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MIT System of Classification of Soil| Indian Standard Soil Classification System (ISSCS)

MIT System of Classification: The MIT system of classification of soil was developed by Prof. G. Gilboy at the Massachusetts Institute of Technology in the USA. In this system, the soil is divided into four groups:

1.Gravel    Particle size greater than 2 mm.
2.Sand     Particle size between 0.06 mm to 2 mm.
3.SiltParticle size between 0.002 mm to 0.06 mm.
4.SiltParticle size smaller than 0.002 mm.  
  • Sand is divided into three groups: Fine, Medium, and Coarse
  • Silt is also divided into three groups: Fine, Medium and Coarse

Interesting for You: Textural Classification of Soil: Soil Texture Triangle

Below is the chart see the detail of MIT system

MIT system of soil classification
Fig.1. MIT system of soil classification

The full form of symbols are: F = Fine, M = Medium, C = Coarse

Indian Standard Soil Classification System (ISSCS)

Indian standard soil classification system (ISSCS) adopted by the Bureau of Indian Standards is in many respects similar to the unified soil classification system (USCS). However, there is one basic difference in the classification of fine-grained soils. The fine-grained soils in ISSCS are sub-divided into three categories of low, medium, and high compressibility instead of two categories of low and high compressibility in USCS. ISSCS classifies the soils into 18 groups as per the tables presented below.

 1) Coarse-grained soils

Coarse-grained soils are subdivided into gravel and sand. The soil is termed gravel (G) when more than 50% of the coarse fraction (plus 75µ) is retained on a 4.75 mm LS, sieve, and termed sand (S) if more than 50% of the coarse fraction is smaller than 4.75 mm LS. steve. Coarse-grained soils are further subdivided into 8 groups.

2) Fine-grained soils

The fine-grained soils are further divided into three sub-divisions, depending upon the values of the H liquid limit.

  1. Silts and clays of low compressibility

These soils have a liquid limit of less than 35 (represented by symbol L).

Plasticity Chart(Indian Standard soil Classification System)
Fig.2. Plasticity Chart(Indian Standard soil Classification System)
  • Silts and clays of medium compressibility

These soils have a liquid limit greater than 50 (represented by symbol H). Fine-grained soils are further sub-divided into 9 groups.

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