Mid-America Transportation Center


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Report # MATC-UNL: 427 Final Report 25-1121-0001-427


Copyright 2012 Mid-America Transportation Center


This study investigated the impact of the realistic constitutive material behavior of asphalt layer (both nonlinear inelastic and fracture) for the prediction of pavement performance. To this end, this study utilized a cohesive zone model to consider the fracture behavior of asphalt mixtures at an intermediate temperature condition. The semi-circular bend (SCB) fracture test was conducted to characterize the fracture properties of asphalt mixtures. 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 pavement subjected to heavy truck loads. Extensive creep-recovery tests were conducted at various stress levels and multiple service temperatures to obtain the stress- and temperaturedependent viscoelastic material properties of asphalt mixtures. Utilizing the derived viscoelastic and fracture properties and the UMAT code, a typical pavement structure was modeled that simulated the effect of material nonlinearity and damage due to repeated heavy truck loads. Twodimensional finite element simulations of the pavement structure demonstrated significant differences between the cases: linear viscoelastic and nonlinear viscoelastic modeling with and without fracture in the prediction of pavement performance. The differences between the cases were considered significant, and should be addressed during the process of performance-based pavement design. This research demonstrates the importance of accurate and more realistic characterizations of pavement materials.