<P> The California bearing ratio (CBR) is a penetration test for evaluation of the mechanical strength of natural ground, subgrades and base courses beneath new carriageway construction . It was developed by the California Department of Transportation before World War II . </P> <P> The basic site test is performed by measuring the pressure required to penetrate soil or aggregate with a plunger of standard area . The measured pressure is then divided by the pressure required to achieve an equal penetration on a standard crushed rock material . The CBR test is described in ASTM Standards D1883 - 05 (for laboratory - prepared samples) and D4429 (for soils in place in field), and AASHTO T193 . The CBR test is fully described in BS 1377: Soils for civil engineering purposes: Part 4, Compaction related tests, and in Part 9: In - situ tests . </P>

What is the meaning of cbr in soil test