# Soil Mechanics Questions and Answers – Compaction Introduction

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This set of Soil Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Compaction Introduction”.

1. Compaction decreases the porosity.
a) True
b) False

Explanation: Compaction is a process by which the soil particles are artificially rearranged into a closer state. This arrangement reduces the voids ratio and hence there is decrease in the porosity.

2. Dry density of soil is increased by _________
a) compaction
b) swelling
c) bulking
d) addition of excess of water

Explanation: Compaction is a process by which the soil particles are artificially rearranged into a closer state which reduces the voids ratio and hence there is decrease in the porosity. Due to this, the dry density of the soil sample is increased.

3. Which of the following does not causes compaction?
a) vibration
b) tamping
c) rolling

Explanation: When the water is added to the soil sample, it first occupies the voids present in between the soil particles. When excess of water is added to the soil sample, then swelling of the sand takes place, hence reducing its compaction.

4. In 1933, ____________ showed the existence of relationship between soil water content and degree of dry density.
a) Terzaghi
b) Skempton
c) Darcy
d) Proctor

Explanation: In 1933, Proctor showed the existence of relationship between soil water content and degree of dry density to which a soil might be compacted. Darcy is recognised for his woks in the field of permeability of the soil.

5. At Optimum water content, soil has _____
a) minimum density
b) maximum density
c) no weight
d) no density

Explanation: In 1933, Proctor showed that for a specific amount of compaction energy applied on the soil, there was a water content termed as Optimum water content at which the soil attains the maximum density.
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6. To test the compaction characteristics, the method are based on ______

Explanation: There are many methods available for the test of compaction and these tests are based on the types of compaction and these are:

• dynamic or impact
• static and vibration.

7. The Standard Proctor test was developed by ________
a) R.R. Proctor
b) Skempton
c) Darcy
d) Terzaghi

Explanation: In 1933, Proctor showed the existence of relationship between soil water content and degree of dry density to which a soil might be compacted. He developed the Standard Proctor test for the construction of the earth fill dams in the state of California.

8. In Standard Proctor test, the inside diameter of the mould is ________ inches.
a) 1
b) 4
c) 3
d) 6

Explanation: In Standard Proctor test, the test equipment is a cylindrical metal mould that has an internal diameter of 4 inches or 10.15 cm.

9. In Standard Proctor test internal effective height is ________ inches.
a) 2.3
b) 4.5
c) 4.6
d) 45

Explanation: In Standard Proctor test, the test equipment is a cylindrical metal mould that has an internal effective height of 4.6 inches or 11.7 cm.

10. In Standard Proctor test, the capacity of the mould is ________ cu.ft.
a) 1/10
b) 1/20
c) 1/30
d) 1/40

Explanation: In Standard Proctor test, the test equipment is a cylindrical metal mould that has an internal effective height of 4.6 inches and an internal diameter of 4 inches. Therefore the volume of the cylinder is, πr2 h=π*42*4.6 cu.in=$$\frac{1}{30}$$ cu.ft.

11. In Standard Proctor test, the weight of rammer is ________
a) 4.5 kg
b) 18 lb
c) 2.5kg
d) 20 lb

Explanation: In Standard Proctor test, the layers of the specimen are tested with a free fall of rammer of weight 2.5 kg or 5.5 lb. The test consists in compacting at various water contents.

12. In Standard Proctor test, the free fall height is ________ inches.
a) 5
b) 12
c) 16
d) 18

Explanation: In Standard Proctor test, the layers of the specimen are tested with a free fall of rammer of weight 2.5 kg or 5.5 lb with the height of free fall being 12 inches or 310 mm.

13. The void ratio is increased by compaction.
a) True
b) False

Explanation: Compaction is a process by which the soil particles are artificially rearranged and packed together in a closer state of contact by mechanical means. This arrangement reduces the porosity of the specimen and hence the voids ratio.

14. The compaction reduces _________
a) strength
b) stability
c) air voids
d) dry density

Explanation: When the soil is compacted, it reduces the voids ratio and also its porosity. Hence the sir voids are reduced by the compaction process. The compaction increases the strength, stability and the dry density of the specimen.

15. _______ is a process in which soil particles are artificially rearrange into a close state.
a) Tension
b) Compaction
c) Sway mechanism
d) Consolidation

Explanation: Compaction is a process by which the soil particles are artificially rearranged and packed together in a closer state of contact by mechanical means. While, consolidation is the natural process of reduction in the voids ratio of the specimen.

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