On the behavior of a parallel elasto-visco-plastic model for asphaltic materials

The paper considers a dissipation energy based elasto-visco-plastic constitutive model formulated by coupling in parallel visco-elastic and elasto-plastic components, which has been developed at Delft University of Technology for the response prediction of asphaltic materials. To discuss the various aspects of the model under different creep loads, a simplified one-dimensional analytical solution is derived. Three different analytical cases are treated: visco-elastic response, elasto-visco-plastic response in which plasticity develops during the loading and instantaneous plasticity. The analyses show that the interaction between the parallel visco-elastic and elasto-plastic components of the model are an important aspect of the predictive capabilities of the model. A case is derived in which short duration loading of the model could lead to a prediction of increasing strains during the unloading phase. Care should be taken when choosing the material parameters of the model to avoid this erroneous prediction.