Monday, 12 February 2018

Highway Research Board(HRB)Classification(of soil)

This system of classification is based on both the particle size distribution as well as the plasticity characteristics of soil.This system is mostly used for pavement construction. In this system soils are divided in to 7 primary group , designated as A-1,A-2…..A-7.
Group A-1 is divided into two sub-group and group A-2 is divided into four sub-groups.
A characteristic group index is used to describe the performance of soils when used for pavement construction .higher value of group index indicates poorer of the material.