

1.25

Si

0.20

Ni

0.13

Cr

0.07

End-Quench Test Results, in.

1 2 3 4

50

8

38

50

9

33

49

10

28

48

12

25

Calculated

DI

Mo Cu B

(boron excluded)

0.03

0.24

0.0015 1.35

in.

5

47

14

22

6

45

16

20

7

41

10.4.3 Using Table 7 , determine the nearest location on the end-quench curve where hardness corresponding to 50% martensite occurs for the actual carbon content. For the example heat with 0.29 carbon, this hardness is 37 HRC occurring at a

“J” distance of required).

8 ⁄

16 in. from the quenched end (interpolation

10.4.4 From Table 8 (in.), a “J” distance of 8 ⁄

16 in. equates to a measured DI of 2.97 in. (interpolation required).

Boron Factor 5

2.97 in.

1.35 in.

5 2.2 boron factor (2)

10.4.5

Calculation of DI with Boron (DI

B

):

10.4.5.1 Calculate the DI without boron. For the example in

10.4.4

, this DI is 1.35 in.

10.4.5.2 Calculate the alloy factor (the product of all the multiplying factors from Table 6 excluding carbon). For the example in

10.4.4

:

Alloy Factor 5

Calculated DI ~ without boron !

Carbon multiplying factor

5

1.35 in.

0.157 in.

5 8.6 (3)

10.4.5.3 Determine the boron multiplying factor from Table

10 . For this example with 0.29% carbon and an alloy factor of

8.6, the boron multiplying factor is 2.31 (interpolation required).

10.4.6 Calculate the DI with boron as follows: where:

DI

B

= DI (without boron) × boron factor

A255 − 10

DI

B

DI

B

= 1.35 in. × 2.31

= 3.12 in.

10.5

Hardenability Curves from Composition— With a predetermined DI (DI

B for boron steel), the end-quench hardenability curve can be computed by the following procedure:

10.5.1 The initial hardness (IH) at the J = 1 ⁄

16 in. position is a function of carbon content and independent of hardenability and is selected from Table 7 . For the example non-boron SAE

4118 modified heat containing 0.22 % carbon, the initial hardness is 45 HRC.

10.5.2 The hardness at other positions along the end-quench specimen (termed distance hardness) is determined by dividing the initial hardness by the appropriate factor from Table 2 (in.) or Table 3 (mm) for non-boron steels or from Table 4 (in.) or

Table 5 (mm) for boron steels.

10.6 For the example non-boron heat with an IH = 45 HRC and a calculated DI of 1.95 in., the hardness at the respective end-quench positions can be calculated by dividing 45 by the appropriate dividing factor listed in Table 2 (in.) for non-boron steels. (For simplicity, the DI should be rounded to the nearest

0.1 in.).

10.7 Distance Dividing Hardness Factors in Tables 2-5 are calculated from the equations in Tables 15-18 . Multiplying

Factors in Table 6 are calculated from the equations in Table

11 . Jominy Distance for 50 % Martensite versus DI in Tables 8 and 9 are calculated from the equations in Table 13 . Boron

Factor versus % Carbon and Alloy Factor in Table 10 are calculated from the equations in Table 14 . Equations representing a least squares polynomial fit of the data contained in Table

7 is listed in Table 12 . The use of these equations to plot curves may result in random inflection points due to the characteristics of polynomial equations. These inflections will be minor, however, and should be disregarded.

11. Keywords

11.1 end-quench hardenability; hardenability



6





Laboratory Experiment IV

CONCRETE MIX DESIGN BY A TRIAL BATCH METHOD

1 OBJECTIVES

1.

Verify the effectiveness of mix proportioning using the Trial Batch Method.

2.

Prepare six 3x6 cylinder concrete specimens for later evaluation of compressive and splitting tensile strengths.

3.

Prepare data sheets and experimental notes that reflect the basic logic of the trial batch method. Perform the experiment in a professional manner and report the results in a clear and concise way.

2 MATERIALS AND EQUIPMENT

1.

3 dry material containers

2.

1 wet material container

3.

Dry mix scoop

4.

Mixing pan

5.

2 mixing spatulas

6.

Wet mix scoop

7.

Slump cone and base

8.

5/8” and 1/4” Rods

9.

12” ruler

10.

Unit weight steel container (0.2 cu ft)

11.

Steel plate

12.

Small steel trowel

13.

Plastic mallet

14.

6 plastic 3x6 in. molds

15.

Cleaning brush

3 ORGANIZATION

The physical characteristics of the materials which will be used in this experiment are shown in Table 1. The students in the laboratory will be divided into parties of four or five persons.

Each group will be responsible for one mix design, as shown in Table 2, where the weights of cement and water as well as the slump for each mix are given.

TABLE 1 - THE PHYSICAL CHARACTERISTICS OF THE STOCKED MATERIALS

Cement Fine Aggregate (FA) Coarse Aggregate (CA)

Source

Specific Gravity

Fineness Modulus

Dry Rodded Unit Weight

Moisture Content

1

.

Quikrete Type II-V

Cement

3.15

Note 1 – Moisture content will be announced in class

Vulcan Sand

2.66

2.9

Madison 3/8” Pea

Gravel

2.67

103 pcf




This is a simple empirical approach to mix design. It is a two step process. First you select an appropriate w/c ratio for the strength or durability required, and then you make a small trial mix with the selected w/c ratio to obtain the desired wet consistency (i.e., slump & workability). In practice, it often proves useful to make several trial batches to achieve the most economical mix with the desired properties, but in this laboratory experiment that will not be necessary.

TABLE 2 - WEIGHTS OF CEMENT AND WATER FOR EACH GROUP

Group Number Weight of Cement for

Trial Mix (lb) (

Slump

± ½ in.)

Amount of Water for

Trial Mix (lb)

4

5

6

1

2

3

8.00

7.50

7.00

6.50

6.00

5.00

3

3

3

3

3

3

3.20

3.75

3.85

3.90

3.90

3.50

1.

Each group will make a trial batch of concrete as follows: i.) Weigh out the exact amount of cement as given in Table 2. ii.) Weigh out the exact amount of water as given in Table 2. iii.) Weigh out 30 pounds of both CA and FA including the weight of the bucket. iv.) Place a few scoops of FA in the dampened mixing pan, then blend all of the cement with the small amount of FA in the mixing pan until they are thoroughly blended. v.) Add several scoops of CA to the dry materials in the mixing pan and then blend the dry mix until the CA are uniformly distributed throughout the batch. vi.) Mix all of the water with the dry materials in the mixing pan, and then begin to add small quantities of CA and FA to reduce the slump.

2.

When the workability appears near the desired slump, perform the slump test. The slump cone is filled in three lifts which are each rodded 25 times. One person should hold down the slump cone until it is time to lift it. Then another person should pull the cone straight up. Make two slump tests in order to explore the accuracy of this measurement, and if they differ by more than l in., make a third measurement and take an average between the two slumps.

3.

IF the slump is more than ½ in. (measured to the nearest ¼ in.) over the desired slump, THEN some aggregate should be added to the trial batch to obtain the desired slump. ON THE OTHER HAND , IF the slump is less than the desired slump,

(taking into account the expected accuracy of the method of ± ½ in. measured to the nearest ¼ in.), THEN add a small amount of cement and water in the correct W/C ratio and repeat step (4).

4.

IF the slump is within ±

THEN :

½ in. (measured to the nearest ¼ in.) of the desired slump, i.) Measure and record slump, cohesiveness, trowelling workability of the fresh concrete. ii.) Weigh the unused amounts of CA and FA and record the weights used in the trial batch on the data sheet.


Department of Civil and Environment Engineering iii.) Then measure the unit weight of the concrete using the container provided.

Note that you will have to have the empty weight and the volume of this container in order to complete the calculation. The unit weight container is filled in three lifts which are each rodded 25 times just as the slump cone is filled. It is also helpful to tap the sides of the container with the rubber mallet several times after each lift has been rodded. After the final lift has been consolidated, the top surface concrete is leveled off as cleanly as possible to be parallel with the edge of the container. Clean the outside of the container before the weight is taken. iv.) Cast three 3x6 in. cylinders for later determination of f ’ c

,

5.

Each student is expected to complete the Laboratory Data Sheet for this experiment before he or she leaves the laboratory. In completing this Data Sheet assume that the cement costs $95/ton, the water $0.20/ton, the CA $8.00/ton and the FA $9.50/ton.

You will note that in the last column you estimate the cost per ton for the final mix.

The relationship between strength and water-to-cement ratio is given in Table 3.

TABLE 3 - RELATIONSHIP BETWEEN WATER/CEMENT RATIO AND

COMPRESSIVE STRENGTH OF CONCRETE

Compressive strength at 28 days, (psi)

6000

5000

4000

3000

2000

Water/cement ratio, by weight

Non-air entrained concrete

0.41

0.48

0.57

0.68

0.82

Water/cement ratio, by weight

Air-entrained concrete

----

0.40

0.48

0.59

0.74

5 REPORT

The report for this laboratory will not be due until after the mechanical tests have been completed. The tests will be performed 28 days after casting. Each student will be responsible for submitting a report on this experiment which reflects an understanding of the proportioning method. Each laboratory report will contain the following:

1.

A summary of the procedures followed by the group, which includes an explanation of how the data (e.g. cement content, w/c ratios and amounts of fine aggregate and coarse aggregate) was obtained. It is particularly important to calculate the actual w/c taking into account the free water in the fine and coarse aggregate.

2.

A copy of the completed concrete mix worksheet.

3.

A description of preparation and testing of concrete specimens. Note the strength of the individual specimens as well as the average. Compare the measured strength with the strength listed in Table 3.

4.

A calculation of the costs of the Trial Batch mix

In addition, each student is expected to perform the experiment in a professional manner and report the results in a clear and concise way. Each student is to prepare his or her own report.

It is permissible for students to work together, but each report should be unique.




Laboratory Experiment IV

CONCRETE MIX DESIGN BY A TRIAL BATCH METHOD

NAME:____________________________

GRADE SHEET

1.


2.

Summary of procedure followed by group ____

3.

Completion of concrete mix worksheet

(1) ______

(2) ______

4.

Description of preparation and testing of concrete specimens with special attention to notation of actual water-to-cement ratios

5.

Calculations of the costs of the Trial Batch mix

6.

Discussion of strength compared to Table 3

TOTAL

(4) ______

(1) ______

(1) ______

(10) ______




Laboratory Experiment IV

CONCRETE MIX DESIGN BY A TRIAL BATCH METHOD

Date: Name:

Lab Partners:

CHARACTERISTICS OF COARSE AGGREGATE

Type Used:

Bulk Specific Gravity:

Density (lbs / cu ft):

Absorption Capacity (%):

Moisture Content (%):

Free Mositure (%):

Cost ($ / ton):

CHARACTERISTICS OF CEMENT

Type Used:



Cost ($ / ton):

Madison Pea Gravel

2.69

167.9

1.2

$8.00

Quikrete Cement Type II/V

3.15

196.6

$95.00

CHARACTERISTICS OF FINE AGGREGATE

Type Used:





Free Mositure (%):

Cost ($ / ton):

CHARACTERISTICS OF WATER


Density of Water (lbs / cu ft)

Cost ($ / ton):

TRIAL BATCH SPECIFICATIONS:

SLUMP

APPROX. WATER-‐TO-‐CEMENT RATIO (by wt): in.

decimal (Not including water in Fine and Coarse Aggregate.)

