Figure 15-21.-Potecting a sample in a CBR mold.
Figure 15-22.-Halving the sample.
shown in figure 15-21. If the samples are to be
transported some distance or will be handled quite
a bit before testing, you should wrap them in cloth
and soak them in paraffin layers.
QUARTERING SAMPLES
The process of reducing a representative soil
sample to a convenient size or of dividing a sam-
ple into two or more smaller samples for testing
is called QUARTERING. The procedures vary
somewhat, depending upon the size of the sample.
Samples Weighing Over 100 Pounds
To quarter a sample of this size, first mix and
pile the sample on a canvas, using a shovel. Place
each new shovelful on the top-center of the
preceding one so that the soil will be distributed
evenly in all directions. Then flatten the sample
to a circular layer of approximately uniform
thickness. Next, insert a stick or length of pipe
under the canvas and then lift it at both ends to
divide the sample into two equal parts, as shown
in figure 15-22. Remove the stick, leaving a fold
in the canvas, and then reinsert it under the sam-
ple, but this time, at right angles to the first divi-
sion. Again, lift the stick. This divides the
sample into four parts, as shown in figure 15-23.
Discard two diagonally opposite quarters, taking
care to clean the fines from the canvas. Then
remix the remaining material, taking alternate
shovelful from each quarter. Repeat the quarter-
ing process as necessary to reduce the sample to
the desired size.
Samples Weighing Between
25 and 100 Pounds
In quartering a sample of this size, pile the soil
on the canvas and mix it by alternately lifting the
Figure 15-23.-Quartering the sample.
15-16
