Evaluation of Permanent Deformation in Asphalt Overlays Using Default Finite Element Tools in ABAQUS

The satisfactory performance of an asphalt overlay is influenced by various factors including the existing pavement condition, traffic loading, and environmental conditions such as moisture and temperature, among others. The objective of the work documented in this paper was to numerically evaluate the permanent deformation (PD) characteristics of typical asphalt overlays in hot tropical climates, like Zambia, using the default creep and elasto-visco-plastic models in the 2-D finite element (FE) tools of the ABAQUS software. These models are converted into a numerical formulation for implementation in FE analysis using user-defined material subroutines (UMAT). Supplemented with dynamic modulus and repeated load laboratory tests, input material properties, such as the layer modulus, were generated based on falling weight deflectometer (FWD) back-calculated data using iterative techniques and regression analysis to accurately account for local temperature normalization. The corresponding results showed that the application of local calibration factors on FWD deflection measurements before back-calculation computations provide reliable material characteristics input parameters for the FE analysis. Furthermore, the FE analytical PD predictions were also consistent and correlated well with the rutting results measured on laboratory scaled representative pavement structures under accelerated trafficking using the third-scale mobile load simulator (MLS3).