Development and validation of nonlinear viscoelastic damage (NLVED) model for three-stage permanent deformation of asphalt concrete

Modified Burgers model was applied to develop residual viscoelastic (RVE) and nonlinear viscous (NLV) strains for asphalt concrete subjected to repeated loading, and nonlinear viscoelastic damage (NLVED) model was then established and validated by incorporating damage variable. It is found that RVE strain proportion decreases with loading cycles and rest period, and NLV strain is predominant in total permanent strain. The repeated load permanent deformation (RLPD) test results show that the proposed NLVED model can well describe the three stage behavior of asphalt concrete in terms of permanent strain, strain rate and flow number. The damage evaluation shows that the damage of asphalt concrete is generated in the initial load and monotonically increases with the increasing loading cycles and becomes bigger and develops rapider at higher stress and temperature conditions.