Sample Collected for CBR Test

 Sample

The sample shall be handled and specimen(s) for compaction shall be prepared in accordance with the procedures given in T99 or T180 for compaction in a 152.4mm (6-in) mold accept as follows:

 

If all material passes a 19.0mm (3/4 in) sieve, the entire gradation shall be used for preparing specimens for compaction without modification. If there is material retained on the 19.0-mm sieve, the material retained on the 19.0-mm sieve shall be removed and replaced by an equal amount of material passing the 19.0-mm sieve and retained on the 4.75-mm (No.4) sieve obtained by separation from portions of the sample not otherwise used for testing.

 

Bearing Ratio Optimum Water Content- From a sample having a mass of 35 kg (75 lb.) or more, select a represented portion having a mass of approximately 11kg (25 lb.) for a moisture-density test and divide the remainder of the sample to obtain three representative portions having a mass of approximately 6.8 kg (15 lb.) each.

Bearing Ratio for a Range of Water Content-From a sample having a mass of 113 kg (250 lb.) or more, select at least five representative portions having a mass of approximately 6.8kg (15 lb.) each for use in developing each compaction curve.

Figure_1----California Bearing Ratio Apparatus

 

Apparatus of CBR Test

 

41. APPARATUS

1.1. Molds­- The molds shall be cylindrical in shape, made of metal, with an internal diameter of 152.40±0.66mm (6.0±0.026 in) and a height of 177.80±0.46mm (7.0±0.018 in), and provided with an extension collar approximately 50 mm (2.0 in) in height and a perforated base plate that can be fitted to either end of the mold. (See Figure 1.) It is desirable to have at least three molds each soil to be tested.

1.2. Spacer Disk- A circular spacer disk made of metal 150.8±0.8mm (5^15/16±^1/32 in.) in diameter and 61.37±0.25mm (2.416±0.01 in.) in height.  (See Figure1.)

Note 1 –When using molds having a height of 177.80 mm (7.0 in.) (Figure 1.), a spacer disk height of 61.37 mm (2.416 in.) is needed a thickness of compacted specimen that conforms to the thickness: 116.43 mm (4.584 in.) of specimens in T 99 and T 180.

1.3. Rammer-A rammer as specified in either T 99 or T 180.

1.4. Apparatus for Measuring Expansion-This consists of a swell plate with adjustable stem (Figure 1), and a tripod support for a dial indicator (Figure 1. ). The swell plate is made of metal, 149.2 ±1.6mm (5^7/8±^1/16 in.) in diameter and is perforated with 1.6-mm (1/16-in) diameter holes. The tripod used to support the dial indicator is arranged to fit the mold extension collar.

1.5. Indicators- Two dial indicators: each indicator shall have a 25-mm (1-in.) throw and read to 0.02 mm (0.001 in.)

1.6. Surcharge Weights-One annular metal weight with a center hole approximately 54.0 mm(21/8in.) in diameter and several slotted or spilt metal weights, all 149.2 ± 1.6mm(5^7/8±^1/16 in.) in diameter and each having a mass of 2.27± 0.04 kg (5 ± 0.10lb) (Figure 1.) (Note 2.)

Note 2- When using spilt weights, the mass of the pair shall be 2.27± 0.04 kg (5 ± 0.10lb).

1.7. Penetration Piston- A metal piston of circular cross-section having a diameter of 49.63± 0.13mm (1.954 ± 0.005 in).area= 1935mm² (3 in²) and not less than 102mm (4 in) long (See Figure 1.)

1.8. Loading Device-A compression-type apparatus capable of applying a uniformly increasing load up to a capacity sufficient for the material being tested at a rate of 1.3mm/min. (0.05 in. /min), used to force the penetration piston into the specimen.

