Mineralogy, Compaction & Water in Soils

1. Calculate the Specific Surface Area, in m2/kg,assuming that ρS=2650 kg/m3 for the following cube side lengths:
a.)10 mm
b.) 1 mm
c.) 1 μm
d.) 1nm

2. For a granular soil, you are given γT=108pcf, Dr=82%, w=8% and GS=2.65. For this soil, if emin=0.44, what would be the dry

unit weight in the “loosest” state?

3. Standard and modified proctor compaction tests were conducted. The water content and wet density are tabulated below for a

soil with Gs =2.64.

Case A
W(%) 9.3 12.8 15.5 18.7 21.1
t (Mg/m3) 2.047 2.154 2.082 2.017 1.987

Case B
W(%) 9.3 11.8 14.3 17.6 20.8 23.0
t (Mg/m3) 1.848 1.917 2.006 2.054 2.035 1.991

a.) Plot the two compaction curves on the same graph (use spreadsheet).
b.) Determine the maximum dry density and optimum water content for each case and draw line of optimums.
c.) On the same graph, plot the 100% saturation (zero air voids) curve.

4. In a field density test using the oil method, the wet mass of the soil removed from a hole in the compacted fill was 1.61 kg.

The mass of the oil required to fill the hole was 0.81 kg. The specific gravity of oil (Goil ) is 0.9. The field water content was 26%.

The specific gravity of the soil solids (Gs) is 2.7. Calculate the dry density and degree of saturation of the compacted soil.

5. Standard compaction test on a soil resulted in a maximum dry density based on the standard of 1730 kg/m3 and an optimum water

content of 15.9%. Specifications call for the compacted dry density in the field to be at least 95% of the maximum dry density and

within  2% of the optimum water content. In a field sand cone test on the compacted material, the volume of excavated soil was 1153

cm3, and its mass was 2209 g wet and 1879 g dry. The specific gravity of the soil solids is 2.7. Determine:

a. Compacted Dry Density
b. Field water content
c. Relative compaction
d. Degree of saturation
e. Does the compacted soil meet specifications? Please show your reasoning.

6. For soil with D10 = 0.005mm, compute the theoretical height of capillary rise in meters and the capillary pressure, uc (in

kPa).
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