# Soil Mechanics Questions and Answers – Slaking of Clay and Bulking of Sand

This set of Soil Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Slaking of Clay and Bulking of Sand”.

1. Decrease in water content causes _______
a) shrinkage
b) swelling
c) frost heave
d) frost boil

Explanation: Decrease in water content of soil results in decrease in the volume of the soil thus causing the shrinkage of the soil.

2. Increase in water content causes _______
a) shrinkage
b) swelling
c) frost heave
d) frost boil

Explanation: Increase in water content of soil results in increase in the volume of the soil thus causing the swelling of the soil.

3. Arrange the following to explain the shrinkage of the soils.
I. Compression in soil
II. Formation of meniscus
III. Reduction in volume
a) (II), (I), (III)
b) (I), (II), (III)
c) (III), (I), (II)
d) (III), (II), (I)

Explanation: When saturated soil is dried, a meniscus develops in the voids at the solid surface. Formation of meniscus leads to tension in the soil water that leads to the compression of the soil structure and consequent reduction in the volume.

4. When the meniscus attains a minimum value, shrinkage is ________
a) maximum
b) minimum
c) no effect
d) zero

Explanation: When the meniscus attains a minimum value, compressive forces which are developed are maximum causing the shrinkage to also be maximum.

5. The degree of shrinkage does not depend upon _________
a) initial water content
b) type of clay
c) cation exchange capacity
d) amount of clay

Explanation: Cation exchange capacity is factor influencing the swelling of soil. The degree of shrinkage depends upon type and amount of clay minerals, mode and environment of deposition.

6. Arrange the following to explain the swelling of the soils.
I. Increase in tension in the pore water
II. Reduction in compressive stress in the soil
III. Menisci are destroyed
a) (II), (I), (III)
b) (I), (II), (III)
c) (III), (I), (II)
d) (III), (II), (I)

Explanation: When water is added to a soil menisci are destroyed resulting in tension in the pore water and the consequent reduction in the compressive stress in the soil.

7. Free swell ceases when the water content reaches ________
a) liquid limit
b) plastic limit
c) shrinkage limit
d) plasticity index

Explanation: Free swell of a soil is the increase in the volume of soil without any constrains on submergence in water and it ceases when the water content reaches the plastic limit.

8. The slaking of the clay occurs when clayey soil is dried ________
a) below the shrinkage limit
b) above the shrinkage limit
c) below the plastic limit
d) above the plastic limit

Explanation: When the clayey soil is dried below its shrinkage limit, it will attain its minimum volume. When this is suddenly immersed in water it causes slaking.

9. Slaking is due to the ______ into the drying of the soil below the shrinkage limit.
a) entry of water
b) exit of water
c) entry of air
d) exit of air

Explanation: When the water enters the voids (containing air during drying process), due to immersion, menisci is formed, causing high pressures and subsequent explosion of the voids leading to the disintegration soil structure.

10. The bulking of sand is maximum when the water content is _________
a) 0
b) 5 to 6%
c) 15 to 17%
d) 20 to 21%

Explanation: The bulking of sand is maximum when the water content is 5 to 6%. Saturating the soil above 5 or 6% will result in destruction of the menisci and decrease in the volume.

Sanfoundry Global Education & Learning Series – Soil Mechanics.

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