This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Factors Affecting Compaction”.
1. Which of the following factors affects compacted density?
a) Water content and Type of compaction
b) Degree of saturation
c) None of the mentioned
d) All of the mentioned
View Answer
Explanation: Water content, type of soil, addition of admixtures, amount and type of compaction are the various factors which affect the compacted density.
2. The compacted density is increased when the water content of the soil is _________
a) Increased
b) Decreased
c) Constant
d) None of the mentioned
View Answer
Explanation: It has been seen from a laboratory experiment that, as the water content is increased the compact density goes on increasing, until a maximum dry density is achieved after which further addition of water decreases the density.
3. The force which is responsible for withholding of soil particles, of lower content is __________
a) Vander Waals force
b) Electric force
c) Frictional force
d) Cationic linkage
View Answer
Explanation: When only a relatively small amount of water is present in the soil, it is firmly held by the electrical forces at the surface of soil particles with a high concentration of the electrolyte.
4. The amount of compaction greatly affects ___________
a) Water content and Maximum dry density
b) Saturation of soil
c) None of the mentioned
d) All of the mentioned
View Answer
Explanation: The amount of compaction affects maximum dry density and optimum water content of a given soil. The effect of increasing the compactive energy results in an increase in the maximum dry density and decrease in the optimum water content.
5. Higher density and lower optimum water content is easily achieved by _________
a) Coarse grained soil
b) Fine grained soil
c) Cohesion less soil
d) Saturated soil
View Answer
Explanation: Well graded coarse-grained soil attains a much higher density and lower water optimum water content then fine grained soil which requires more water.
6. The dry density decreases in cohesion less soil with an increase in water content due to which of the following reasons?
a) Capillary rise
b) Bulking of sand
c) Degree of saturation
d) Water content
View Answer
Explanation: In case of cohesion less soil the dry density decreases with an increase in water content under a low compactive effect, this is due to bulking of sands where in the capillary tension resists the tendency of soil particles to take a density state.
7. The maximum density is reached in cohesion less soil when the soil is _________
a) Zero water content
b) Partially saturated
c) Fully saturated
d) Maximum specific surface
View Answer
Explanation: The density reaches the maximum value when the cohesion less soil is fully saturated, on further addition of water, the dry density again increases.
8. The maximum bulking of sand occurs at a water content between ___________
a) 4 to 5 %
b) 2 to 6 %
c) 4 to 8 %
d) 1 to 5 %
View Answer
Explanation: The maximum bulking occurs at water content between 4 to 5 %. On further additions of water, the meniscus is destroyed and the soil particles are able to shift to a closer packing.
9. The initial decrease of dry density at lower water content is exhibited in ____________ type of soil.
a) Fine grained soil
b) Black cotton soil
c) Alluvial soil
d) Cohesion soil
View Answer
Explanation: The initial decrease of dry density at lower water content is a characteristic feature of black cotton soils, high swelling clays and fat clays. The optimum water content for such soils ranges between 20 to 25%.
10. The attainment of maximum density of soil at full saturation is due to __________
a) Lubrication action
b) Hydrostatic pressure
c) Bulking of sand
d) None of the mentioned
View Answer
Explanation: The attainment of maximum density at full saturation is due to the reduction of effective pressure between soil particles by hydrostatic pressure.
Sanfoundry Global Education & Learning Series – Geotechnical Engineering.
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