California Bearing Ratio Test - Soil Properties: Testing, Measurement, and Evaluation - page 400

[C] Swell Data

Surcharge weight (lb)
Time and date
Dial reading

Note —These data must be obtained for the initial swell measurement
and again for the final swell measurement.

[D] Bearing Ratio Data

Weight of surcharge (lb)
Area of piston (in. 2 )
Successive proving ring dial readings for each particular penetra-
tion specified in the section “Procedure”

CALCULATIONS [A] Water Content Determination

The four moisture contents are determined by the method described in
Chapter 4.

[B] Density Determination

The two densities are determined by methods described in previous
chapters.

[C] Swell Data

The swell percentage is computed by dividing the final (swell) dial read-
ing by the initial height of the soil specimen. (This assumes an initial
dial reading of zero; if the initial reading is not zero, it should be sub-
tracted from the final reading and the difference divided by the height.)

[D] Bearing Ratio

Respective piston loads can be determined by multiplying each proving
ring dial reading by the proving ring calibration. Then each penetration
stress in pounds per square inch can be obtained by dividing piston
loads in pounds by the area of the piston (which is 3 in. 2 ). A curve of pen-
etration stress (psi) versus penetration (in.) should be prepared by plot-
ting values of penetration stress on the piston (ordinate) versus
corresponding values of penetration (abscissa), both on an arithmetic
scale. In some cases, the curve of penetration stress versus penetration
may be concave upward initially, because of surface irregularities or
other causes. In such cases, the zero point should be adjusted as shown
in Figure 24-3.
The bearing ratio at 0.10-in. penetration is determined by dividing
the corrected penetration stress (psi) on the piston for 0.10-in. penetration