Vulcan Sand

2.65

165.4

1.6

$9.50

1

62.4

$0.20

Add'l or Used Amount, lbs Total Amount, lbs Materials

CEMENT

WATER

FINE AGG

COARSE AGG

Starting Amount, lbs

FRESH PROPERTIES:

MEASURED SLUMP

VOL. OF CONTAINER:

WT OF CONTAINER:

WT OF CONTAINER + CONCRETE:

WT OF CONCRETE:

Materials

Actual Trial Mix

Total Amount, lbs

CEMENT

WATER

FINE AGG

COARSE AGG

Total

0.2

%

-‐-‐-‐-‐-‐-‐-‐-‐-‐

-‐-‐-‐-‐-‐-‐-‐-‐-‐ in.

cu ft lbs lbs lbs

Free Moisture Correction

<-‐-‐-‐-‐-‐-‐EQUAL-‐-‐-‐-‐-‐-‐> lbs

-‐-‐-‐-‐-‐-‐-‐-‐-‐

COHESIVENESS (Circle One):

High / Normal / Low

TROWELING WORKABILITY (Circle One):

High / Normal / Low

Saturated-‐Surface Dry Mix lbs

Materials

CEMENT

WATER

FINE AGG

COARSE AGG

Total

Precentage, % (by wt)

CALCULATED VALUES

UNIT WEIGHT OF CONCRETE:

UNIT WEIGHT OF CONCRETE:

ACTUAL WATER-‐TO-‐CEMENT RATIO (by wt):

AIR CONTENT (by vol.):

ESTIMATED COMPRESSIVE STRENGTH:

Mix Proportions (SSD Basis) lbs / cu yd Density, lbs / cu ft

196.6

62.4

-‐-‐-‐-‐-‐-‐-‐-‐-‐ lbs / cu ft lbs / cu yd decimal

% psi cu ft / cu yd $ / cu yd

CONVERSIONS

27 cu ft = 1 cu yd

2000 lbs = 1 ton

THIS SHEET IS TO BE COMPLETED BEFORE LEAVING THE LABORATORY Checked by:________________________________




Laboratory Experiment V

CONCRETE MIX DESIGN BY ACI METHOD

1 OBJECTIVES

1.

Verify the effectiveness of the ACI Batch Method for Mix Proportioning (See ACI

211.1 and Ch. 9 in textbook).

2.

Prepare six 3x6 in. cylindrical specimens for evaluation of 28-day compressive.

3.

Prepare data sheets and experimental notes that reflect the basic logic of the ACI batch method.

4.

Perform the experiment in a professional manner and report the results in a clear and concise way.

2 MATERIALS AND EQUIPMENT

1.

3 dry material containers

2.

1 wet material container

3.

Dry mix scoop

4.

Mixing pan

5.

2 mixing spatulas

6.

Wet mix scoop

7.

Slump cone and base

8.

5/8” and 1/4” Rods

9.

12” ruler

10.

Unit weight steel container (0.2 cu ft)

11.

Steel plate

12.

Small steel trowel

13.

Plastic mallet

14.

6 plastic 3x6 in. molds

15.

Cleaning brush

3 ORGANIZATION

The physical characteristics of the materials that will be used in this experiment along with the data sheets are shown in Appendix A. The students in the laboratory will stay in the groups established in Laboratory IV. Each group will be responsible for two mix designs, as shown in Table 1, where the 28-day compressive strengths and slumps for each mix are given. Assume no air entrainment.



Table 1 – 28-day Compressive Strengths & Slumps for Each Group

Mix 1 Mix 2

Group No.

1

2

3

4

5

6

28-day

Compressive

Strength (f’c), psi

6000

3000

3500

4000

5000

5500

Slump, in. (+/-

½ in.)

3

3

3

3

3

3

28-day

Compressive

Strength (f’c),

* This concrete will be cured at 50% RH instead of 100% RH. psi

3000

6000

5000

5000*

4000

3000

Slump, in. (+/-

½ in.)

1-1/2

1-1/2

1-1/2

1-1/2

1-1/2

1-1/2

4 PROCEDURES

1.

Each person will calculate the SSD mix proportions for both Mix 1 and Mix 2 assigned to his/her group in Table 1 using the ACI method. THESE

CALCULATIONS SHOULD BE DONE BEFORE COMING TO THE LAB

SESSION. The calculations should be performed using the first data sheet found in

Appendix A.

2.

Each group will compare the individual calculations of its team members and prepare the second data sheet during the lab session. The second data sheet should provide the batch amounts of cement, Water, fine aggregate and coarse aggregate that will be use for a 0.01 cu. yd of concrete. These weights will be corrected for moisture in the aggregates before mixing. Each group will bring its final mix designs to the instructor for approval before mixing.

3.

Once the group has approval, they will first make a 0.01 cu. yd. batch of Mix 1.

During mixing, the group will retain 5% of the mix water in order to help in adjusting the slump.

4.

Measure the slump.

5.

IF the slump is less than the desired slump (± 1/2 in.), THEN some of the water that was retained should be added to the mix, but IF the slump is more than the desired slump (± 1/2 in.), THEN fine aggregate should be added to the trial batch to obtain the desired slump.

6.

IF the slump is within ± 1/2 in. (measured to the nearest 1/4”) of the desired slump,

THEN a.

Record the slump, and qualitatively evaluate the cohesiveness and trowelling workability of the fresh concrete. b.

Measure the unit weight of the concrete. c.

Cast six 3x6 in. cylinders for later determination of compressive and splitting tensile strengths.

7.

Each group will follow the same procedure from the first mix to batch and cast Mix

2, as shown in Table I.



5 REPORT

The report for this laboratory will not be due until after the mechanical tests have been completed. These tests are scheduled 28 days after hydration as begun. Each student will be responsible for submitting a report on this experiment that reflects an understanding of the

ACI method for proportioning concrete. Each laboratory report will contain the following:

1.

A summary of the experimental procedure followed by the group. This includes a preparation of data sheets and experimental notes that reflect the basic logic of the

ACI method.

2.

Summary of the calculations performed on the third and fourth data sheets in

Appendix A.

3.

Verification of the effectiveness when using the ACI Method for mix proportioning.

This should include a comparison of the calculated ACI mix proportions (at SSD) with the total proportions used after mixing (at SSD).

4.

Description of preparation and testing of concrete specimens with special attention to the water-to-cement ratios.

5.

Calculations of the cost per ton for each mix based on the unit cost provided on the first data sheet in Appendix A. A discussion on the cost differences between the two mixes.

In addition, each student is expected to perform the experiment in a professional manner and report the results in a clear and concise way. Each student is to prepare his/her own report. It is permissible for students to work together, but each report should be unique and the work product of one student.




Laboratory Experiment V

CONCRETE MIX DESIGN BY ACI BATCH METHOD

NAME:____________________________

GRADE SHEET

1.


2.

Summary of procedure followed by group ____

3.

Completion of concrete mix worksheet

(1) ______

(1) ______

4.

Comparison of the ACI calculated mixes with the actual proportions

5.

Description of preparation and testing of concrete specimens with special attention to actual water-to-cement ratios

6.

Calculations of the costs of the two ACI mixes

7.

Discussion of strength compared to Table 9-3 in Concrete: Microstructure, Properties, and Materials by Mehta and Monteiro

TOTAL

(2) ______

(2) ______

(2) ______

(1) ______

(10) ______



Name:


Laboratory Experiment V

CONCRETE MIX DESIGN BY ACI METHOD

Date:

Lab Partners:

CHARACTERISTICS OF COARSE AGGREGATE

Type Used:

Nominal Max. Size Aggregate



Dry-‐Rodded Unit Wt. (lbs / cu ft):



Madison Pea Gravel

3/8 in.

2.69

103.0

1.2

Free Mositure (%):

Cost ($ / ton): $8.00

CHARACTERISTICS OF FINE AGGREGATE

Type Used:



Fineness Modulus:



Free Mositure (%):

Cost ($ / ton):

Vulcan Sand

2.65

3.0

1.6

$9.50

CHARACTERISTICS OF WATER



Cost ($ / ton):

1

62.4

$0.20

CHARACTERISTICS OF CEMENT

Type Used:



Cost ($ / ton):

Quickrete Type II/V

3.15

$95.00

SPECIFICATIONS

Slump (in.):

Mix 1

Compressive Strength (psi):

Air entrainment: yes / no

Exposure Condition (If applicable): mild / moderate / severe

ACI MIX DESIGN

1. From Table 9.2: air (%, by vol.):

2. From Table 9.2: Water (lbs / cu yd):

3. From Table 9.3: w/c (by wt)

4. Calculate: Cement (lbs / cu yd)

5. From Table 9.5: CA / Total (by vol.)

6. Calculate: Coarse Agregate

(cu ft / cu yd)

(lbs / cu yd)

7. Calculate: Absolute Vol. (cu ft / cu yd)

CEMENT

WATER

COARSE AGG

AIR

TOTAL

8. Calculate: Fine Aggregate

(cu ft / cu yd)

(lbs / cu yd)

Mix 2 yes / no mild / moderate / severe



Name:




Date:

Mix 1

Material

CEMENT

WATER

FINE AGG

COARSE AGG

Total

Batch weights for 0.01 cu yd

SSD Weight lbs

Moisture Correction

Free Moisture, % lbs

<-‐-‐-‐-‐-‐-‐EQUAL-‐-‐-‐-‐-‐-‐>

Batch Weight lbs

Mix 2

Material

CEMENT

WATER

FINE AGG

COARSE AGG

Total

Batch weights for 0.01 cu yd

SSD Weight lbs

Moisture Correction

Free Moisture, % lbs

<-‐-‐-‐-‐-‐-‐EQUAL-‐-‐-‐-‐-‐-‐>

Batch Weight lbs






Date: Name:

Lab Partners:

Group Number:

FRESH PROPERTIES:

MEASURED SLUMP

VOL. OF CONTAINER:

WT OF CONTAINER:


WT OF CONCRETE:

WATER

Materials

CEMENT

FINE AGG

COARSE AGG

Total

Mix Number: in.

cu ft lbs lbs lbs


High / Normal / Low


High / Normal / Low

Weights for 0.01 cy yd concrete

Additional Amounts Added during Mixing

Batch Weight Added Amounts Total Weight lbs lbs lbs

Moisture Correction

Free Moisture, %

-‐

-‐ lbs

-‐

Corrected Mix

(SSD Basis) lbs

<-‐-‐-‐-‐-‐-‐EQUAL-‐-‐-‐-‐-‐-‐>

Corrected Mix Proportions (SSD Basis)

Percent

%, by wt.

lbs / cu yd Materials

CEMENT

WATER

FINE AGG

COARSE AGG

Total

CALCULATED VALUES

UNIT WEIGHT (DENSITY) OF CONCRETE:



ACTUAL AIR CONTENT (by vol.):

Density lbs / cu ft lbs / cu ft lbs / cu yd decimal

% cu ft / cu yd $ / cu yd

CONVERSIONS

27 cu ft = 1 cu yd

2000 lbs = 1 ton







Date: Name:

Lab Partners:

Group Number:

FRESH PROPERTIES:

MEASURED SLUMP

VOL. OF CONTAINER:

WT OF CONTAINER:


WT OF CONCRETE:

WATER

Materials

CEMENT

FINE AGG

COARSE AGG

Total

Mix Number: in.

cu ft lbs lbs lbs


High / Normal / Low


High / Normal / Low

Weights for 0.01 cy yd concrete

Additional Amounts Added during Mixing

Batch Weight Added Amounts Total Weight lbs lbs lbs

Moisture Correction

Free Moisture, %

-‐

-‐ lbs

-‐

Corrected Mix

(SSD Basis) lbs

<-‐-‐-‐-‐-‐-‐EQUAL-‐-‐-‐-‐-‐-‐>

Corrected Mix Proportions (SSD Basis)

Percent

%, by wt.

lbs / cu yd Materials

CEMENT

WATER

FINE AGG

COARSE AGG

Total

CALCULATED VALUES




ACTUAL AIR CONTENT (by vol.):

Density lbs / cu ft lbs / cu ft lbs / cu yd decimal

% cu ft / cu yd $ / cu yd

CONVERSIONS

27 cu ft = 1 cu yd

2000 lbs = 1 ton





Laboratory Experiment VI

MECHANICAL PROPOERTIES OF CONCRETE

1 OBJECTIVES

1.

