California Bearing Ratio Test - Soil Properties: Testing, Measurement, and Evaluation - page 401

Figure 24-3 Correction of Curves of Penetration Stress versus Penetration [1]

(from the curve of penetration stress versus penetration) by the stan-
dard penetration stress of 1,000 psi and multiplying by 100 (to express
the answer as a percentage). [This is the application of Eq. (24-1).] The
bearing ratio at 0.20-in. penetration is determined similarly, using the
corrected penetration stress (psi) on the piston for 0.20-in. penetration
and a standard penetration stress of 1,500 psi. If the bearing ratio
based on 0.20-in. penetration is larger, the test should be rerun. If the
retest gives a similar result, the ratio based on the 0.20-in. penetration
should be reported as the CBR. Otherwise, the ratio based on 0.10-in.
penetration should be the reported CBR value.