Determining the Density and Unit Weight of Soil in Place by the Rubber-Balloon Method - Soil Properties: Testing, Measurement, and Evaluation - page 219

Surcharge load
Initial reading of volume indicator
Final reading of volume indicator

[B] Field Data

Initial reading of volume indicator on rubber-balloon apparatus
Final reading of volume indicator on rubber-balloon apparatus
Mass of pan
Mass of pan plus all moist soil from test hole
Data for moisture content determination
Mass of container
Mass of container plus moist weight of moisture sample
Mass of container plus dry weight of moisture sample

Note— These data for moisture content determination would not be
collected if the moisture content is determined using a calcium carbide
gas pressure tester (Chapter 13).

CALCULATIONS [A] Calibration of Balloon Apparatus

Calculate the volume of the calibration containers or molds from Eq.(15-1).

[B] Field Data

The volume of the test hole, V h , can be determined by subtracting the
initial volume indicator reading on the rubber-balloon apparatus from
the final reading. The mass of all moist soil from the test hole, M wet , can
be computed by subtracting the mass of the pan from the mass of the
pan plus moist soil. The (in-place) wet density,

wet , can then be found

using the equation

M wet
V h

(15-2)

wet

If M wet is in grams and V h in cubic centimeters,

wet will be in grams
per cubic centimeter. To get (in-place) wet unit weight,

wet , in pounds

per cubic foot, merely multiply by 62.427.
The moisture content, w, can be determined in the usual manner
[see Eq. (14-4)] and (in-place) dry unit weight,

d , can be computed

using the equation

g wet

w + 10 * 100

(15-3)

g d =