Learn about experimental procedures used to determine the compressive strength, splitting tensile strength, modulus of elasticity and Poisson's Ratio for hardened concrete.

2.

Witness experiments which show the effects of changing the rate of loading on modulus of elasticity and the effects of sustained loading on the creep of concrete.

3.

Reduce and analyze experimental data, report on the strength and elastic properties of concrete, and prepare stress vs. strain curves for each concrete mix.

Each student will leave the laboratory period with his/her own set of data and will prepare a short report to be handed in one week later.

2 SAFETY

This experiment has the potential for a heavy concrete cylinder to fall on an individuals’ foot or debris from the compression test to hit an individual in the eye. All students are required to wear safety glasses and closed-toe shoes.

3 BACKGROUND

Two separate concrete mixes are to be evaluated in this experiment. They have been proportioned for two levels of strength; 3,000 psi and 6,000 psi strengths. A number of 6" x

12" concrete test cylinders were casted for each mix and these have been cured in a "fog chamber" for 28 days.

There are many ways to evaluate the mechanical properties of concrete, but there are certain

"standardized" test methods which we will use in this laboratory. They are the following

ASTM test procedures (Edited versions of these tests are included with this laboratory handout):

ASTM C 39 Compressive Strength of Cylindrical Concrete Specimens

ASTM C 469 Static Modulus of Elasticity and Poisson's Ratio of Concrete in

Compression

ASTM C 496 Splitting Tensile Strength of Cylindrical Concrete Specimens

In practice, some engineers will estimate the elastic modulus of concrete using the following equation, which is found in ACI 318.



E c

= w 1 .

5 c

33 f c

' f w

’ c c

= Unit weight of the concrete, pcf

= 28-day compressive strength, psi

This equation is considered valid when the concrete has a unit weight between 90 and 160 pcf. The unit weights for each mix will be given in the laboratory.

The splitting tensile test is one of the most effective ways to measure the tensile strength of a brittle material. In this test a concrete cylinder, of the same type used for compression tests, is placed with its long axis horizontal between the platens of a testing machine. The load is increased until failure when splitting along the vertical diameter takes place. A schematic diagram of how this test is performed is shown in Fig. 3-16 in the concrete textbook on page

73. The test is described on page 72 and the equation for the tensile stress is given there, as well as in ASTM C 496. Note, as a "rule of thumb", the tensile strength is approximately 8 to

9 percent of the compressive strength for moderate-strength concrete.


For each concrete mix the sequence for testing will be as follows:

1.

Compression Test: a.

Follow ASTM C 39 to obtain the f', for each concrete b.

Follow ASTM C 469 to obtain the static elastic modulus and Poisson ratio for the concrete. Note that the first step in ASTM C 469 is to obtain f', by ASTM

C 39. c.

The effects of multiple load cycles will be demonstrated, if possible.

2.

Splitting Tensile Test: a.

Test two 6" x 12" cylinders from each mix according to ASTM C 496. b.

Analyze the fracture surface of each specimen to determine the percentage of coarse aggregate fractured as opposed to debonding.

5 REDUCTION OF DATA

The data for this experiment will be available after completion of the lab. The stress strain curves for both Mix 1 and Mix 2 will be shown on graphs labeled "Concrete Stress Strain

Curves." The maximum load for both the compression and splitting tensile tests will be given on another data sheet.

The second and third "modulus" loading cycles for each mix will be shown on a graph labeled "Modulus of Elasticity Curves for Mixes 1 & 2," and these will be used to determine the elastic modulus.

From the data sheets and graphs determine the following quantities for each mix:

1.

Compressive Strength, f ' c

2.

Modulus of Elasticity, using chord method per ASTM C 469



From the splitting tensile tests determine the following quantities for each mix:

1.

Tensile Strength

2.

Make a qualitative estimate from broken surface samples of how many of the largest pieces of coarse aggregate are broken for each mix.

6 REPORT

1.

Label the f ’ c on the stress vs. strain curves for both of the mixes on the graph labeled

"Concrete Stress Strain Curves."

2.

Present all the data described in Section 5 Reduction of Data above.

3.

Compare the compressive strength values for each mix with the expected values from

Table 9-3 in the concrete textbook. The final w/c for Mix 1 and Mix 2 will be given on the data sheet.

4.

How does the measured elastic modulus for each mix compare to that calculated from the equation used in the ACI Building Code 318.

5.

Compare the tensile strengths with the compressive strength values for the mixes and determine how closely it matches the "rule of thumb" that the tensile strength is 10% of the compressive strength.

6.

From the fractured specimens after the splitting tension test, give a qualitative estimated proportion of coarse aggregate fractured during the splitting tension tests of the two mixes and discuss the relative strength of the paste for the mixes. The fracture surface of each specimen can be divided into four equal quarter sections, and the broken and unbroken pieces of aggregate showing in each quarter counted.

7.

From a careful analysis of the fracture surface it may be possible to determine which end of a splitting tensile specimen was the top during casting. Explain what to look for and describe if you can see indications of this on the test specimens.




Laboratory Experiment VI

MECHANICAL PROPOERTIES OF CONCRETE

NAME:____________________________

GRADE SHEET

1.


2.

Determination of Compressive Strength from graphs for Mix 1 and 2 (2) ______

3.

4.

Determination of Modulus of Elasticity from graphs for Mix 1 and 2

Determination of Poisson’s ratio for Mix 1

5.

Calculation of the average tensile strength for each mix

6.

Comparison of the tensile strength with the compression strengths

TOTAL

(4) ______

(1) ______

(2) ______

(2) ______

(12) ______

Designation: C39/C39M − 12a

Standard Test Method for

Compressive Strength of Cylindrical Concrete Specimens

1

This standard is issued under the fixed designation C39/C39M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ´ ) indicates an editorial change since the last revision or reapproval.


1. Scope*

1.1 This test method covers determination of compressive strength of cylindrical concrete specimens such as molded cylinders and drilled cores. It is limited to concrete having a density in excess of 800 kg/m

3

[50 lb/ft

3

].

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The inch-pound units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.3


( Warning —Means should be provided to contain concrete fragments during sudden rupture of specimens. Tendency for sudden rupture increases with increasing concrete strength and it is more likely when the testing machine is relatively flexible. The safety precautions given in the

Manual of Aggregate and Concrete

Testing

are recommended.)

1.4 The text of this standard references notes which provide explanatory material. These notes shall not be considered as requirements of the standard.


2.1

ASTM Standards:

2

C31/C31M

Practice for Making and Curing Concrete Test

Specimens in the Field

C42/C42M

Test Method for Obtaining and Testing Drilled

Cores and Sawed Beams of Concrete

1 This test method is under the jurisdiction of ASTM Committee C09 on

Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee

C09.61

on Testing for Strength.

Current edition approved Sept. 1, 2012. Published October 2012. Originally approved in 1921. Last previous edition approved in 2012 as C39/C39M–12. DOI:

10.1520/C0039_C0039M-12a.



C192/C192M


Specimens in the Laboratory

C617

Practice for Capping Cylindrical Concrete Specimens

C670

Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials

C873

Test Method for Compressive Strength of Concrete

Cylinders Cast in Place in Cylindrical Molds

C1077

Practice for Agencies Testing Concrete and Concrete

Aggregates for Use in Construction and Criteria for

Testing Agency Evaluation

C1231/C1231M

Practice for Use of Unbonded Caps in

Determination of Compressive Strength of Hardened Concrete Cylinders

E4

Practices for Force Verification of Testing Machines

E74

Practice of Calibration of Force-Measuring Instruments for Verifying the Force Indication of Testing Machines

Manual of Aggregate and Concrete Testing

3. Summary of Test Method

3.1 This test method consists of applying a compressive axial load to molded cylinders or cores at a rate which is within a prescribed range until failure occurs. The compressive strength of the specimen is calculated by dividing the maximum load attained during the test by the cross-sectional area of the specimen.

4. Significance and Use

4.1 Care must be exercised in the interpretation of the significance of compressive strength determinations by this test method since strength is not a fundamental or intrinsic property of concrete made from given materials. Values obtained will depend on the size and shape of the specimen, batching, mixing procedures, the methods of sampling, molding, and fabrication and the age, temperature, and moisture conditions during curing.

4.2 This test method is used to determine compressive strength of cylindrical specimens prepared and cured in accordance with Practices

C31/C31M , C192/C192M ,

C617 , and

C1231/C1231M

and Test Methods

C42/C42M

and

C873 .

4.3 The results of this test method are used as a basis for quality control of concrete proportioning, mixing, and placing



Copyright by ASTM Int'l (all rights reserved); Thu Dec 19 11:27:04 EST 2013


1


C39/C39M − 12a operations; determination of compliance with specifications; control for evaluating effectiveness of admixtures; and similar uses.

4.4 The individual who tests concrete cylinders for acceptance testing shall meet the concrete laboratory technician requirements of Practice

C1077 , including an examination

requiring performance demonstration that is evaluated by an independent examiner.

N OTE 1—Certification equivalent to the minimum guidelines for ACI

Concrete Laboratory Technician, Level I or ACI Concrete Strength

Testing Technician will satisfy this requirement.

5. Apparatus

5.1

Testing Machine— The testing machine shall be of a type having sufficient capacity and capable of providing the rates of loading prescribed in

7.5

.

5.1.1 Verify calibration of the testing machines in accordance with Practices

E4 , except that the verified loading range

shall be as required in

5.3

. Verification is required:

5.1.1.1 Within 13 months of the last calibration,

5.1.1.2 On original installation or immediately after relocation,

5.1.1.3 Immediately after making repairs or adjustments that affect the operation of the force applying system or the values displayed on the load indicating system, except for zero adjustments that compensate for the mass of bearing blocks or specimen, or both, or

5.1.1.4 Whenever there is reason to suspect the accuracy of the indicated loads.

5.1.2

Design— The design of the machine must include the following features:

5.1.2.1 The machine must be power operated and must apply the load continuously rather than intermittently, and without shock. If it has only one loading rate (meeting the requirements of

7.5

), it must be provided with a supplemental

means for loading at a rate suitable for verification. This supplemental means of loading may be power or hand operated.

