A viscoplastic constitutive model for hot mix asphalt in compression at high confining pressure

In this study, the experimentally observed rate-dependent viscoplastic hardening–softening of hot mix asphalt (HMA) is modeled using Perzyna’s flow rule and a rate-dependent yield stress function. The yield stress function, which is adopted from the convolution integral in linear viscoelasticity, is applied with a strain hardening rule in order to address both the sudden and gradual changes in rate dependence of the viscoplastic media that are due to repetitive creep and recovery loading. The experimental study is performed to characterize the behavior of HMA and verify the developed model at 55 °C with 500 kPa confining pressure. The developed model shows good agreement with the measured viscoplastic responses of HMA under various load levels and pulse times of repetitive creep and recovery loading histories.

Research highlights
► HMA show softening behavior during unloading condition.
► Not only accumulative loading time, but also rest period has very important effect on viscoplastic strain development in HMA at high confining pressure.
► A viscoplastic model developed by author predicts well the behavior of HMA at high confining pressure.