Development of a thermo-viscoplastic constitutive model for HMA mixtures

Hot mix asphalt (HMA) mixtures exhibit temperature and rate dependencies under monotonic and cyclic loads. Most current constitutive models used in design and prediction of the performance of asphalt pavements do not incorporate these characteristics into the equations. These limitations cause serious problems in practical applications. This paper presents the development of a thermo-visco-plastic constitutive model that incorporates the temperature and loading rate into the Hierarchical Single Surface (HiSS) plasticity based model. This model was able to reflect the non-linear plasticity, as well as the temperature and loading rate dependencies of the asphalt mixtures. A series of triaxial and creep tests at three temperatures were performed to calibrate the material properties. A back-predicting algorithm for the HiSS thermo-visco-plastic model was developed during this study. A comparison of numerical analysis obtained from the proposed model and experimental results was conducted based on this algorithm. A good agreement was observed from the back-calculation and the experimental results. Further studies of the applicability of this model in predicting pavement performance are recommended.