5.1.2.2 The space provided for test specimens shall be large enough to accommodate, in a readable position, an elastic calibration device which is of sufficient capacity to cover the potential loading range of the testing machine and which complies with the requirements of Practice

E74 .

N

OTE

2—The types of elastic calibration devices most generally available and most commonly used for this purpose are the circular proving ring or load cell.

5.1.3

Accuracy— The accuracy of the testing machine shall be in accordance with the following provisions:

5.1.3.1 The percentage of error for the loads within the proposed range of use of the testing machine shall not exceed

6 1.0 % of the indicated load.

5.1.3.2 The accuracy of the testing machine shall be verified by applying five test loads in four approximately equal increments in ascending order. The difference between any two successive test loads shall not exceed one third of the difference between the maximum and minimum test loads.

5.1.3.3 The test load as indicated by the testing machine and the applied load computed from the readings of the verification device shall be recorded at each test point. Calculate the error,

E, and the percentage of error, E p

, for each point from these data as follows:

E 5 A 2 B (1)

E p

5 100 ~ A 2 B !

/ B where:

A = load, kN [lbf] indicated by the machine being verified, and

B = applied load, kN [lbf] as determined by the calibrating device.

5.1.3.4 The report on the verification of a testing machine shall state within what loading range it was found to conform to specification requirements rather than reporting a blanket acceptance or rejection. In no case shall the loading range be stated as including loads below the value which is 100 times the smallest change of load estimable on the load-indicating mechanism of the testing machine or loads within that portion of the range below 10 % of the maximum range capacity.

5.1.3.5 In no case shall the loading range be stated as including loads outside the range of loads applied during the verification test.

5.1.3.6 The indicated load of a testing machine shall not be corrected either by calculation or by the use of a calibration diagram to obtain values within the required permissible variation.

5.2 The testing machine shall be equipped with two steel

bearing blocks with hardened faces ( Note 3 ), one of which is a

spherically seated block that will bear on the upper surface of the specimen, and the other a solid block on which the specimen shall rest. Bearing faces of the blocks shall have a minimum dimension at least 3 % greater than the diameter of the specimen to be tested. Except for the concentric circles described below, the bearing faces shall not depart from a plane by more than 0.02 mm [0.001 in.] in any 150 mm [6 in.] of blocks 150 mm [6 in.] in diameter or larger, or by more than

0.02 mm [0.001 in.] in the diameter of any smaller block; and new blocks shall be manufactured within one half of this tolerance. When the diameter of the bearing face of the spherically seated block exceeds the diameter of the specimen by more than 13 mm [0.5 in.], concentric circles not more than

0.8 mm [0.03 in.] deep and not more than 1 mm [0.04 in.] wide shall be inscribed to facilitate proper centering.

N

OTE

3—It is desirable that the bearing faces of blocks used for compression testing of concrete have a Rockwell hardness of not less than

55 HRC.

5.2.1 Bottom bearing blocks shall conform to the following requirements:

5.2.1.1 The bottom bearing block is specified for the purpose of providing a readily machinable surface for mainte-

nance of the specified surface conditions ( Note 4 ). The top and

bottom surfaces shall be parallel to each other. If the testing machine is so designed that the platen itself is readily maintained in the specified surface condition, a bottom block is not required. Its least horizontal dimension shall be at least 3 %



2


C39/C39M − 12a greater than the diameter of the specimen to be tested.

Concentric circles as described in

5.2

are optional on the bottom block.

N

OTE

4—The block may be fastened to the platen of the testing machine.

5.2.1.2 Final centering must be made with reference to the upper spherical block. When the lower bearing block is used to assist in centering the specimen, the center of the concentric rings, when provided, or the center of the block itself must be directly below the center of the spherical head. Provision shall be made on the platen of the machine to assure such a position.

5.2.1.3 The bottom bearing block shall be at least 25 mm [1 in.] thick when new, and at least 22.5 mm [0.9 in.] thick after any resurfacing operations.

5.2.2 The spherically seated bearing block shall conform to the following requirements:

5.2.2.1 The maximum diameter of the bearing face of the suspended spherically seated block shall not exceed the values given below:

Diameter of

Test Specimens, mm [in.]

Maximum Diameter of Bearing Face, mm [in.]

50 [2]

75 [3]

100 [4]

150 [6]

200 [8]

105 [4]

130 [5]

165 [6.5]

255 [10]

280 [11]

N

OTE

5—Square bearing faces are permissible, provided the diameter of the largest possible inscribed circle does not exceed the above diameter.

5.2.2.2 The center of the sphere shall coincide with the surface of the bearing face within a tolerance of 6 5 % of the radius of the sphere. The diameter of the sphere shall be at least

75 % of the diameter of the specimen to be tested.

5.2.2.3 The ball and the socket shall be designed so that the steel in the contact area does not permanently deform when loaded to the capacity of the testing machine.

N

OTE

6—The preferred contact area is in the form of a ring (described as “preferred bearing area”) as shown on

Fig. 1 .

N

OTE

1—Provision shall be made for holding the ball in the socket and for holding the entire unit in the testing machine.

FIG. 1 Schematic Sketch of a Typical Spherical Bearing Block

5.2.2.4 At least every six months, or as specified by the manufacturer of the testing machine, clean and lubricate the curved surfaces of the socket and of the spherical portion of the machine. The lubricant shall be a petroleum-type oil such as conventional motor oil or as specified by the manufacturer of the testing machine.

N

OTE

7—To ensure uniform seating, the spherically seated head is designed to tilt freely as it comes into contact with the top of the specimen.

After contact, further rotation is undesirable. Friction between the socket and the spherical portion of the head provides restraint against further rotation during loading. Petroleum-type oil such as conventional motor oil has been shown to permit the necessary friction to develop. Pressure-type greases can reduce the desired friction and permit undesired rotation of the spherical head and should not be used unless recommended by the manufacturer of the testing machine.

5.2.2.5 If the radius of the sphere is smaller than the radius of the largest specimen to be tested, the portion of the bearing face extending beyond the sphere shall have a thickness not less than the difference between the radius of the sphere and radius of the specimen. The least dimension of the bearing face shall be at least as great as the diameter of the sphere (see

Fig.

1 ).

5.2.2.6 The movable portion of the bearing block shall be held closely in the spherical seat, but the design shall be such that the bearing face can be rotated freely and tilted at least 4° in any direction.

5.2.2.7 If the ball portion of the upper bearing block is a two-piece design composed of a spherical portion and a bearing plate, a mechanical means shall be provided to ensure that the spherical portion is fixed and centered on the bearing plate.

5.3

Load Indication:

5.3.1 If the load of a compression machine used in concrete testing is registered on a dial, the dial shall be provided with a graduated scale that is readable to at least the nearest 0.1 % of

the full scale load ( Note 8 ). The dial shall be readable within

1 % of the indicated load at any given load level within the loading range. In no case shall the loading range of a dial be considered to include loads below the value that is 100 times the smallest change of load that can be read on the scale. The scale shall be provided with a graduation line equal to zero and so numbered. The dial pointer shall be of sufficient length to reach the graduation marks; the width of the end of the pointer shall not exceed the clear distance between the smallest graduations. Each dial shall be equipped with a zero adjustment located outside the dialcase and easily accessible from the front of the machine while observing the zero mark and dial pointer. Each dial shall be equipped with a suitable device that at all times, until reset, will indicate to within 1 % accuracy the maximum load applied to the specimen.

N OTE 8—Readability is considered to be 0.5 mm [0.02 in.] along the arc described by the end of the pointer. Also, one half of a scale interval is readable with reasonable certainty when the spacing on the load indicating mechanism is between 1 mm [0.04 in.] and 2 mm [0.06 in.]. When the spacing is between 2 and 3 mm [0.06 and 0.12 in.], one third of a scale interval is readable with reasonable certainty. When the spacing is 3 mm

[0.12 in.] or more, one fourth of a scale interval is readable with reasonable certainty.

5.3.2 If the testing machine load is indicated in digital form, the numerical display must be large enough to be easily read.



3


C39/C39M − 12a

The numerical increment must be equal to or less than 0.10 % of the full scale load of a given loading range. In no case shall the verified loading range include loads less than the minimum numerical increment multiplied by 100. The accuracy of the indicated load must be within 1.0 % for any value displayed within the verified loading range. Provision must be made for adjusting to indicate true zero at zero load. There shall be provided a maximum load indicator that at all times until reset will indicate within 1 % system accuracy the maximum load applied to the specimen.

5.4 Documentation of the calibration and maintenance of the testing machine shall be in accordance with Practice

C1077 .

6. Specimens

6.1 Specimens shall not be tested if any individual diameter of a cylinder differs from any other diameter of the same cylinder by more than 2 %.

N

OTE

9—This may occur when single use molds are damaged or deformed during shipment, when flexible single use molds are deformed during molding, or when a core drill deflects or shifts during drilling.

6.2 Prior to testing, neither end of test specimens shall depart from perpendicularity to the axis by more than 0.5°

(approximately equivalent to 1 mm in 100 mm [0.12 in. in 12 in.]). The ends of compression test specimens that are not plane within 0.050 mm [0.002 in.] shall be sawed or ground to meet that tolerance, or capped in accordance with either Practice

C617

or, when permitted, Practice

C1231/C1231M . The diam-

eter used for calculating the cross-sectional area of the test specimen shall be determined to the nearest 0.25 mm [0.01 in.] by averaging two diameters measured at right angles to each other at about midheight of the specimen.

6.3 The number of individual cylinders measured for determination of average diameter is not prohibited from being reduced to one for each ten specimens or three specimens per day, whichever is greater, if all cylinders are known to have been made from a single lot of reusable or single-use molds which consistently produce specimens with average diameters within a range of 0.5 mm [0.02 in.]. When the average diameters do not fall within the range of 0.5 mm [0.02 in.] or when the cylinders are not made from a single lot of molds, each cylinder tested must be measured and the value used in calculation of the unit compressive strength of that specimen.

When the diameters are measured at the reduced frequency, the cross-sectional areas of all cylinders tested on that day shall be computed from the average of the diameters of the three or more cylinders representing the group tested that day.

6.4 If the purchaser of the testing services requests measurement of density of test specimens, determine the mass of specimens before capping. Remove any surface moisture with a towel and measure the mass of the specimen using a balance or scale that is accurate to within 0.3 % of the mass being measured. Measure the length of the specimen to the nearest 1 mm [0.05 in.] at three locations spaced evenly around the circumference. Compute the average length and record to the nearest 1 mm [0.05 in.]. Alternatively, determine the cylinder density by weighing the cylinder in air and then submerged under water at 23.0

6 2.0 °C [73.5

6 3.5 °F], and computing the volume according to

8.3.1

.

6.5 When density determination is not required and the length to diameter ratio is less than 1.8 or more than 2.2, measure the length of the specimen to the nearest 0.05 D.

7. Procedure

7.1 Compression tests of moist-cured specimens shall be made as soon as practicable after removal from moist storage.

7.2 Test specimens shall be kept moist by any convenient method during the period between removal from moist storage and testing. They shall be tested in the moist condition.

