California Bearing Ratio Test Apparatus

It defines the relative bearing ratio and expansion characteristics under known surcharge weight of base, sub-base, and sub-grade soils for the design of pavements, roads, and runways. The CBR test is used widely in the control of sub-grades and selection of materials.It is the ratio of force per unit area required to penetrate a soil mass with standard circular piston at the rate of 1.25 mm/min. to that required for the corresponding penetration of a standard material. C.B.R. = Test load/Standard load 100.