Micromechanical Analysis on Viscoelasticity of Asphalt Mixtures

Abstract

Mori-Tanaka equivalent inclusion micromechanics theory was employed to investigate the viscoelasticity of asphalt mixture. Asphalt mixture was regarded as composites which treated coarse aggregate as a rigid inclusion and the mixture of fine aggregate, filler and binder as viscoelastic matrix. The constitutive relations of coarse aggregate inclusion and fine aggregate-filler-binder matrix were converted into elastic problems by Laplace transformation. Then the Mori-Tanaka equivalent inclusion and average theory were used to deduce the viscoelastic performance of asphalt mixture based on that of asphalt mortar in Laplace space. The result shows that (1) coarse aggregate inclusion can enhance the viscoelastic performance of fine aggregate-filler-binder matrix and viscoelastic constitutive relation of asphalt mixtures can be expressed as the product of an enhancement coefficient of coarse aggregate and the viscoelastic constitutive relation of fine aggregate-filler-binder matrix; (2) the viscoelasticity of the complex asphalt mixture can be predicted from the viscoelasticity of the homogeneous fine aggregate-filler-binder matrix by using the enhancement coefficient; (3) the enhancement coefficient is higher than 1.0 and it rises with increasing of coarse aggregates’ volumetric fraction or Poisson’s ratio of fine aggregate-filler-binder matrix but the effect of the former is more important than that of the latter.