Question by Romeo P: what is the meaning of cbr in soil test?
Answer by avecverve
California Bearing Ratio.
The test was developed by Caltrans (California Dept. of Transportation). The test measures the mechanical strength of soil to be used as subgrade for asphalt road.
You use a standardized “hammer” (i.e. a rod with a pounding surface on the bottom) to try to penetrate the surface of a soil. You take the pressure it takes to penetrate this soil and divide it by the pressure it takes to penetrate a certain type of crushed limestone. You multiply that ration by 100.
So, something that has a CBR of 4 or 5 would be soft, muddy, like jello. Something that has a CBR of 80 would be excellent to use for roadway subgrade.
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