Standard method of test for the california bearing ratio aashto designation. The california bearing ratio test is penetration test meant for the evaluation of subgrade strength of roads and pavements. In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to. The cbr test forms part of the site investigation and is used to determine the thickness of materials needed for the proposed road construction. Align the surcharge weight with the plunger so that the plunger penetrates freely in to the soil. California bearing ratio cbr test of subgrade soil procedure, apparatus, and use for pavement design 5 months ago cementconcrete the california bearing ratio test cbr test is a penetration test that can be performed in the laboratory or insitu. The california bearing ratiocbr test is a measure of resistance of a material to penetration of standard plunger under controlled. California bearing ratio typical values cbr testing uk. In this study, california bearing ratio cbr tests were undertaken on cape flats sand samples randomly mixed with plastic strips to form composite specimens. The test is basically performed by measuring the pressure needed to penetrate a soil with a piston of standard area.
Pdf evaluation of soil bearing capacity by plate load. California bearing ratio cbr test engineering discoveries. Therefore, for these types of soils california bearing ratio could be used as a method of. Pdf correlation of california bearing ratio cbr value. Effect of california bearing ratio on the properties of soil. Cbr is an index is used to assess the stiffness modulus and shear strength of a material by measuring its resistance to penetration of a standard plunger under controlled density and moisture conditions. The cbr testing can be applied to soils with a maximum particle size of 20 mm. For soils with bigger particles, other types of bearing capacity can be used like the plate bearing test. The california bearing ratio cbr is a penetration test for evaluation of the mechanical strength of road sub grades and base courses. What are the difference between tender and contract documents. It is a penetration test in which a standard piston, with a diameter of 50 mm 1. The accurate estimation of soil bearing capacity plays an important role in the design of a stable foundation for road pavement and airfields projects. Method of compaction under the original california test method of.
To determine the amount of water present in a soil expressed as a percent age of the mass of dry. An improved california bearing ratio test procedure. This laboratory test is based on penetration resistance of a soil to a standardsized piston. This lecture includes following topics tests on soil in highway engineering most important tests cbr test aim of cbr test procedure of cbr test formula for finding cbr value graphs in cbr test. Interpretation of soil classification at different cbr ith bearing capacity packard, 1973 9th sayge conference 2017 278 figure 6. California bearing ratio cbr tests on soil reinforced. T 265, laboratory determination of moisture content of soils. This test method covers the determination of the california bearing ratio cbr of pavement subgrade, subbase, and basecourse materials from laboratory compacted specimens. The cbr test is essentially a laboratory test but in some instances the test is carried out on the soil. Falling head method 37 8 determination of optimum moisture content and maximum dry density of soil by proctor test 46 california bearing ration test 49 consolidation test 54 11. The ratio is usually determined for penetration of 2. Cbr value can be measured directly in the laboratory in accordance with is 2720 part 16 on soil samples acquired from site.
In the lab, soils at specific moisture contents are compacted into molds. Test which is an ad hoc penetration test developed by the california state highways dept. Effect of soaking period of clay on its california bearing ratio value. Hence, an attempt was made to use the proctor mold itself with a proportionately smaller plunger to estimate the cbr values. Ratio cbr is a penetration test performed on a soil in order to evaluate its mechanical strength.
Soil sample the material used in the remoulded specimen should all pass through a 19 mm is sieve. The ultimate inplace cbr, or stability, depends on a the method of compaction, b the ultimate density, c the ultimate maximum or equilibrium moisture, and d any structural effects developed in the soil with time. The california bearing ratio test is penetration test meant for the evaluation of. This test method covers the determination of the california bearing ratio cbr of pavement subgrade, subbase. If it is proposed to carry out the cbr test on a soaked specimen, the moisture content for remoulding should be at the optimum and soaked under water for 96 hours. Lab report on cbr compaction test report2 department of civil engineering oklahoma state university submitted by. Therefore, for such materials the california bearing ratio cbr could be used as a method of compaction assessment and an indicator of soil bearing capacity. For test for soil determination of revision eworii cbr 0. Due to the large volume of soil sample material and effort involved, the conventional california bearing ratio cbr tests are laborious and time consuming. The cbr test is performed by measuring the pressure required to penetrate a soil sample with a plunger of standard area.
Laboratory test takes at least four days to measure the cbr value for each soil sample. The cbr test could be used for running compaction control during. Hardware complete drawings of the dcp are given in figures 1 through 6 at the back of this publication. This sampling method was not viable for the more granular materials, and so the cbr test specimens for these were prepared in the laboratory. The california bearing ratio cbr test is a measure of resistance of a material to penetration of standard plunger under controlled density and moisture it was developed by the california division of highways as a method of classifying and evaluating soil subgrade and base course materials for flexible pavements. The material passing the 19mm sieve is split up for determining maximum dried density, optimum moisture content and cbr. California bearing ratio test on subgrade soil procedure and. An improved california bearing ratio test procedure colin a. Pdf california bearing ratio test simplified researchgate. Standard test method for cbr california bearing ratio of laboratorycompacted. Stabilization of subgrade soil using additives a case study. The interpretation of tests result such as effects of fiber content, length of fiber and diameter of fiber on cbr value of soil have been discussed in the following sections.
