The essential difference between rigid flexible pavements is the manner in which they distribute the load over the sub-grade.

The purpose of wearing course, made of bituminous materials is to provide a smooth riding surface that is re silent and to resist the pressure exerted by the tyres.

Pavements are classified in to Flexible, rigid and semi-flexible, based on distributing loads.

Base course and sub-base course are used under flexible pavements primarily to increase the load supporting capacity of the pavement by distributing the load through a finite thickness of pavement.

The sub-grade is the foundation layer, the structure which must eventually support all the loads which come on to the pavement.

Depending upon the mode of supporting and distributing loads, pavements are classified in to Flexible, rigid and semi-flexible.

The design of flexible pavement is based on the principal that a surface load is dissipated by carrying it deep in to the ground through the layer of sub-grade.

Stability of the sub-grade is influenced by soil texture, water content, density, frost action, shrinkage and swelling and other climatic factors.

A flexible pavement consists of relatively then wearing surface and hence, can resist only very small tensile strength then the other pavement.

Rigid pavements are made up of Portland cement concrete and may or may not have a base course between the pavement and the sub-grade.