California Bearing Ratio (CBR) and Limerock Bearing Ratio (LBR) tests yield relative strengths of soils and base course materials based on penetration resistance. CBR values can be determined under laboratory or field conditions, while the LBR test is performed only in the laboratory.
In the lab, soil specimens at specific moisture contents are compacted into molds. Sample preparation prior to testing may include soaking and addition of surcharge weights to the molded specimens. The penetration test is carried out in a Load Frame outfitted with a Penetration Piston and other CBR test components.
CBR Field Tests measure strength of in-place soils and base course materials, providing valuable information to pavement designers while maintaining ASTM D1883 and AASHTO T 193 standards. Field tests are run by forcing a Penetration Piston into the soil with a gear-driven Jack at the test site and comparing the depth of penetration to the load. Typically, the Jack is braced against a heavy piece of equipment used for a reaction load, such as a loaded dump truck.
The Florida Limerock Bearing Ratio (LBR) FM 5-515 laboratory test was developed to evaluate limerock and other soils used for base, subgrade and embankment materials typically found in Florida. This test method shares much of the same equipment and procedures used with the laboratory CBR test.
Gilson offers a complete line of laboratory and field equipment for California Bearing Ratio (CBR) testing, and laboratory equipment for the Florida Limerock Bearing Ratio (LBR) test.