Sep 14, 2017 · What are the typical CBR values? The harder the material, the higher the CBR value. A CBR value of 2% is usually found for clay, high-quality sub-base will have CBR values between 80% and 100%, and some sands may have values around 10%.

The California Bearing Ratio (CBR) test is a simple strength test that compares the bearing capacity of a material with that of a well-graded crushed stone (thus, a high quality crushed stone material should have a CBR @ 100%).

CBR values provide a quantified estimate of soil strength and surface stiffness suitable for use in road foundation design. Understanding CBR values helps in determining the CBR value of soil and its appropriateness for construction purposes.

CBR values for common soil subgrades can be estimated according to the USC soil types, for example: clay around 2%, sand from 7% (poorly graded) to 10% (well graded), well graded sandy gravel 15%, clayey sand 5-20%, silty gravel 20-60%, gravel from 30-60% poorly-graded to 40-80% if well-graded.

CBR Values. California bearing ratios of field tests represent in-situ strengths of the material under existing field conditions and will not typically correlate with laboratory CBR values of the same material. Saturation levels are near 100% for soaked laboratory samples.

Dec 2, 2024 · The California Bearing Ratio (CBR) is described as the ratio of the force per unit area needed to penetrate a soil mass using a standard circular plunger with a diameter of 50 mm, at a consistent rate of 1.25 mm/min, to that needed …

California bearing ratio test (CBR) is defined as the ratio force per unit area which is required to penetrate a mass of soil with the standard circular piston at a rate of 1.25 millimeters per minute to that required for corresponding penetration of standard material.

Feb 3, 2020 · California Bearing Ratio (CBR) is a penetration test for evaluation of the mechanical strength of road subgrades, sub-base and base courses. It was developed by the California Department of Transportation. The test is performed by measuring the pressure required to penetrate a soil sample with a plunger of standard area.

CBR = (Force to penetrate soil / Force to penetrate preferred material) x 100. A typical range of CBR values for different soil types is as follows: Highly compacted gravel or rock: CBR > 80%; Sandy or gravelly soils: CBR between 10% and 80%; Silty or clayey soils: CBR < 10%; Conclusion

Aug 5, 2024 · California Bearing Ratio (CBR) testing is a reliable measure of soil strength and stiffness used for pavement design. The California Bearing Ratio test uses lab and field methods. It calculates soil resistance, classifies soils, and assesses foundation stability.