Abstract:

Micromechanics theory was employed to investigate the effect of coarse aggregates and air voids on asphalt mixtures’ viscoelasticity. First, Mori-Tanaka’s equivalent inclusion method was used for coarse aggregates and air voids respectively to solve the hybrid inclusions problems of asphalt mixtures in Laplace space. Then the viscoelastic constitutive In order to reveal the effects of coarse aggregates and voids on the viscoelasticity of asphalt mixtures, the hybrid inclusion problem of asphalt mixtures in Laplace space is solved by using Mori-Tanaka＇s equivalent inclusion method. Then, based on the macroscopic mean field theory, the viscoelasticity of asphalt mixtures is discussed according to that of asphalt mortar matrix. Moreover, by taking the predictions under uniaxial and simple-shear stresses for example, the influences of coarse aggregates and voids on the performances of asphalt mixtures are investigated. The results show that the viscoelastic constitutive equation of asphalt mixtures can be expressed as the product of a comprehensive influence coefficient of coarse aggregates and voids and the viscoelastic constitutive equation of asphalt matrix, that the increase of air voids may result in the decrease of viscoelasticity, while the volumetric fraction of coarse aggregates has an opposite effect, that the weakening effect of air voids is slighter than the strengthening effect of coarse aggregates, that coarse aggregates and voids result in a comprehensive enhancing coefficient of stiffness for asphalt mortar, that the enhancing coefficient under simple-shear stress is approximately 2 times that under uniaxial stress, and that Poisson＇s ratio of asphalt mortar matrix can be regarded as a constant in the following researches due to its slight effect on the comprehensive influence coefficient.

Key words: asphalt mixture, viscoelasticity, micromechanics, coarse aggregate, void, comprehensive influencecoefficient