Characterization of asphalt mix response under repeated loading using anisotropic nonlinear viscoelastic-viscoplastic model

Asphalt mixes exhibit a viscoelastic-viscoplastic behavior, and the contribution of the different constitutive components depends on the temperature and rate of loading. This paper presents an anisotropic nonlinear viscoelastic-viscoplastic model for asphalt mixes. The influence of the anisotropic aggregate distribution is accounted for in both the viscoelastic and viscoplastic responses. The model's parameters were determined based on the analysis of repeated creep triaxial tests on three asphalt mixes that included aggregates with different characteristics. The paper discusses the experimental factors that need to be considered in conducting the repeated creep tests in order to determine the model's viscoelastic and viscoplastic parameters. It also discusses the relationship between these parameters and mix properties. The results show that the mix nonlinear viscoelastic response, hardening, dilation or contraction behavior, and damage depend on aggregate properties.