The California Bearing Ratio (CBR) field test measures the relative strength of in–situ soils and some base course materials for use in pavement design. The field test procedure uses a loading jack to force a piston into the soil at the test site and comparing the piston load to the depth of penetration. The jack is loaded against dead weights or a heavy piece of equipment such as a loaded dump truck.
Field CBR apparatus are ordered individually for tests performed according to ASTM or Army Corps of Engineers (C.O.E.) test methods. Additional surcharge masses may be needed to simulate large pavement loads. Components are available individually or as a set with either a two-speed or three-speed jack that conforms to ASTM and C.O.E.