1.9. Soaking Thank-A soaking tank suitable for maintaining the water level 25 mm (1 in.) above the top of specimens.

1.10. Drying Oven- A thermostatically controlled drying oven capable of maintaining a temperature of 110± 5°C (230± 9°F) for drying moisture samples

1.11. Moisture Content Container-As specified in T 265.

1.12. Miscellaneous- Miscellaneous tools such as mixing pans, spoons, straightedge, filter paper, balance, etc.

For Further Detail ...........See (Figure 1.)

AASHTO Designation: T 193-13 (2017)

1. Scope

1.1. This test method covers the determination of the California Bearing Ratio (CBR) of pavement subgrade, sub base, and base/course materials from laboratory compacted specimens. The test method is primarily intended for, but not limited to, evaluating the strength of cohesive materials having maximum particle size less than 19 mm (3/4 in)

1.2.When material having maximum particle size greater than 19 mm (3/4 in) are to be tested, this test method provides for modifying the gradation of the material so that the material used for test all passes the 19 mm (3/4 in) sieve while the total gravel 4.75mm (No.4) to 75mm (3 in) fraction remains the same. While traditionally this method of specimen preparation has been used to avoid the error inherent in testing materials containing large particles in the CBR test apparatus, the modified material may have significantly different strength properties than the original material. However, a large experience base has developed using this test method for materials foe which the gradation has been modified and satisfactory design methods are in use based on the results of using this procedure.

1.3. Past practice has shown that CBR results for those materials having substantial percentages of particles retained on the 4.75mm (No.4) sieve are more variable than for finer materials. Consequently, more trials may be required for these materials to establish a reliable CBR.

1.4. This test method provides for the determination of the CBR of a material at optimum water content or a range of water content from a specified compaction test and a specified dry unit mass. The dry unit mass is usually given as a percentage of maximum dry unit mass from the compaction tests of T 99 or T180.

1.5. The agency requesting the test shall specify the water content or range of water content and the dry unit mass for which the CBR is desired.

1.6. Unless specified otherwise by the requesting agency, or unless it has been shown to have no effect on test results for the material being tested, all specimens shall be soaked prior to penetration.

1.7. The value stated in SI units are to be regarded as the standard.
 
2.  REFERENCED DOCUMENTS

AASHTO Standards:

2.1. T 99, Moisture-Density Relations of Soils Using a 2.5 kg (5.5 lb.) Rammer and a 305-mm (12-in) Drop

2.2. T 180, Moisture-Density Relations of Soils using a 4.54 kg (10-ib.) Rammer and a 457-mm (18-in) Drop

2.3. T 265, Laboratory Determination of Moisture Content of Soils
 
3. SIGNIFICANCE AND USE

3.1. This test method is used to evaluate the potential strength of subgrade, subbase and base course material, including recycled materials, for use in road and airfield pavements. The CBR value obtained in this test from an integral part of several flexible pavement design methods.

3.2. For applications where the effect of compaction water content on CBR is small, such as cohesion less, coarse-grained materials, or where an allowance is made for the effect of differing compaction water contents in the design procedure, the CBR may be determined at the optimum water content of a specified compaction effort. The dry unit mass specified is normally the minimum percent compaction allowed by using the agency's field compaction specification.

3.3. For applicators where the effect of compaction water content on CBR is unknown or where it is desired to account for its effect, the CBR is determined for a range of water content, usually the range of water content permitted for field compaction by using the agency's field compaction specification.

3.4. The criteria for test specimen preparation of self-cementing (and other) materials that gain strength with time must be based on a geotechnical engineering evolution. As directed by the engineer, self-cementing materials shall be properly cured until bearing ratios representing long-term service conditions can be measured.

For Further Detail......Read More

 

Sampling of freshly mixed concrete (ASTM 1064/M -99)

1. Sampling Concrete.

1.1 The temperature of freshly concrete may be measured in the transporting equipment provided the sensor of the temperature measuring device has at least 3 in. [75 mm] of concrete cover in all directions around it.

1.2 Temperature of the freshly mixed concrete may be obtained following concrete placement using the forms as the container.

