Two-step approach to prediction of asphalt concrete modulus from two-phase micromechanical models

A two-step approach is proposed to predict the modulus of asphalt concrete from existing micromechanical models. The asphalt concrete microstructure is represented by a two-phase model, which consists of a large spherical aggregate particle surrounded by a spherical shell of fine aggregate-filler-binder mixture as the matrix. The fine aggregate-filler-binder mixture is further represented by a two-phase model, which treats fine aggregate as a spherical inclusion and the mixture of filler and binder as the matrix. The modulus of asphalt concrete is predicted from the volumetric fractions, Poisson's ratios, and moduli of the aggregate and filler-binder mixture by applying the appropriate two-phase models in two steps. An asphalt concrete and two mixtures that replicate the fine aggregate-filler-binder submixture and the filler-binder submixture in the asphalt concrete have been tested for modulus. The tests results show that the predicted results from the appropriate models reasonably approximate the measured results.