Rutting and cracking modeling of asphalt pavements considering nonlinear viscoelasticity and cohesive zone fracture

This study investigates the mechanical impact of the constitutive material behavior of asphalt layer (both nonlinear viscoelastic and fracture) for the prediction of pavement performance. In this study, a cohesive zone model was utilized to consider the fracture behavior of an asphalt mixture. The Semi-Circular Bend (SCB) fracture test was conducted to characterize the fracture properties of the asphalt mixture. Fracture properties were then used to simulate mechanical responses of pavement structures. In addition, Schapery's nonlinear viscoelastic constitutive model was implemented into the commercial finite element software ABAQUS via a user defined subroutine (user material, or UMAT) to analyze asphalt pavements subjected to heavy truck loads. A series of creep-recovery tests were conducted at various stress levels to obtain the stress-dependent viscoelastic material properties of the asphalt mixture. Utilizing the derived viscoelastic and fracture properties and the UMAT code, a typical pavement structure was modeled to investigate the effect of nonlinear viscoelasticity and fracture damage due to repeated heavy truck loads. Mechanical responses from two-dimensional finite element simulations of the pavement structure are presented and discussed.