1.3 If the transporting equipment or placement forms are not used as the container, a sample shall be prepared as follows:

1.3.1 Immediately, prior to sampling the freshly mixed concrete, dampen (with water) the sample container.

1.3.2 Sample the freshly mixed concrete in accordance with practice C 172, except that composite samples are not required if only purpose for obtaining the sample is to determine temperature.

1.3.3 Place the freshly mixed concrete into the container.

1.3.4 When concrete contains a nominal maximum size of aggregate greater than 3 in. [75 mm], it may require 20 min before the temperature is stabilized after mixing.

2. Procedure.

2.1 Place the temperature measuring device in the freshly mixed concrete so that the temperature sensing portion is submerged a minimum of 3 in. [75 mm]. Gently press the concrete around the temperature measuring device at the surface of the concrete so that ambient air temperature does not affect the reading,

2.2 Leave the temperature measuring device in the freshly mixed concrete for a minimum period of 2 min or until the temperature reading stabilizes, then read and record the temperature.

2.3 Complete the temperature measurement of the freshly mixed concrete within 5 min after obtaining the sample.

3. Report.

3.1 Record the measured temperature of the freshly mixed concrete to the nearest 1°F [0.5°C].

4 Precision and Bias.

4.1 The precision and bias of this test method have not been determined. A precision and bias statement will be included when sufficient test data have been obtained and analyzed.

Calibration of Temperature Measuring Device (ASTM Standard)

 Apparatus:

4.1 Container, shall be made of no absorptive material and large enough to provide at least 3 in {75 mm} of concrete in all directions around the sensor of the temperature measuring device; concrete cover must also be at least three times the nominal maximum size of the coarse aggregate.

4.2 Temperature Measuring Device, shall be capable of accurately measuring the temperature of the freshly mixed concrete to ± 1°F [±0.5°C] throughout a range of 30°to120°F [0° to 50°C]. The temperature measuring device shall require immersion of 3 in {75 mm} or less during operation.

4.3 Partial immersion liquid-in-glass thermometers (and possibly other types) shall have a permanent mark to which the device must be immersed without applying a correction factor.

4.4 Reference Temperature Measuring Device, shall be readable and accurate to ±0.5°F [0.2°C] at the verification points in 5.1. A certificate or report that verifies the accuracy shall be available in the laboratory for review. The certificate or report shall provide documentation that the reference standard used in the verification is traceable to NIST.

5. Calibration of Temperature Measuring Device   

5.1 Each temperature measuring device used for determining temperature of freshly mixed concrete shall be calibrated annually, or whenever there is a question of accuracy. This calibration shall be performed by comparing the readings of the temperature measuring device at two temperatures at least 30°F [15°C] apart.

5.2 Calibration of the temperature measuring device may be made in oil or other suitable baths having uniform density if provision is made to:

5.2.1 Maintain the bath temperature constant within 0.5°F [0.2°C] during the period of the test.

5.2.2 Have both the temperature and reference temperature measuring device maintained in the both for a minimum of 5 min before reading temperatures.

5.2.3 Continuously circulate the bath liquid to provide a uniform temperature.

5.2.4 Slightly tap thermometers containing liquid to avoid adhesion of the liquid to the glass if the temperature exposure is being reduced.

Apparatus:

4.1 Container, shall be made of no absorptive material and large enough to provide at least 3 in {75 mm} of concrete in all directions around the sensor of the temperature measuring device; concrete cover must also be at least three times the nominal maximum size of the coarse aggregate.

4.2 Temperature Measuring Device, shall be capable of accurately measuring the temperature of the freshly mixed concrete to ± 1°F [±0.5°C] throughout a range of 30°to120°F [0° to 50°C]. The temperature measuring device shall require immersion of 3 in {75 mm} or less during operation.

4.3 Partial immersion liquid-in-glass thermometers (and possibly other types) shall have a permanent mark to which the device must be immersed without applying a correction factor.

4.4 Reference Temperature Measuring Device, shall be readable and accurate to ±0.5°F [0.2°C] at the verification points in 5.1. A certificate or report that verifies the accuracy shall be available in the laboratory for review. The certificate or report shall provide documentation that the reference standard used in the verification is traceable to NIST.

