 California bearing ratio

The California Bearing Ratio (CBR) is a test used to evaluate the strength of subgrade soil and its suitability for supporting roads, airfields, and other structures. The test measures the ability of the soil to withstand penetration by a standard piston under controlled moisture and density conditions. The CBR test is performed by comparing the pressure required to penetrate a soil sample with that required to penetrate a standard crushed stone material. The results are expressed as a percentage.