Test: Particle Size Classification - Civil Engineering (CE) MCQ

For general engineering purposes, soil can be classified in terms of
particle size, textural and unified soil.

Based on particle size, soil can be classified as
1) U.S. Bureau of soil and public road administration system
2) The M.I.T. classification system
3) Indian standard classification system
4) International soil classification system.

In the particle soil classification system, soils are arranged to the grain size.

Terms such as gravel, sand, silt, and clay are used to indicate grain sizes .these terms are used only as designation of particle size.

As the system is classified based on size, it is preferable to use the word ‘silt size’ and ‘clay size’ in place of simply ‘silt’ or ‘clay’.

Indian standard classification (IS: 1948-1970) is based on the M.I.T. system.

Soil occurring in nature is a complex mixture composed of the following components:

• Decomposed substance: Organic matter from decomposed plants and animals, providing nutrients.


• Sand: Coarse particles that improve drainage and aeration.


• Silt: Medium-sized particles that retain moisture and nutrients.


• Clay: Fine particles that hold water and nutrients well.
  Since soil includes all these components, the correct answer is option A: "All of the mentioned."
  Soil occurring in nature is composed of different percentage of sand, silt, and clay size particles.

 The purpose of soil classification is to arrange various types of soils in to groups according to their engineering or agricultural properties.

Since properties of clay soils is less dependent on particle size distrubution(textural classification) and more dependent on size it is best suited for clay soil.

Particle size classification used only as designation of particle sizes, and do not signify the naturally occurring types which are mixtures of particle of different sizes.