5. Calibration of Temperature Measuring Device   

5.1 Each temperature measuring device used for determining temperature of freshly mixed concrete shall be calibrated annually, or whenever there is a question of accuracy. This calibration shall be performed by comparing the readings of the temperature measuring device at two temperatures at least 30°F [15°C] apart.

5.2 Calibration of the temperature measuring device may be made in oil or other suitable baths having uniform density if provision is made to:

5.2.1 Maintain the bath temperature constant within 0.5°F [0.2°C] during the period of the test.

5.2.2 Have both the temperature and reference temperature measuring device maintained in the both for a minimum of 5 min before reading temperatures.

5.2.3 Continuously circulate the bath liquid to provide a uniform temperature.

5.2.4 Slightly tap thermometers containing liquid to avoid adhesion of the liquid to the glass if the temperature exposure is being reduced.

Standard Test Method for Temperature of Freshly Mixed Portland Cement Concrete

 

Scope

This test method covers the determination of temperature of freshly mixed Portland cement concrete.

The values stated in inch-pound or SI unit are to be regarded separately as standard. Within the text, SI unit are show in brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.

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.

Referenced Documents

ASTM Standards:

C 172 Practice for Sampling Freshly Mixed Concrete

Significance and Use

This test method provides a means for measuring the temperature of freshly mixed concrete. It may be used to verify conformance to a specified requirement for temperature of concrete.

Concrete containing aggregate of a nominal maximum size greater than 3 in. [75 mm] may require up to 20 min for the transfer of heat from aggregate to mortar. (See ACI Committee 207. IR Report)   

AASHTO, ASTM, BS Standard Code

Test Description	Applicable Standard
Sieve Analysis	AASHTO  T88  &  M124 , AASHTO T27 and T11,BS 1377: part 2 test 9.2
Liquid Limit	AASHTO T89
Plasticity Index PI	AASHTO T90
CBR	AASHTO T193 ,BS 1377 part 4 test 16 ,  (ASTM D 1883)
FDT	AASHTO T191 ,BS 1377 part 9 test  2.2
Maximum Dry Density	AASHTO T180
Sand Equivalent	AASHTO T176,ASTM C-88
Loss by Abrasion	AASHTO T96
Soundness(Sodium)	AASHTO T104
Soundness(Magneseum)	AASHTO T104
Ave. Compressive Strength	BS 1881
Mean water absorption of cubes	BS EN 1340
Rate of Application	ASTM D2995
Absorption	AASHTO T85
Specific Gravity	AASHTO T85
Marshall Properties
Number of compaction blows each end of specimen by freely held marshall hammer	AASHTO T-245
Stability(Marshall) Minimum ,Kg
Flow(Marshall),mm
Stiffness Minimum Kg/mm (minimum)
Percent air void in Mix
Percent air void in mineral aggregates, minimum % (V.M.A.)
Percent voids filled with asphalt cement %
Bitumen Content %
Loss of Marshall Stability by submerging specimen in water at 600C for 24hrs. As compared to stability measured after submersion in water at 600C for 30 mins.
Residual voids in total mix after 300 blows each end of specimen
Filler to Bitumen ration
Compaction of laid Asphalt Concrete	AASHTO T-166
Thickness laid Asphalt Concrete	AASHTO T-166
Slump	ASTM C-143 /AASHTO T 119M
Concrete Temperature	ASTMC-1064/BS 1881-130/ASTM 1064/M -99
Compressive Strength @ 7 & 28 Days	BS 1881
Water Absorption@ 28D	BS 1881-122:2011
Rapid Chloride Permeability @ 28D	AASHTO T277/ASTM C-1202
Water penetration@ 28D	DIN 1048-5:1991-06.
Initial Surface Absorption test(ISAT)@28D	BS 1881-208:1996
Shrinkage Test at @ 28D	BS 1881-122:2011