Constitutive modeling of fatigue damage response of asphalt concrete materials

The fatigue damage response of asphalt concrete is modeled with a proposed damage evolution function in the context of continuum damage healing mechanics. The uniaxial constant strain rate test is used to identify damage density experimentally during this test and to propose a form for the evolution of the damage density variable in the model. In addition, the model is formulated to include the microdamage healing effect. The proposed damage model is incorporated in the pavement analysis with a nonlinear damage approach model that includes Schapery’s viscoelastic model, Perzyna’s viscoplastic model, and the microdamage healing model, which is used to simulate the fatigue damage response of asphalt concrete. The damage model is validated against extensive experimental data, including constant strain rate, cyclic displacement-controlled tests, and cyclic stress-controlled tests over a range of temperatures, strain rates, loading frequencies, and stress–strain levels and amplitudes. Model predictions show that the proposed damage model is capable of predicting the fatigue damage response of asphalt concrete subjected to different loading conditions.