Grain-Size Analysis of Soil (Including Both Mechanical and Hydrometer Analyses) - Soil Properties: Testing, Measurement, and Evaluation - page 130

The specific gravity of the soil particles G was determined by a pre-
vious test to be 2.70.
The calculations for this example follow the steps outlined in the
preceding section. A form prepared for recording both initial data and
computed results is given on pages 133 to 135. (At the end of the chapter,
two blank copies of this form are included for the reader's use.) The reader
is referred to both the steps in the section “Calculations” and the form on
pages 133 to 135 to help in understanding the calculations that follow.

1. Percentage of sample retained on No. 10 sieve (2.20/540.94)

×

100 0.4%.
2. Percentage of sample passing through No. 10 sieve 100 - 0.4 99.6%.
3. For the 3 ⁄ 8 -in. sieve, none of the sample is retained; hence, the mass
passed is 540.94 g, and the total percentage passed is 100. For the
No. 4 sieve, 0.97 g is retained; hence, the mass passed is 540.94 -
0.97, or 539.97 g, and the total percentage passed is (539.97/ 540.94 )
×

100, or 99.8%. For the No. 10 sieve, 0.97 + 1.23, or 2.20 g, is re-
tained; hence the mass passed is 540.94 - 2.20, or 538.74 g, and the
total percentage passed is (538.74/ 540.94 ) 100, or 99.6%.

×

4. Hygroscopic moisture correction factor =

108.85 59.57
109.57

0.9856

59.57

5. The mass of the air-dried sample for hydrometer analysis is 170.49
- 110.21, or 60.28 g. Hence, the calculated mass of the total oven-
dried hydrometer analysis sample can be computed as follows:

60.28 0.9856

1 21 2

M 100 59.65 g

99.6

6. For the No. 10 sieve, none of the sample is retained; the mass passed
is ( 170.49 - 110.21 ) 0.9856, or 59.41 g, and the total percentage

×

passed is (59.41/59.65) 100, or 99.6%. For the No. 40 sieve, 5.13 g

is retained; hence, the mass passed is 59.41 - 5.13, or 54.28 g, and
the total percentage passed is (54.28/59.65)

×

100, or 91.0%. For the
No. 100 sieve, 5.13 + 5.31, or 10.44 g, is retained; hence, the mass
passed is 59.41 - 10.44, or 48.97 g, and the total percentage passed
is (48.97/59.65)

×

100, or 82.1%. The computation for the No. 200
sieve is done in the same manner.
7. For this hydrometer analysis, a composite correction of 0.002 at
20°C was determined. For the 8:32 A . M . time, for which elapsed time
is 2 min, the corrected hydrometer reading is 1.026 - 0.002, or 1.024.
The percentage of soil remaining in suspension can be computed us-
ing Eq. (10-1) (because the 151H hydrometer is being used):

×

c 1

100,000 > M 2 G

P d1 R G 1 2 (10-1)

G G 1

In this application, M is 59.65 g (see step 5), G is 2.70 (known value
from a previous specific gravity test), G 1 is taken to be 1, and R , the