Determining Moisture-Unit Weight Relations of Soil (Compaction Test) - Soil Properties: Testing, Measurement, and Evaluation - page 179

[B] Moisture Content Data

Mass of container, M c 45.20 g

Mass of container plus moist soil, M cws 235.65 g

Mass of container plus oven - dried soil, M cs 210.38 g

These data for the first trial specimen of the compaction test, together
with the data for all succeeding trial specimens, are presented on the
form on page 181. At the end of the chapter, two blank copies of this form
are included for the reader's use.
The moisture content, computed using Eq. (4-2), was determined to
be 15.3%. The unit weights can be computed as follows:

M t M md

1000 V

(12-1)

r m

3.718 1.990

m 3

r m 1.831 Mg >

1000 0.0009438

1 21 2

r m

(12-2)

r d

w
100

1

1.831

1.588 Mg m

r d

100

>

1 15.3 >

62.43 1.831 114.3 lb ft 3

g wet 1 21 2 >

ft 3 62.43 1.588 99.1 lb

g d 1 21 2 >

These values are presented on the first line of the form on page 181.
Similar calculations for the four remaining trial specimens were made,
and the results are also given on the form.
(In using the form on page 181 the reader will note that columns B,
C, F, G, H, and J contain data that were obtained during the test. Other
columns contain values computed from test data. A key for facilitating
computation of these values is given at the bottom of the form.)
The moisture-unit weight relationship (compaction curve) is ob-
tained by plotting a graph of dry unit weight versus moisture content,
as shown in Figure 12-6. (At the end of the text a copy of the blank
graph form is included and may be photocopied as needed.) From this
graph, the optimum moisture content is determined to be 20.7% and the
maximum dry unit weight is 104.8 lb/ft 3 .