Explore the vast range of titles available.

Present paper deals with the development of a Mechanistic-Empirical model of the strain-based design of perpetual road pavement using Odemark's principle. The bituminous pavement which can withstand minimum design traffic of 300 msa has been classified as perpetual pavement in this paper. The pavement has been considered as a three-layered system with a top layer of bituminous mix followed by unbound granular materials which rest on soil subgrade. The constituent bituminous layer thickness in the pavement has been determined by limiting the radial tensile strain at the bottom of the bituminous layer against fatigue and the vertical compressive strain at the top of the subgrade against rutting. The allowable strain against rutting and fatigue has been used in the present analysis from mechanistic-empirical correlations recommended in IRC:37-2018. The pavement section has been transformed into a homogeneous system by Odemark's method for application of Boussinesq's theory. To validate the thickness of the perpetual pavement, the strain at different layer interfaces in the pavement was compared using IITPAVE software, which shows the pavement section using present method is safe against rutting but marginally fails under fatigue. Moreover, conventional pavement thickness obtained using IRC:37-2018 were compared with the present method, which shows reasonably good convergence. It has been found that the bituminous layer thickness in a layered system of pavement seems to be more sensitive to fatigue than rutting. In this backdrop, modified fatigue and rutting strain values have been recommended for the design of perpetual road pavement.

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.