Jordan Journal of Civil Engineering

Mechanistic-Empirical Design of Overlay Based on Vertical Interface Stress and Curvature Index of Deflection Basin


Manoj Kumar Sahis; Partha Pratim Biswas; Geetam Saha;


The objective of putting an overlay on the existing damaged pavement is to limit stress, strain and deflection at different layer interfaces of the multi-layered system in a pavement. However, the objective of the present study is to determine the bituminous overlay thickness on the top of the in-service flexible road pavement by limiting the vertical interface stress at pavement -overlay interface. In the present paper, a new overlay with old pavement has been considered as a two-layered system. The vertical stress at pavement - overlay interface due to wheel load on the surface has been determined using Boussinesq's theory after the required transformation of the two-layered system by Odemark's method. The vertical stress thus obtained has been made equal to the allowable vertical stress found from Danish and Huang's empirical findings to estimate the overlay thickness for different axle loads and pavement deflections. The overlay thickness obtained using the present methods and the Asphalt Institute method have been compared in this paper. The convergence of results between two stress-based overlay design methods was found reasonable. Base layer index as a measure of the curvature of overlay under wheel load has been considered as a performance criterion. Comparative analysis of the index obtained for different overlay thicknesses from stress-based and deflection-based criteria has been presented in this paper. It was found from the base layer index that the overlay thickness estimated using the stress-based methods was reliable and safe against cracking. Sensitivity analysis shows that the modulus of the bituminous mix is more sensitive in comparison to axle load repetitions for estimation of overlay thickness.


Base layer index, Interface deflection, Odemark’s method, Overlay, Vertical interface stress, Sensitivity.