# Soil Mechanics Questions and Answers – Flocculent and Dispersed Structures

This set of Soil Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Flocculent and Dispersed Structures”.

1. The single grained structure is characteristic of fine-grained soils.
a) True
b) False

Explanation: The single grained structure is characteristic of coarse-grained soils. The honeycomb, flocculent and dispersed structures are found in fine-grained soils.

2. The behaviour of coarse-grained soils is not governed by ________
a) gravitational forces
b) mass energy
c) colloidal forces
d) interaction with pore fluid

Explanation: The particles of coarse-grained soils are sometimes called as bulky particles and these do not possess plasticity and cohesion. Their behaviour is primarily governed by gravitational forces and mass energy rather than colloidal forces.

3. The dispersed occurs in_______
a) sand
b) remoulded clay
c) gravel
d) silts

Explanation: Coarse-grained soils like gravel and sand form single grained structure. Fine sand and silts occur in honeycomb structure.

4. ________ structure is highly compressible and less permeable.
a) Flocculent
b) Dispersed
c) Honeycomb
d) Singe grained

Explanation: The dispersed structure has face-to-face contact in an approximately parallel manner having a lesser void ratio. Thus they have highly compressibility and less permeability. Whereas, the flocculent structures have low compressibility and high permeability.

5. Coarse grained skeleton is a structure of soil which is present in _________
a) fine grained
b) composite soil with large amount of coarse grained particles
c) composite soil with large amount of fine grained particle
d) coursed grained

Explanation: Coarse grained skeleton is a composite structure. Composite soil with a large amount of coarse grained particles form ‘coarse grained skeleton’. While composite soil with a large amount of fine grained particle form ‘clay matrix’.

6. Flocculated structure contains charged particles.
a) True
b) False

Explanation: The flocculated structure is present in clay particles with larger surface area. These are charged particles with positive charge on edges and negative charge on face.

7. Clay present in the marine area has ________
a) Flocculent structure
b) Dispersed structure
c) Honeycomb structure
d) Singe grained structure

Explanation: The salt present in the marine water acts as an electrolyte and thus reduces the repulsive forces between the particles which leads to the formation of the flocculated structure. The have high shear strength.

8. Flocculated structure is formed when there is a _______
a) net repulsive force
b) net attractive force
c) cohesive force

Explanation: The flocculated structure contains charged particles and these are formed when there is net attractive force between adjacent soil particles. The dispersed structure is formed when there is a net repulsive force.

9. ________ is decomposed volcanic ash containing a high percentage of clay mineral.
a) Moorum
b) Peat
c) Dune sand
d) Bentonite

Explanation: Moorum is gravel mixed with red clay. Peat is a highly organic soil which is highlt compressible and fibrous. Dune sand is non-plastic uniformly graded fine sand.

Sanfoundry Global Education & Learning Series – Soil Mechanics.

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