Experimental researches on visco-elastoplastic constitutive model of asphalt mastic

The nonlinear visco-elastoplastic behavior of asphalt mastic is studied. A series of uniaxial compression creep tests are conducted under different temperatures of 20, 40, 45, 50 and 60 °C and stress levels of 0.1, 0.15, 0.2, 0.25 and 0.3 MPa. A visco-elastoplastic model that can completely characterize three-stage creep deformation behavior of asphalt mastic is proposed by adding an additional viscoplastic string to the Burgers model. The creep constitutive equation of the model is established for uniaxial loading conditions. The effects of loading stress and temperature on the creep behavior are investigated, and the model parameters in the creep constitutive equation are expressed as functions of stress and temperature. The predictions from the proposed model and the power model are compared with the experimental results. It is shown that the presented model has better agreement with the experiments.