Effect of Varying Subgrade Strength on Cost of a Rigid Pavement

It is generally believed that increase in subgrade strength leads to decrease in the thickness of a rigid pavement which helps in reducing the cost of pavement. The guidelines of Indian Roads Congress (IRC) for the design of rigid pavements also recommend the use of select soil of minimum CBR 8% in the subgrade for design of cement concrete pavement for roads having traffic greater than 450 CVPD. An attempt has been made in this paper to study the effect of variation in subgrade strength on thickness and cost of a rigid pavement. It is found that the thickness and cost of pavement may not decrease with an increase in the strength of subgrade soil. The provision of using select soil of minimum CBR 8% in the subgrade of the road as recommended by IRC, therefore, needs to be applied carefully.