FACTORS IN FLEXIBLE PAVEMENT DESIGN

Abstract

Pavements can be broadly classified as "rigid" and "flexible". The conspicuous difference between rigid and flexible pavement is the presence of flexural strength in the top wearing course in the case of former and near absence in the latter type of pavement. It is this difference which provides a demarkation in the identification not only of the two types of pavements but even mode of and approach to the design. The rigid pavement, generally, has a concrete wearing course and are prohibitively costly. The flexible pavements are comparatively cheaper. The general notion exists that the thickness required in the case of rigid pavements is lesser than the one in case of flexi-ble ones. This is not always the case. In fact, under certain conditions, the rigid_pavement needed would be thicker than the flexible one. It has been shown (1) that when the subgrade has a 04R (a subgrade strength factor) value of less than 200 the thickness of flexible pavement required is less than the thick-ness of rigid pavement. On the other hand, if the subgrade is very soft, the thickness of flatible7pavatent is many times higher than the thickness of rigid pavement. It has also been shown the load bearing capacity of a