Problems on Compaction of Soil
1. An earth embankment is compacted at a water content of 18% to a bulk density of 19.2 kN/m3. If
the specific gravity of the sand is 2.7, find the void ratio and the degree of saturation of the
compacted embankment.
2. A moist soil sample compacted into a mould of 1000 cm3 capacity and weight 35 N, weighs53.5 N
with the mould. A representative sample of soil taken from it has an initial weight of 0.187 N and
even dry weight of 0.1691 N. Determine (a) water content, (b) wet density, (c) dry density, (d) void
ratio and (e) degree of saturation of sample. If the soil sample is so compressed as to have all air
expelled, what will be the new volume and new dry density?
3. The soil in a borrow pit has a void ratio of 0.90. A fill-in-place volume of 20,000 m3 is to be
constructed with an in-place dry density of 18.84 kN/m3. If the owner of borrow area is to be
compensated at Rs. 1.50 per cubic metre of excavation, determine the cost of compensation.
4. A soil in the borrow pit is at a dry density of 17 kN/m3 with a moisture content of 10%. The soil is
excavated from this pit and compacted in an embankment to a dry density of 18 kN/m3 with a
moisture content of 15%. Compute the quantity of soil to be excavated from the borrow pit and the
amount of water to be added for 100 m3 of compacted soil in the embankment.
5. A laboratory compaction test on a soil having G = 2.68 gave a maximum dry density of 17.85
kN/m3 and the moisture content 17%. Find the degree of saturation, air content and percentage of
air voids at the maximum dry density. Also find the theoretical maximum dry density with respect
to air voids at OMC
6. The following data have been obtained in a standard laboratory Proctor compaction test on glacial
till:
Water content % 5.02 8.81 11.25 13.05 14.40 19.25
Weight of container
35.8
and compacted soil 37.30 39.32 40.00 40.07 39.07
0
(N)
The specific gravity of the soil particles is 2.77. The container is 9.44 cm3 in volume and
its weight is 19.78 N. Plot the compaction curve and determine the optimum moisture content.
Also compute the void ratio and degree of saturation at optimum condition.
7. Given standard soil compaction test results as follows:
Moisture content % by Wet unit weight of compacted
Trial No
dry weight soil (kN/m3)
1 8.3 19.8
2 10.5 21.3
3 11.3 21.6
4 13.4 21.2
5 13.8 20.8
The specific gravity of the soil particles is 2.65.
Plot the following:
(a) Moisture-dry density curve,
(b) Zero air voids curve, and
(c) Ten per cent air content curve. (90% Saturation curve)
Determine the optimum moisture content and the corresponding maximum dry density of the soil.
8. The results of a compaction test on a soil are set out below.
Moisture Content (%) 9 10.2 12.5 13.4 14.8 16
3
Bulk unit weight (kN/m ) 19.23 20.51 22.2 22.2 21.79 20.96
Plot the dry unit weight - moisture content curve and determine the maximum dry unit weight and
corresponding optimum moisture content. If the particle specific gravity is 2.68, determine the air
void percentage at maximum dry unit weight.
9. The following are the observations of a compaction test.
Moisture Content (%) 7.7 11.5 14.6 17.5 19.5 21.2
Weight of wet soil W (N) 16.67 18.54 19.92 19.52 19.23 18.83
If the volume of compaction mould is 950 C.C, assuming G=2.65, Draw compaction curve. Report
maximum dry unit weight and optimum moisture content (OMC). Draw 100% saturation line (zero
air voids line). What is the degree of saturation at OMC.
10. A standard proctor compaction test was conducted on a soil with G = 2.85 and following results
were obtained: Find OMC. Draw the zero air voids line. Draw 10% air voids line. Show specimen
calculations for these
Bulk unit weight, kN/m3 18.00 19.00 19.60 20.45 21.00 20.50 20.10
Water content, % 9.60 11.00 12.50 14.00 16.00 18.00 19.50
