Humboldt H-4165 Harvard Miniature Compaction Apparatus - Manual (Page 3)

making one complete coverage. This cycle is then repeated until the desired number
of tamps has been applied. The tamps should be applied at the approximate rate of 10
tamps per 15 sec.
3. Add the next layer and repeat the procedure until the required number of compacted
layers has been placed. The top layer should extend at least ½ in. into the extension
collar.
4. Remove mold from clamp. Insert spacer disc in collar remover and ejector. Place mold
into device with lugs on the remover in the groove provided in the collar. Press down
firmly on the piston and on the lever arm at the back, prying the collar free of the
compacted soil.
5. Remove the mold from the base and carefully trim away the excess soil from the top of
the mold and from the bottom, if any.
6. Weigh the mold containing the compacted soil to the nearest 0.1g. It is convenient
to use a rare weight equal to the weight of the empty mold, as then the resulting net
weight in grams is numerically equal to the wet unit weight of the compacted soil, in
pounds per cubic foot.
7. Remove the specimen from the mold with the sample ejector and place in a suitable
container for drying and determination of moisture content.
8. Compact additional specimens until points have been established on both sides of the
optimum moisture content.
Calculations
Calculate the moisture content and the dry weight of the soil as compacted for each trial,
as follows:
w = ___A – B___ X 100
B – C
And
W = ___W1___ __ X 100
W + 100
Where:
w = Percentage of moisture in the specimen
A = weight of container and wet soil
B = weight of container and dried soil,
C = weight of container
W = dry weight, in pounds per cubic foot of compacted soil and
w1 = wet weight, in pounds per cubic foot