7.3 All test specimens for a given test age shall be broken within the permissible time tolerances prescribed as follows:

Test Age Permissible Tolerance

24 h

3 days

7 days

28 days

90 days

± 0.5 h or 2.1 %

2 h or 2.8 %

6 h or 3.6 %

20 h or 3.0 %

2 days 2.2 %

7.4

Placing the Specimen— Place the plain (lower) bearing block, with its hardened face up, on the table or platen of the testing machine directly under the spherically seated (upper) bearing block. Wipe clean the bearing faces of the upper and lower bearing blocks and of the test specimen and place the test specimen on the lower bearing block. Carefully align the axis of the specimen with the center of thrust of the spherically seated block.

7.4.1

Zero Verification and Block Seating —Prior to testing the specimen, verify that the load indicator is set to zero. In cases where the indicator is not properly set to zero, adjust the

indicator ( Note 10 ). After placing the specimen in the machine

but prior to applying the load on the specimen, tilt the movable portion of the spherically seated block gently by hand so that the bearing face appears to be parallel to the top of the test specimen.

N

OTE

10—The technique used to verify and adjust load indicator to zero will vary depending on the machine manufacturer. Consult your owner’s manual or compression machine calibrator for the proper technique.

7.5

Rate of Loading— Apply the load continuously and without shock.

7.5.1 The load shall be applied at a rate of movement (platen to crosshead measurement) corresponding to a stress rate on the specimen of 0.25

6 0.05 MPa/s [35 6 7 psi/s] (See

Note

11 ). The designated rate of movement shall be maintained at

least during the latter half of the anticipated loading phase.

N

OTE

11—For a screw-driven or displacement-controlled testing machine, preliminary testing will be necessary to establish the required rate of movement to achieve the specified stress rate. The required rate of movement will depend on the size of the test specimen, the elastic modulus of the concrete, and the stiffness of the testing machine.

7.5.2 During application of the first half of the anticipated loading phase, a higher rate of loading shall be permitted. The higher loading rate shall be applied in a controlled manner so that the specimen is not subjected to shock loading.

7.5.3 Make no adjustment in the rate of movement (platen to crosshead) as the ultimate load is being approached and the stress rate decreases due to cracking in the specimen.



4


C39/C39M − 12a

7.6 Apply the compressive load until the load indicator shows that the load is decreasing steadily and the specimen displays a well-defined fracture pattern (Types 1 to 4 in

Fig. 2 ).

For a testing machine equipped with a specimen break detector, automatic shut-off of the testing machine is prohibited until the load has dropped to a value that is less than 95 % of the peak load. When testing with unbonded caps, a corner fracture similar to a Type 5 or 6 pattern shown in

Fig. 2

may occur before the ultimate capacity of the specimen has been attained.

Continue compressing the specimen until the user is certain that the ultimate capacity has been attained. Record the maximum load carried by the specimen during the test, and note the type of fracture pattern according to

Fig. 2 . If the

fracture pattern is not one of the typical patterns shown in

Fig.

2 , sketch and describe briefly the fracture pattern. If the

measured strength is lower than expected, examine the fractured concrete and note the presence of large air voids, evidence of segregation, whether fractures pass predominantly around or through the coarse aggregate particles, and verify end preparations were in accordance with Practice

C617

or

Practice

C1231/C1231M .

8. Calculation

8.1 Calculate the compressive strength of the specimen by dividing the maximum load carried by the specimen during the test by the average cross-sectional area determined as described in Section

6

and express the result to the nearest 0.1

MPa [10 psi].

8.2 If the specimen length to diameter ratio is 1.75 or less, correct the result obtained in

8.1

by multiplying by the appropriate correction factor shown in the following table

Note

12 :

L/D:

Factor:

1.75

0.98

1.50

0.96

1.25

0.93

1.00

0.87

Use interpolation to determine correction factors for L/D values between those given in the table.

N

OTE

12—Correction factors depend on various conditions such as moisture condition, strength level, and elastic modulus. Average values are given in the table. These correction factors apply to low-density concrete weighing between 1600 and 1920 kg/m 3 [100 and 120 lb/ft 3 ] and to normal-density concrete. They are applicable to concrete dry or soaked at

FIG. 2 Schematic of Typical Fracture Patterns



5


C39/C39M − 12a the time of loading and for nominal concrete strengths from 14 to 42 MPa

[2000 to 6000 psi]. For strengths higher than 42 MPa [6000 psi] correction factors may be larger than the values listed above 3 .

8.3 When required, calculate the density of the specimen to the nearest 10 kg/m

3

[1 lb/ft

3

] as follows:

Density 5

W

V

(2) where:

W = mass of specimen, kg [lb], and

V = volume of specimen computed from the average diameter and average length or from weighing the cylinder in air and submerged, m

3

[ft

3

]

8.3.1 When the volume is determined from submerged weighing, calculate the volume as follows:

V 5

W 2 W s

γ w

(3) where:

W

γ w s

= apparent mass of submerged specimen, kg [lb], and

= density of water at 23 °C [73.5 °F] = 997.5 kg/m

3

[62.27 lbs/ft

3

].

9. Report

9.1 Report the following information:

9.1.1 Identification number,

9.1.2 Average measured diameter (and measured length, if outside the range of 1.8

D to 2.2

D ), in millimetres [inches],

9.1.3 Cross-sectional area, in square millimetres [square inches],

9.1.4 Maximum load, in kilonewtons [pounds-force],

9.1.5 Compressive strength calculated to the nearest 0.1

MPa [10 psi],

9.1.6 Type of fracture (see

Fig. 2 ),

9.1.7 Defects in either specimen or caps, and,

9.1.8 Age of specimen.

m 3

9.1.9 When determined, the density to the nearest 10 kg/

[1 lb/ft 3 ].

10. Precision and Bias

10.1

Precision

10.1.1

Within-Test Precision— The following table provides the within-test precision of tests of 150 by 300 mm [6 by 12 in.] and 100 by 200 mm [4 by 8 in.] cylinders made from a well-mixed sample of concrete under laboratory conditions and under field conditions (see

10.1.2

).

Coefficient of

Variation 4

Acceptable Range 4 of

Individual Cylinder Strengths

2 cylinders 3 cylinders

150 by 300 mm

[6 by 12 in.]

Laboratory conditions

Field conditions

100 by 200 mm

[4 by 8 in.]

Laboratory conditions

2.4 %

2.9 %

3.2 %

6.6 %

8.0 %

9.0 %

7.8 %

9.5 %

10.6 %

10.1.2 The within-test coefficient of variation represents the expected variation of measured strength of companion cylinders prepared from the same sample of concrete and tested by one laboratory at the same age. The values given for the within-test coefficient of variation of 150 by 300 mm [6 by 12 in.] cylinders are applicable for compressive strengths between

2000 and 15 to 55 MPa [8000 psi] and those for 100 by 200 mm [4 by 8 in.] cylinders are applicable for compressive strengths between 17 to 32 MPa [2500 and 4700 psi]. The within-test coefficients of variation for 150 by 300 mm [6 by 12 in.] cylinders are derived from CCRL concrete proficiency sample data for laboratory conditions and a collection of 1265 test reports from 225 commercial testing laboratories in 1978.

5

The within-test coefficient of variation of 100 by 200 mm [4 by

8 in.] cylinders are derived from CCRL concrete proficiency sample data for laboratory conditions.

10.1.3

Multilaboratory Precision— The multi-laboratory coefficient of variation for compressive strength test results of

150 by 300 mm [6 by 12 in.] cylinders has been found to be

5.0 %

4

; therefore, the results of properly conducted tests by two laboratories on specimens prepared from the same sample of concrete are not expected to differ by more than 14 %

4 of the average (See

Note 13 ). A strength test result is the average of

two cylinders tested at the same age.

N OTE 13—The multilaboratory precision does not include variations associated with different operators preparing test specimens from split or independent samples of concrete. These variations are expected to increase the multilaboratory coefficient of variation.

10.1.4 The multilaboratory data were obtained from six separate organized strength testing round robin programs where 150 x 300 mm [6 x 12 in.] cylindrical specimens were prepared at a single location and tested by different laboratories. The range of average strength from these programs was

17.0 to 90 MPa [2500 to 13 000 psi].

N

OTE

14—Subcommittee C09.61 will continue to examine recent concrete proficiency sample data and field test data and make revisions to precisions statements when data indicate that they can be extended to cover a wider range of strengths and specimen sizes.

10.2

Bias— Since there is no accepted reference material, no statement on bias is being made.

3 Bartlett, F.M. and MacGregor, J.G., “Effect of Core Length-to-Diameter Ratio on Concrete Core Strength,” ACI Materials Journal , Vol 91, No. 4, July-August,

1994 , pp. 339-348.

4 These numbers represent respectively the (1s %) and (d2s %) limits as described in Practice

C670 .

5 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:C09-1006.



6


C39/C39M − 12a

SUMMARY OF CHANGES

Committee C09 has identified the location of selected changes to this test method since the last issue,

C39/C39M–12, that may impact the use of this test method. (Approved September 1, 2012)

( 1 ) Revised

5.1.1.1

.


C39/C39M–11a, that may impact the use of this test method. (Approved February 1, 2012)

( 1 ) Revised

9.1.6

.


C39/C39M–11, that may impact the use of this test method. (Approved October 15, 2011)

( 1 ) Revised

5.2.2.4

. Added new Note 7

and renumbered subsequent notes.


C39/C39M–10, that may impact the use of this test method. (Approved August 1, 2011)

( 1 ) Added new

5.4

.

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below.

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(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/

COPYRIGHT/).



7


Designation: C469/C469M − 10


Static Modulus of Elasticity and Poisson’s Ratio of Concrete in Compression

1

This standard is issued under the fixed designation C469/C469M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.

A superscript epsilon ( ´ ) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This test method covers determination of ( 1 ) chord modulus of elasticity (Young’s) and ( 2 ) Poisson’s ratio of molded concrete cylinders and diamond-drilled concrete cores when under longitudinal compressive stress. Chord modulus of elasticity and Poisson’s ratio are defined in Terminology

E6 .

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.3



2.1

ASTM Standards: 2

C31/C31M



C39/C39M

Test Method for Compressive Strength of Cylindrical Concrete Specimens

C42/C42M



C174/C174M

Test Method for Measuring Thickness of Concrete Elements Using Drilled Concrete Cores

C192/C192M



C617

Practice for Capping Cylindrical Concrete Specimens

E4

Practices for Force Verification of Testing Machines


Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee

C09.61


Current edition approved Oct. 1, 2010. Published November 2010. Originally approved in 1961. Last previous edition approved in 2002 as C469 – 02 ´ 1 . DOI:

10.1520/C0469_C0469M-10.



E6

Terminology Relating to Methods of Mechanical Testing

E83

Practice for Verification and Classification of Extensometer Systems

E177

Practice for Use of the Terms Precision and Bias in

ASTM Test Methods

2.2

ASTM Adjuncts:

Compressometers (two drawings) and Extensometers (two drawings)

3


3.1 This test method provides a stress to strain ratio value and a ratio of lateral to longitudinal strain for hardened concrete at whatever age and curing conditions may be designated.

3.2 The modulus of elasticity and Poisson’s ratio values, applicable within the customary working stress range (0 to

40 % of ultimate concrete strength), are used in sizing of reinforced and nonreinforced structural members, establishing the quantity of reinforcement, and computing stress for observed strains.

3.3 The modulus of elasticity values obtained will usually be less than moduli derived under rapid load application

(dynamic or seismic rates, for example), and will usually be greater than values under slow load application or extended load duration, given other test conditions being the same.

