ANALYSIS OF SEMI-RIGID PAVEMENTS

Abstract

Pavements are generally classified in two categories. Flexible and Rigid. Flexible pavements consists of a series of layers with the highest quality material at or near the surface(1). The load carrying .. p capacity of ,Flexible pavements is brought . by the load diet-ributicn characteristics of the layered system. The materials used in the layers are considered to have negligible flexural strength. The óuzzcu flexible pavement layers are. crashed . stone or gravel, Water Baird Macadam ("WBM), Bituminous mixes a c. Rigid pavements are those .bavibg . ccns derable _ flexural strength and high modulus of elasticity, capable of distributing load over a. relatively wide area. The major portion of structural capacity of the Rigid pavements is supplied by the slab itself. Portland cement ecmcrete is the onlymaterial considered in the category of - Rigid Pavements. Hence at present there are two methods of pavement design _ Rigid pavement design when ..considering materials which have considerable flexural strength . (.like that of cement concrete) . and flexible pavement design when considering materials which have negligible flexural strength B). Though pavement materials like .soil-cement, soil.lime.flyash, Pozzuolanic concrete, and lean cement 2. caacrete have web low flexural strength than cesient concrete, still they possess noteworthy flexaral strength„ The 28 days flexural strength of cement concrete used in pavement ccnstructica is in the range of 120 to 180 Kg/m& whereas that of soil-cement usually used as base-c rse ccnst ii ct c.n . is In the range of 7 to 50 Kg/ &. Hence there is a need for an ante mediate classification and a suitable method of design for such pavements. This category of pavement material may be classified as .semi-rigid or semi-flexible materi