Thin overlay analysis using finite element method

Thin Asphalt Concrete (AC) overlays are generally used as a preservation treatment for rigid and flexible pavements to improve riding quality, extend service life, and reduce noise levels on pavements. However, analyzing thin asphalt layers is complicated compared with the conventional methods of mechanistic analysis because these layers are directly exposed to vehicular loading and environmental stimulations. The gradients of material properties resulting from aging and moisture damage, in addition to mix heterogeneity and complex microstructure, violate some of the basic assumptions of pavement evaluation used to date. The proposed research work aims to estimate the performance of thin AC overlays using a mechanistic approach addressing the existing complexities. Three-dimensional finite element simulations is developed, taking into account features such as vehicular loading, different layer thicknesses of the thin AC overlay layer and variations in material parameters. Changes in the behavior of critical response parameters in the pavement structure and the tire trajectory give an idea about the characteristic features of the mixes used and the properties of layers when subjected to external loads. It was concluded from this analysis that the behavior of a pavement structure with thin asphalt overlays is affected to a greater extent due to a variation in the thickness of overlay layer. In comparison, the impact of change in the linear viscoelastic characteristics of the mix types used was not very significant. Compressive and shear forces were found dominant in governing the performance of pavements.