4. Apparatus

4.1

Testing Machine— Use a testing machine capable of imposing a load at the rate and of the magnitude prescribed in

6.4

. The machine shall conform to the requirements of Prac-

tices

E4

(Constant-Rate of-Traverse CRT-Type Testing Machines section). The spherical head and bearing blocks shall conform to the Apparatus Section of Test Method

C39/C39M .

4.2

Compressometer

3

elasticity use a bonded (

— For determining the modulus of

Note 1 ) or unbonded sensing device

that measures to the nearest 5 millionths the average deformation of two diametrically opposite gauge lines, each parallel to the axis, and each centered about midheight of the specimen.

3 Available from ASTM International Headquarters. Order Adjunct No.

ADJC0469 .




1


FIG. 1 Suitable Compressometer

C469/C469M − 10

The effective length of each gauge line shall be not less than three times the maximum size of the aggregate in the concrete nor more than two thirds the height of the specimen; the preferred length of the gauge line is one half the height of the specimen. Either use gauge points embedded in or cemented to the specimen, and read deformation of the two lines independently; or use a compressometer (such as is shown in

Fig. 1 )

consisting of two yokes, one of which (see B ,

Fig. 1 ) is rigidly

attached to the specimen and the other (see C ,

Fig. 1 ) attached

at two diametrically opposite points so that it is free to rotate.

At one point on the circumference of the rotating yoke, midway between the two support points, use a pivot rod (see A ,

Fig. 1 ) to maintain a constant distance between the two yokes.

At the opposite point on the circumference of the rotating yoke, the change in distance between the yokes (that is, the gauge reading) is equal to the sum of the displacement due to specimen deformation and the displacement due to rotation of the yoke about the pivot rod (see

Fig. 2 ).

4.2.1 Measure deformation by a dial gauge used directly or with a lever multiplying system, by a wire strain gauge, or by a linear variable differential transformer. If the distances of the pivot rod and the gauge from the vertical plane passing through the support points of the rotating yoke are equal, the deformad = displacement due to specimen deformation r = displacement due to rotation of the yoke about the pivot rod a = location of gauge b = support point of the rotating yoke c = location of pivot rod g = gauge reading

FIG. 2 Diagram of Displacements tion of the specimen is equal to one-half the gauge reading. If these distances are not equal, calculate the deformation as follows: d 5 ge r

/ ~ e r

1 e g

!

(1) where: d = total deformation of the specimen throughout the effective gauge length, µm [µin.], g = gauge reading, µm [µin.], e r

= the perpendicular distance, measured to the nearest 0.2

mm [0.01 in.] from the pivot rod to the vertical plane passing through the two support points of the rotating e g yoke, and


mm [0.01 in.] from the gauge to the vertical plane passing through the two support points of the rotating yoke.

Procedures for calibrating strain-measuring devices are given in Practice

E83 .

N OTE 1—Although bonded strain gauges are satisfactory on dry specimens, they may be difficult, if not impossible, to mount on specimens continually moist-cured until tested.

4.3

Extensometer

3

— If Poisson’s ratio is desired, the transverse strain shall be determined ( 1 ) by an unbonded extensometer capable of measuring to the nearest 0.5 µm [25 µin.] the change in diameter at the midheight of the specimen, or ( 2 ) by

two bonded strain gauges ( Note 1 ) mounted circumferentially

at diametrically opposite points at the midheight of the specimen and capable of measuring circumferential strain to the nearest 5 millionths. A combined compressometer and

extensometer ( Fig. 3 ) is a convenient unbonded device. This

apparatus shall contain a third yoke (consisting of two equal segments) located halfway between the two compressometer yokes and attached to the specimen at two diametrically opposite points. Midway between these points use a short pivot rod ( A

8

, see

Fig. 3 ), adjacent to the long pivot rod, to maintain

a constant distance between the bottom and middle yokes.

Hinge the middle yoke at the pivot point to permit rotation of the two segments of the yoke in the horizontal plane. At the



2


C469/C469M − 10

FIG. 3 Suitable Combined Compressometer-Extensometer opposite point on the circumference, connect the two segments through a dial gauge or other sensing device capable of measuring transverse deformation to the nearest 1.27 µm [50

µin.]. If the distances of the hinge and the gauge from the vertical plane passing through the support points of the middle yoke are equal, the transverse deformation of the specimen diameter is equal to one-half the gauge reading. If these distances are not equal, calculate the transverse deformation of the specimen diameter in accordance with

Eq 2 .

d

8

5 g

8 e

8 h

/ ~ e

8 h

1 e

8 g

!

(2) where: d

8

= transverse deformation of the specimen diameter, µm

[µin.], g

8

= transverse gauge reading, µm [µin.], e

8 h


mm [0.01 in.] from the hinge to the vertical plane e

8 g passing through the support points of the middle yoke, and


mm [0.01 in.] from the gauge to the vertical plane passing through the support points of the middle yoke.

4.4

Balance or Scale, accurate to 50 g [0.1 lb] shall be used if necessary.


5.1

Molded Cylindrical Specimens— Mold test cylinders in accordance with the requirements for compression test specimens in Practice

C192/C192M , or in Practice C31/C31M .

Subject specimens to the specified curing conditions and test at the age for which the elasticity information is desired. Test specimens within 1 h after removal from the curing or storage room. Specimens removed from a moist room for test shall be kept moist by a wet cloth covering during the interval between removal and test.

5.2

Drilled Core Specimens— Cores shall comply with the requirements for drilling, and moisture conditioning applicable to compressive strength specimens in Test Method

C42/C42M ,

except that only diamond-drilled cores having a length-todiameter ratio greater than 1.50 shall be used. Requirements relative to storage and to ambient conditions immediately prior to test shall be the same as for molded cylindrical specimens.

5.3 The ends of the test specimens shall be made perpendicular to the axis 6 0.001 rad [ 6 0.5°] and plane within 0.05

mm [0.002 in.]. If the specimen as cast does not meet the planeness requirements, planeness shall be accomplished by capping in accordance with Practice

C617 , or by lapping, or by

grinding. It is not prohibited to repair aggregate popouts that occur at the ends of specimens, provided the total area of popouts does not exceed 10 % of the specimen area and the

repairs are made before capping or grinding is completed ( Note

2 ). Planeness will be considered within tolerance when a 0.05

mm [0.002 in.] feeler gauge will not pass between the specimen surface and a straight edge held against the surface.

N

OTE

2—Repairs may be made by epoxying the dislodged aggregate back in place or by filling the void with capping material and allowing adequate time for it to harden.

5.4 Measure the diameter of the test specimen by caliper to the nearest 0.2 mm [0.01 in.] by averaging two diameters measured at right angles to each other near the center of the length of the specimen. Use this average diameter to calculate the cross-sectional area. Measure and report the length of a molded specimen, including caps, to the nearest 2 mm [0.1 in.].

Measure the length of a drilled specimen in accordance with

Test Method

C174/C174M ; report the length, including caps,

to the nearest 2 mm [0.1 in.].

6. Procedure

6.1 Maintain the ambient temperature and humidity as constant as possible throughout the test. Record any unusual fluctuation in temperature or humidity in the report.

6.2 Use companion specimens to determine the compressive strength in accordance with Test Method

C39/C39M

prior to the test for modulus of elasticity.

6.3 Place the specimen, with the strain-measuring equipment attached, on the lower platen or bearing block of the testing machine. Carefully align the axis of the specimen with the center of thrust of the spherically-seated upper bearing block. Note the reading on the strain indicators. As the



3


C469/C469M − 10 spherically-seated block is brought slowly to bear upon the specimen, rotate the movable portion of the block gently by hand so that uniform seating is obtained.

6.4 Load the specimen at least twice. Do not record any data during the first loading. Base calculations on the average of the

results of the subsequent loadings ( Note 3 ).

N

OTE

3—At least two subsequent loadings are recommended so that the repeatability of the test may be noted.

During the first loading, which is primarily for the seating of

the gauges, observe the performance of the gauges ( Note 4 )

and correct any unusual behavior prior to the second loading.

Obtain each set of readings as follows: Apply the load continuously and without shock. Set testing machines of the screw type so that the moving head travels at a rate of about

1 mm/min [0.05 in./min] when the machine is running idle. In hydraulically operated machines, apply the load at a constant rate within the range 250 6 50 kPa/s [35 6 7 psi/s]. Record, without interruption of loading, the applied load and longitudinal strain at the point ( 1 ) when the longitudinal strain is 50 millionths and ( 2 ) when the applied load is equal to 40 % of the ultimate load (see

6.5

). Longitudinal strain is defined as the

total longitudinal deformation divided by the effective gauge length. If Poisson’s ratio is to be determined, record the transverse strain at the same points. If a stress-strain curve is to be determined, take readings at two or more intermediate points without interruption of loading; or use an instrument that makes a continuous record. Immediately upon reaching the maximum load, except on the final loading, reduce the load to zero at the same rate at which it was applied. If the observer fails to obtain a reading, complete the loading cycle and then repeat it. Record the extra cycle in the report.

N

OTE

4—Where a dial gauge is used to measure longitudinal deformation, it is convenient to set the gauge before each loading so that the indicator will pass the zero point at a longitudinal strain of 50 millionths.

6.5 It is not prohibited to obtain the modulus of elasticity and strength on the same loading provided that the gauges are expendable, removable, or adequately protected so that it is possible to comply with the requirement for continuous loading given in Test Method

C39/C39M . In this case record several

readings and determine the strain value at 40 % of the ultimate by interpolation.

6.6 If intermediate readings are taken, plot the results of each of the three tests with the longitudinal strain as the abscissa and the compressive stress as the ordinate. Calculate the compressive stress by dividing the quotient of the testing machine load by the cross-sectional area of the specimen determined in accordance with

5.4

.

7. Calculation

7.1 Calculate the modulus of elasticity, to the nearest

200 MPa [50,000 psi] as follows:

E 5 ~ S

2

2 S

1

!

/ ~ ´

2

2 0.000050

!

(3) where:

E = chord modulus of elasticity, MPa [psi],

S

S

2

1

= stress corresponding to 40 % of ultimate load,

= stress corresponding to a longitudinal strain, millionths, MPa [psi], and

´

1

, of 50

´

2

= longitudinal strain produced by stress S

2

.

7.2 Calculate Poisson’s ratio, to the nearest 0.01, as follows: m 5 ~ ´ t2

2 ´ t1

!

/ ~ ´

2

2 0.000050

!

(4) where:

µ = Poisson’s ratio,

´ t2

= transverse strain at midheight of the specimen pro-

´ t1 duced by stress S

2

, and

= transverse strain at midheight of the specimen produced by stress S

1

.

8. Report


8.1.1 Specimen identification number,

8.1.2 Dimensions of specimen, in millimetres [inches],

8.1.3 Curing and environmental histories of the specimen,

8.1.4 Age of the specimen,

8.1.5 Strength of the concrete, if determined,

8.1.6 Unit weight of the concrete, if determined,

8.1.7 Stress-strain curves, if plotted,

8.1.8 Chord modulus of elasticity, and

8.1.9 Poisson’s ratio, if determined.


9.1

Precision— The single-operator-machine multibatch precision is 6 4.25 % (R1S %) max, as defined in Practice

E177 , over the range from 17 to 28 GPa [2.5 to 4 × 10

6 psi]; therefore, the results of tests of duplicate cylinders from different batches should not depart more than 5 % from the average of the two.

