As group index is a mean of rating the value of soil as a sub-grade material. It can be used for finding the performance and quality of the soil.

Triangular classification of U.S. public road administration is a commonly used system for textural classification.

Since the textural classification is based on the percentages of sand, silt, and clay size making up the soil. Such a classification is more suitable for describing coarse-grained soil.

Soil classification of composite soils exclusively based on the particle size distribution is known as textural classification.

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

HRB classification system, also known as public road administration (PRA) is based on both the particle-size composition and plasticity characteristics.

A triangle, having equal length of sides (i.e. Equilateral triangle) is used in textural classification chart.

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

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

Soil occurring in nature is composed of a different percentage of sand, silt, and clay size particles.