California Bearing Ratio

The California Bearing Ratio (CBR) take a look at is a easy power test that compares the bearing capability of a cloth with that of a properly-graded beaten stone (for this reason, a high quality overwhelmed stone fabric need to have a CBR @ a hundred%). It’s far normally intended for, but no longer restricted to, comparing the power of cohesive materials having maximum particle sizes much less than 19 mm (0.Seventy five in.) (AASHTO, 20001). It turned into advanced via the California department of Highways around 1930 and become subsequently followed by using severa states, counties, U.S. Federal organizations and internationally. As a result, most agency and industrial geotechnical laboratories inside the U.S. Are prepared to perform CBR checks.

The basic CBR test entails applying load to a small penetration piston at a rate of one.Three mm (0.05″) consistent with minute and recording the overall load at penetrations starting from zero.Sixty four mm (0.0.5 in.) as much as 7.Sixty two mm (0.300 in.). Determine 1 is a comic strip of a regular CBR sample.

cbr test

CBR sample
Determine 1. CBR pattern

Values obtained are inserted into the subsequent equation to acquire a CBR cost:

Values obtained are inserted into the following equation to achieve a CBR fee:

Regular Values
General Soil kind USC Soil kind CBR variety
Coarse-grained soils GW 40 – 80
GP 30 – 60
GM 20 – 60
GC 20 – forty
SW 20 – forty
SP 10 – forty
SM 10 – 40
SC five – 20
Best-grained soils ML 15 or less
CL LL 15 or less
OL 5 or much less
MH 10 or much less
CH LL > 50% 15 or less
OH five or much less

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