Development of a Mechanistic-Empirical Design Approach for Determination of Cement Concrete Overlay Thickness Considering Bonded and Unbonded Interface Condition

Abstract

The service life of an existing pavement decreases due to load or environment induced damage. In this context, present study aims to propose a mechanistic-empirical method for estimation of a concrete overlay thickness on top of an in-service bituminous pavement to increase its service life. The strength of the existing bituminous pavement in terms of effective modulus of subgrade reaction has been used as an input parameter in present study which has been back calculated using ASTM chart for different pavement layer thickness and elastic modulus of subgrade soil. In present paper, wheel load and temperature stress has been compensated with flexural strength of concrete for estimation of overlay thickness. Different interface bond condition between old bituminous pavement and new concrete overlay has been considered in present analysis. The result obtained shows that the unbonded concrete overlay thickness of is relatively higher than bonded overlay. Moreover, the overlay thickness increases with panel size in both bonded and unbonded condition. The thickness of concrete overlay has been validated with IITPAVE software as well as by National Concrete Pavement Technology Center (NCPTC) and American Concrete Institute (ACI) guideline which shows relatively good convergence and prove the reliability of the present method as an alternative approach of concrete overlay design.

Keywords: wheel load, temperature stress, Flexural Strength, bonded, unbonded, panel size