Numerical implementation and validation of a nonlinear viscoelastic and viscoplastic model for asphalt mixes

This study presents the numerical implementation and validation of a constitutive model for describing the nonlinear behaviour of asphalt mixes. This model incorporates nonlinear viscoelasticity and viscoplasticity to predict the recoverable and irrecoverable responses, respectively. The model is represented in a numerical formulation and implemented in a finite element code using a recursive-iterative algorithm for nonlinear viscoelasticity and the radial return algorithm for viscoplasticity. Then the model is used to analyse the behaviour of asphalt mixtures subjected to single creep-recovery tests at different stress levels and temperatures. This experimental analysis includes the separation of the viscoelastic and viscoplastic strain components and identification of the material parameters associated with these components. Finally, the model is applied and verified against a set of creep-recovery tests at different stress levels and temperatures.