9.2

Bias— This test method has no bias because the values determined can only be defined in terms of the test method.

10. Keywords

10.1 compression testing; concrete; modulus of elasticity;

Poisson’s ratio



4


C469/C469M − 10






COPYRIGHT/).



5


Designation: C496/C496M − 11


Splitting Tensile Strength of Cylindrical Concrete

Specimens

1

This standard is issued under the fixed designation C496/C496M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.

A superscript epsilon ( ´ ) indicates an editorial change since the last revision or reapproval.


1. Scope*

1.1 This test method covers the determination of the splitting tensile strength of cylindrical concrete specimens, such as molded cylinders and drilled cores.

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.3


1.4 The text of this standard references notes that provide explanatory material. These notes shall not be considered as requirements of the standard.


2.1

ASTM Standards:

2

C31/C31M



C39/C39M

Test Method for Compressive Strength of Cylindrical Concrete Specimens

C42/C42M



C192/C192M



C670

Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials


Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee

C09.61


Current edition approved July 1, 2011. Published August 2011. Originally approved in 1962. Last previous edition approved in 2004 as C496–04 ´ 1 . DOI:

10.1520/C0496_C0496M-11.



3. Summary of Test Method

3.1 This test method consists of applying a diametral compressive force along the length of a cylindrical concrete specimen at a rate that is within a prescribed range until failure occurs. This loading induces tensile stresses on the plane containing the applied load and relatively high compressive stresses in the area immediately around the applied load.

Tensile failure occurs rather than compressive failure because the areas of load application are in a state of triaxial compression, thereby allowing them to withstand much higher compressive stresses than would be indicated by a uniaxial compressive strength test result.

3.2 Thin, plywood bearing strips are used to distribute the load applied along the length of the cylinder.

3.3 The maximum load sustained by the specimen is divided by appropriate geometrical factors to obtain the splitting tensile strength.


4.1 Splitting tensile strength is generally greater than direct tensile strength and lower than flexural strength (modulus of rupture).

4.2 Splitting tensile strength is used in the design of structural lightweight concrete members to evaluate the shear resistance provided by concrete and to determine the development length of reinforcement.

5. Apparatus

5.1

Testing Machine— The testing machine shall conform to the requirements of Test Method

C39/C39M

and be of a type with sufficient capacity that will provide the rate of loading prescribed in

7.5

.

5.2

Supplementary Bearing Bar or Plate— If the diameter or the largest dimension of the upper bearing face or the lower bearing block is less than the length of the cylinder to be tested, a supplementary bearing bar or plate of machined steel shall be used. The surfaces of the bar or plate shall be machined to within 6 0.025 mm [ 6 0.001 in.] of planeness, as measured on any line of contact of the bearing area. It shall have a width of at least 50 mm [2 in.], and a thickness not less than the distance





1


from the edge of the spherical or rectangular bearing block to the end of the cylinder. The bar or plate shall be used in such manner that the load will be applied over the entire length of the specimen.

5.3

Bearing Strips— Two bearing strips of nominal 3.0 mm

[ 1 ⁄

8 in.] thick plywood, free of imperfections, approximately 25 mm [1 in.] wide, and of a length equal to, or slightly longer than, that of the specimen shall be provided for each specimen.

The bearing strips shall be placed between the specimen and both the upper and lower bearing blocks of the testing machine or between the specimen and supplemental bars or plates, when used (see

5.2

). Bearing strips shall not be reused.


6.1 The test specimens shall conform to the size, molding, and curing requirements set forth in either Practice

C31/C31M

(field specimens) or Practice

C192/C192M

(laboratory specimens). Drilled cores shall conform to the size and moistureconditioning requirements set forth in Test Method

C42/C42M .

Moist-cured specimens, during the period between their removal from the curing environment and testing, shall be kept moist by a wet burlap or blanket covering, and shall be tested in a moist condition as soon as practicable.

6.2 The following curing procedure shall be used for evaluations of light-weight concrete: specimens tested at 28 days shall be in an air-dry condition after 7 days moist curing followed by 21 days drying at 23.0

6 2.0°C [73.5

6 3.5°F] and

50 6 5 % relative humidity.

7. Procedure

7.1

Marking— Draw diametral lines on each end of the specimen using a suitable device that will ensure that they are in the same axial plane (see

Fig. 1 ,

Fig. 2

and

Note 1 ), or as an

C496/C496M − 11 alternative, use the aligning jig shown in

Fig. 3

( Note 2 ).

N

OTE

1— Figs. 1 and 2

show a suitable device for drawing diametral lines on each end of a 150 mm × 300 mm [6 in. × 12 in.] cylinder in the same axial plane. The device consists of three parts as follows:

(1) A length of 100-mm [4-in.] steel channel, the flanges of which have been machined flat,

(2) A section, part a, that is grooved to fit smoothly over the flanges of the channel and that includes cap screws for positioning the vertical member of the assembly, and

(3) A vertical bar, part b, for guiding a pencil or marker,

The assembly (part a and part b) is not fastened to the channel and is positioned at either end of the cylinder without disturbing the position of the specimen when marking the diametral lines.

N

OTE

2— Fig. 4

is a detailed drawing of the aligning jig shown in

Fig.

3

for achieving the same purpose as marking the diametral lines. The device consists of:

(1) A base for holding the lower bearing strip and cylinder,

(2) A supplementary bearing bar conforming to the requirements in

Section

5

as to critical dimensions and planeness, and

(3) Two uprights to serve for positioning the test cylinder, bearing strips, and supplementary bearing bar.

7.2

Measurements— Determine the diameter of the test specimen to the nearest 0.25 mm [0.01 in.] by averaging three diameters measured near the ends and the middle of the specimen and lying in the plane containing the lines marked on the two ends. Determine the length of the specimen to the nearest 2 mm [0.1 in.] by averaging at least two length measurements taken in the plane containing the lines marked on the two ends.

7.3

Positioning Using Marked Diametral Lines— Center one of the plywood strips along the center of the lower bearing block. Place the specimen on the plywood strip and align so that the lines marked on the ends of the specimen are vertical and centered over the plywood strip. Place a second plywood

FIG. 1 General Views of a Suitable Apparatus for Marking End Diameters Used for Alignment of Specimen in Testing Machine



2


C496/C496M − 11

FIG. 2 Detailed Plans for a Suitable Apparatus for Marking End Diameters Used for Aligning the Specimen

FIG. 3 Jig for Aligning Concrete Cylinder and Bearing Strips strip lengthwise on the cylinder, centered on the lines marked on the ends of the cylinder. Position the assembly to ensure the following conditions:

7.3.1 The projection of the plane of the two lines marked on the ends of the specimen intersects the center of the upper bearing plate, and

7.3.2 The supplementary bearing bar or plate, when used, and the center of the specimen are directly beneath the center of thrust of the spherical bearing block (see

Fig. 5 ).

7.4

Positioning by Use of Aligning Jig— Position the bearing strips, test cylinder, and supplementary bearing bar by means of the aligning jig as illustrated in

Fig. 3

and center the jig so that the supplementary bearing bar and the center of the specimen are directly beneath the center of thrust of the spherical bearing block.

7.5

Rate of Loading— Apply the load continuously and without shock, at a constant rate within the range 0.7 to 1.4

MPa/min [100 to 200 psi/min] splitting tensile stress until

failure of the specimen ( Note 3 ). Record the maximum applied

load indicated by the testing machine at failure. Note the type of failure and the appearance of the concrete.

N OTE 3—The relationship between splitting tensile stress and applied load is shown in Section

8 . The required loading range in splitting tensile

stress corresponds to applied total load in the range of 50 to 100 kN/min

[11 300 to 22 600 lbf/min] for 150 by 300-mm [6 by 12-in.] cylinders.



3


C496/C496M − 11

FIG. 4 Detailed Plans for a Suitable Aligning Jig for 150 × 300 mm [6 × 12 in.] Specimen

8. Calculation

8.1 Calculate the splitting tensile strength of the specimen as follows:

FIG. 5 Specimen Positioned in a Testing Machine for Determination of Splitting Tensile Strength where:

T = splitting tensile strength, MPa [psi],

P = maximum applied load indicated by the testing machine,

N [lbf],

T 5 2 P / p ld (1)



4


l = length, mm [in.], and d = diameter, mm [in.].

9. Report


9.1.1 Identification number,

9.1.2 Diameter and length, in. [mm],

9.1.3 Maximum load, lbf [N],

9.1.4 Splitting tensile strength calculated to the nearest 0.05

MPa [5 psi],

9.1.5 Estimated proportion of coarse aggregate fractured during test,

9.1.6 Age of specimen,

9.1.7 Curing history,

9.1.8 Defects in specimen,

9.1.9 Type of fracture, and

9.1.10 Type of specimen.

C496/C496M − 11


10.1

Precision— An interlaboratory study of this test method has not been performed. Available research data, 3 however, suggests that the within batch coefficient of variation is 5 %

(see

Note 4 ) for 150 × 300-mm [6 × 12-in.] cylindrical speci-

mens with an average splitting tensile strength of 2.8 MPa [405 psi]. Results of two properly conducted tests on the same material, therefore, should not differ by more than 14 % (see

Note 4 ) of their average for splitting tensile strengths of about

2.8 MPa [400 psi].

N

OTE

4—These numbers represent, respectively, the (1s %) and (d2s %) limits as defined in Practice

C670 .

10.2

Bias— The test method has no bias because the splitting tensile strength can be defined only in terms of this test method.

11. Keywords

11.1 cylindrical concrete specimens; splitting tension; tensile strength

3 Wright, P. J. F., “Comments on an Indirect Tensile Test on Concrete Cylinders,”

Magazine of Concrete Research, Vol 7, No. 20, July 1955, pp. 87–95.

SUMMARY OF CHANGES


C496–04

´ 1

, that may impact the use of this test method. (Approved July 1, 2011)

( 1 ) Reversed the order of units in the test method so that SI units appear first.






COPYRIGHT/).



5





Laboratory Experiment VII

MECHANICAL PROPERTIES OF WOOD

Part A: Flexure Test of Clear Wood

1 OBJECTIVES

1.

To determine the mechanical properties of clear wood subjected to bending

2.

To observe the behavior of the material under load, and to study the failure.

1.1

Background

1.1.1 Beam Theory

The flexure test allows a material to be subjected to a tensile stress without preparing a tensile specimen such as used for metals. For instance, it is very difficult to make a "pure" tensile specimen, but it is easy to prepare a flexure specimen. The evaluation of the flexure test requires the use of the analysis of stress and strain in a "beam" There is an extensive study of beams that is part of the subject "Mechanics" which is taught in CE 130. There is a short description of the internal forces in beams in E36, but the major study of the subject is covered in CE 130. In this laboratory you will have a chance to see the way the flexure test works, and you should get a good physical impression of the way the internal forces in the flexure specimen cause the wood to fail.

A schematic diagram of a deflected beam is shown in Fig. 1 in which the undisturbed beam is shown immediately below the deformed beam. The deformation is distorted to make the deformed shape clearly different than the undisturbed shape below. Note the x & y are in the plane of the paper. We will assume that planar cross sections perpendicular to the axis of the beam remain plane and perpendicular to the bent axis of the beam. We will also assume that straight lines parallel to the beam axis assume a bent or curved configuration.

