Viscoelastic-plastic damage model for porous asphalt mixtures: Application to uniaxial compression and freeze-thaw damage

Porous asphalt mixture increasingly used in highway pavement applications is an open graded composite material which has fewer fines and more air voids compared with conventional dense graded asphalt mixtures. The freeze thaw resistance of the mixture is crucial for the performance of porous asphalt pavement especially when clogging is unavoidable. A simple viscoelastic-plastic damage model is developed to evaluate the effects of freeze-thaw of porous asphalt mixtures. Generalized Maxwell and Drucker-Prager model are used to determine the viscoelastic and plastic responses respectively. The damage and its evolution is characterized by Weibull distribution function. Experimental data from uniaxial compressive strength tests, conducted at different strain rates and temperatures, are used to calibrate the model. The sensitivity of model parameters to loading conditions is identified. Simulation results suggest that loss of cohesion is the dominant mechanism of failure in porous asphalt mixtures under freeze-thaw cycles. Freeze-thaw effects also lead to changes of plastic potential surface and induce large volumetric strains under loading.