Test results and discussions the cbr values of soil and soil reinforced with different combinations of jute fiber determined in the laboratory are shown in table 3. Among the various methods of determining the strength of subgrade the cbr test is very important. It is mainly usedto test granular materials in base, subbase and subgrade layers of roads and airfield pavements alamoudi et al. Pdf due to the large volume of soil sample material and effort involved, the conventional california bearing ratio cbr tests are laborious. Engaged in the testing andor inspection of soil and rock as used in engineering design and construction2 d 4318 test method for liquid limit, plastic limit, and plasticity index of soils2 d 4429 test method for cbr california bearing ratios of soils in place2 3. Report the cbr value to the nearest second decimal. The great value of this test is that it is comparatively easy to perform and because of its wide use throughout the world, there is a vast amount of data to assist with the interpretation of results. Modified cbr tests on geosynthetic reinforced soil aggregate systems 299 where e s is the standard compaction energy in kj m3 592, n b is the number of blows per lift, n l is the number of lifts, w is the weight of the rammer used in kn 4. Wayne lee the california bearing ratio cbr test is one of the most common strength tests conducted to evaluate subgrade quality of soils and the suitability of soils for sub base and base courses in pavements. The california bearing ratio cbr test yields relative strength of laboratorycompacted or in situ soils and base course materials. A california bearing ratio cbr test is run on soils to gauge the strength of the subgrade as compared to a dense graded aggregate. Standard test method for cbr california bearing ratio of. Plate load test is one of the quick, direct and economic methods for soil bearing capacity.
The cbr test is essentially a laboratory test but in some instances the test is carried out on the soil insitu. It is a measure of the shearing resistance of a soil to penetration under controlled density and moisture conditions. Equipments apparatus compression machine proving ring, dial gauge, timer sampling tube split mould vernier caliper, balance preparation sample the test may be performed a on undisturbed soil specimen. The test is basically performed by measuring the pressure needed to penetrate a soil. Objective cbr is the ratio expressed in percentage of force per unit area required to penetrate a soil mass with a standard circular plunger of 50 mm diameter at the rate of 1. A test to provide data on the compaction characteristics of soil was.
Can one use the dynamic cone penetrometer to predict the. Modified cbr tests on geosynthetic reinforced soil. Take the average of three test specimens as the cbr value of the test. Cbr is the ratio, expressed in percentage of force per unit area required to penetrate a soil mass with a standard circular plunger of 50 mm diameter at the rate of 1. The cbr test is one of the most commonly used methods to evaluate the strength of a sub grade soil, sub base, and base course material for design of thickness for highways and airfield pavement. California bearing ratio cbr test is run on soils to gauge the strength of the subgrade as compared to a dense graded aggregate. Each soil sample was first subjected to proctor test in order to find its optimum moisture content which will be used to perform the cbr test. The correlation between the cbr value and penetrability of. California bearing ratio test on subgrade soil procedure.
The california bearing ratio cbr test is one of the most common strength tests conducted to evaluate subgrade quality of soils and the suitability of soils. The uts0854 is designed to load the penetration piston into the soil sample at a constant rate to measure the applied load and. The cbr test can also be used to get the curve of the loadsettlement of the soil in the field which is more or less similar to the plate load test objective. Cbr test procedure california bearing ratio for road design. Objective determination of cbr of soil either in undisturbed or remoulded condition reference standards is. A cbr value of 2% is usually found for clay, highquality subbase will have cbr values between 80% and 100%, and some sands may have values around 10%. This will determine the size of mould to be used in the cbr test. Correlation of california bearing ratio cbr value with soil properties of road subgrade soil article pdf available in geotechnical and geological engineering june 2018 with 8,574 reads.
Cbr versus bearing pressure packard 1973 is derived from various plate load test undertaken on materials with various cbr values and the bearing capacity measured at 2. Standard laboratory method for a remoulded specimen. Omc of the soil and california bearing ratio cbr test to determine the maximum penetration load that the samples could withstand before deformation under soaked conditions with the nonwoven geotextile reinforced in the soil samplesat depths h4 from the top and bottom surfaces of the soil in the cbr. The design of flexible pavement takes into account some important parameters such as traffic load, material properties of layers and sub grade soil. The soil is sieved over a 19mm sieve and the percentage of sample remaining on the sieve is calculated.
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