As a consequence of the bending shown in Fig. 1, lines nearer the center of curvature of the beam shorten while lines on the convex side (bottom) of the beam are elongated. Somewhere in the middle of the beam there must be a line whose length remains unchanged. Lin AB in

Fig. 1 appears to fit this description, and it is called the neutral axis. The x-axis is chosen to coincide with the neutral axis when the beam is unbent. The y-axis is vertical in Fig. 1 and the z-axis is positive when it comes out of the paper. The x-y plane is called the neutral plane.



Figure 1 – A Schematic diagram of a deflected beam is shown in which the undisturbed beam is shown immediately below the deformed beam.

1.1.2 Definitions

Modulus of Rupture is a measure of the ability of a beam to support a slowly applied load for a short time. It is based on the use of Equation A-9 for the tensile stress in the outer fiber of the simply supported flexure specimen of span, L. It is used as a criterion for strength, although it does not represent true stress since the Equation A-9 used in computing the modulus of rupture used the assumption of linear elasticity in Equation A-6, and thus it is valid only up to the proportional limit, whereas the load involved in the computations for the modulus is the load at failure.

σ

max

=

Mc

I

=

M bh 3

1

2

12 h

=

6 M bh 2

(1) where M is bending moment,

P

2

∗

L

2

=

PL

4


Department of Civil and Environment Engineering c is distance from neutral axis to outer fiber, b is the width of the beam, h is the full height of the beam. (i.e., 2c) bh 3

I is moment of inertia,

12

P = applied load, and

L = span between supports.

Modulus of Elasticity , E, is a measure of stiffness of the material. For a beam, the modulus of elasticity is a measure of its resistance to deflection. The modulus of elasticity as determined from the flexural test includes deflection due to shear distortion. The modulus of elasticity in compression parallel to the grain is generally 10% higher.

PL 3

Δ

=

48 EI

Δ is the deflection at center of simply supported beam

(2)

Modulus of Resilience is a measure of the ability of a material to store or absorb energy without permanent deformation. It can be computed from the area under the load- deformation curve by using the formula 1/2P Δ during the initial portion of the experiment.

Average Work equals area under load-deflection curve. To obtain average work in units of inch-pounds per cubic inch, divide work by volume of material subjected to loading.

Proportional Limit is where the load vs deflection curve deviates from linear.

1.2

Wood to be Tested

Clear, straight grained specimens of Douglas fir, 2" x 2" x 30" will be subjected to flexural loading. A deflectometer and special loading blocks are provided for the test.


1.

Measure and weigh the specimen, count the number of annual growth rings per inch, and estimate the percentage of springwood (light rings) and summerwood (dark rings). Make a sketch of each specimen in perspective, showing any defects and the direction of rings on end sections.

2.

Mark the center and end points for a 28-in. span. Draw right-section lines through these points using a square. Drive small brads into one side of the beam at mid-depth, over each end support. Set the beam supports for a 28-in. span so that they can move away from the center of span as the lower fibers elongate. Place the specimen in


Department of Civil and Environment Engineering position so that the tangential surface nearest the pith will be face up. Place the deflectometer on the brads at the supports and attach it to the center of span. See that the deflectometer fits close to the beam, and bend up the two end brads slightly so that vibrations will not displace it.

3.

Adjust the deflectometer and the testing machine to read zero.

4.

Apply the load continuously through a standardized wooden loading block at midspan at the rate 400 lb per minute, taking simultaneous load and deflectometer readings for increments of load that will give at least 10 readings before you reach half of the ultimate. You should consult your notes to anticipate what your ultimate will be. Calculate the half-to-ultimate load and verify with the instructor before proceeding.

5.

After reaching half of the anticipated ultimate, unload the specimen and determine if there is any strain remaining. Allow the specimen to "rest" for five minutes. Then reload the specimen as in step (4), except you should continue to the ultimate load.

6.

At the ultimate, observe how the failure occurred. Make a sketch to show the appearance of failure.

7.

Cut a moisture sample about 1 inch in length from the specimen near the ruptured section. Remove all splinters and weigh to the nearest 0.1 g. Place in a drying oven controlled at 103±2°C. After the moisture specimen has dried to constant weight, which may take 2 to 4 days, weigh it again.

2.1

Reduction of Data

1.

Plot a diagram showing the relation between applied-load versus deflection.

2.

Determine the moisture content and approximate specific gravity, both as received and when dry.

3 ANALYSIS AND REPORT

1.

Give the characteristics of the specimen as determined in Section 1.2 Wood to be

Tested .

2.

Present all the data described in Section 2 Test Procedure.

3.

Determine the following:

(a) Proportional limit stress in outer fiber

(b) Modulus of rupture

(c) Modulus of elasticity

(d) Average work to proportional limit, inch-pounds per cubic inch

(e) Average total work to ultimate load, inch-pounds per cubic inch

(f) Type of failure.

(Combine this report with Part B of this experiment)



APPENDIX

The following information describes how to determine the flexure formula that is used to calculate the modulus of rupture.

In figure 1, length between AB remains unchanged compared to the arc length A’B’.

Δ

x =

ρ

Δ

θ

(A-1) where ρ is the radius of curvature. The arc length of C’D’ is ( ρ - y) Δθ , where y is the height of the line CD above the neutral axis AB. Thus the strain ε xx

at a height y is

ε

xx

= lim

Δ x → 0

C ' D '

−

CD

CD

(A-2)

ε

xx

= lim

Δ x → 0

(

ρ

−

y )

Δ

θ

CD

− Δ

x

(A-3)

From Equations 1 and 2,

ε

xx

( y ) = − y d

θ

dx

= y

−

ρ

(A-4)

Because the radius of curvature varies from point to point along the beam, we may write

ε

xx

( x , y ) = − y d

θ

dx

= −

ρ

y

( x )

(A-5)

Assuming the beam is linearly elastic

σ

xx

= E

ε

xx

=

−

ρ

Ey

( x )

(A-6)

We will define M(x) as the bending moment about the z-axis .

M ( x ) =

−

∫

y

σ

xx dA =

ρ

(

E x )

∫

y 2 dA (A-7)

But from Equation 5, E/ ρ (x) = σ xx

/y, so



σ

xx

=

−

M

∫

( x )

∗

y 2 dA y

(A-8)

The integral in the denominator of Equation 8 is the second moment of area or moment of inertia about the z-axis , I zz

. Thus for elastic beams, we obtain the flexure formula for tensile stress in the beam as the following.

σ

xx

=

−

M ( x )

∗

I zz y

(A-9)




Laboratory Experiment VII

FLEXURE TEST OF WOOD

Date: Name:

Lab Partners:

Group Number:

Load to 1/2*Pmax

Load, lbs Deflection, in.


Species

Overall length, in.

Width (b), in.

Height (h), in.

Length between supports (L), in.

Weight of specimen, grams

Number of rings per inch

Springwood, percentage

Summerwood, percentage

Testing machine used

Deflectometer used

Manner of loading


Weight of as-‐received, grams

Weight of oven-‐dry, grams

Sketch of Failure:

Load to ULTIMATE

Load, lbs Deflection, in.






MECHANICAL PROPERTIES OF WOOD

Part B: Compression Test of Clear Wood

1

OBJECTIVES

1.

To study the action of wood under compressive loading parallel to the grain.

2.

Determine the modulus of elasticity, ultimate strength and other mechanical properties under compressive loading parallel to the grain.

1.1

Wood to be Tested:

The same wood as used in Part A will be utilized, if possible. A specimen 2" x 2" x

8" will be cut from one end of the flexure specimen in Part A. A compressometer with a 6" gauge length will be utilized.

2

PROCEDURES

1.

Cut a specimen 8" long from the undamaged end of the flexure specimen from Part

A. Be sure that the ends of the specimen are plane and at right angles to the axis of the specimen. Measure the cross section and length of the specimen to the nearest

0.01" and weigh to the nearest gram. Determine the average number of annual growth rings per inch, the percentage of summerwood, and the percentage of springwood

(although they should be the same as in Part A).

2.

Determine the gauge length and multiplication ratio of the compressometer.

Determine the strain corresponding to the least reading of the dial. Attach the compressometer to the specimen and remove the spacer bars. Center the specimen on the table of the testing machine using a machined bearing block at the lower end and a spherical bearing block at the upper. Adjust the compressometer dial to read zero, and make certain that most of its range is available.

3.

Apply the load continuously at a speed of 5000 lb. per minute and make measurements at intervals which will give you 10 readings at half of the ultimate load. When you reach half of the ultimate, unload the specimen and determine if there is any residual strain. As in Part A, you should anticipate the ultimate load by consulting your notes. Calculate the half-to-ultimate load and verify with the instructor before proceeding.

4.

Allow the specimen to "rest" five minutes and then reload as in step (3). Continue loading until you reach the ultimate. Draw a sketch, in perspective, indicating the grain of the wood and the manner of failure. Remove the load from the specimen.

5.

Remove the compressometer and then reload specimen and try to continue gathering the load and strain data until the specimen is destroyed.



2.1

Reduction of Data

1.

Construct a stress-strain diagram and mark the proportional limit and the yield strength on the curve.

2.

Calculate the modulus of elasticity.

3

ANALYSIS AND REPORT

1.

Present all the data described in bullet 1 of Section 2.1 Reduction of Data.

2.

Determine the following and compare to results found in Part A: a) Elastic strength: i) proportional ii) yield strength at 0.05 percent offset. b) Ultimate strength





MECHANICAL PROPOERTIES OF WOOD

NAME:____________________________

GRADE SHEET

1.

Characteristic of the specimen

2.

Presentation of the following data for the flexure test.

(1) ______ a. Plot of Load vs. Deflection for flexure test b. Proportional limit stress in outer fiber c. Modulus of Rupture d. Modulus of Elasticity from flexure test e. Average Work to proportional Limit f. Average Total Work to ultimate load

(2) ______

(1) ______

(1) ______

(1) ______

(1) ______

(1) ______

3.

Presentation of the following data for the compression test. a. Plot of Stress vs. Strain for compression test (2) ______ c. Ultimate strength (show it on stress-strain curve) (1) ______

4.

Description of the experiments and discussion of results (2) ______

5.

b. Proportional limit and 0.05% offset yield stress (1) ______

Organization and Neatness (1) ______

TOTAL (15) ______




Laboratory Experiment VII

COMPRESSION TEST OF WOOD

Date: Name:

Lab Partners:

Group Number:

Load to 1/2*Pmax

Load, lbs Length Change, in.

Load to FAILURE

Load, lbs Length Change, in.


Species

Overall length, in.

Width (b), in.

Height (h), in.

Gage Length, in.

Weight of specimen, grams

Number of rings per inch

Springwood, percentage

Summerwood, percentage

Testing machine used

Deflectometer used


Direction of Grain to loading

Weight of as-‐received, grams

Weight of oven-‐dry, grams

See Flex. data sheet









Sketch of Failure:


ce60 properties of civil engineering materials

CE60 PROPERTIES OF CIVIL

ENGINEERING MATERIALS

Laboratory Handouts

INSTRUCTIONS ON PREPARATION OF REPORTS

1.

Suggested Form for Reports:

2.

Suggested Formats for Preparing Figures:

University of California, Berkeley

Department of Civil and Environment Engineering