Characterization of asphalt concrete in tension using a viscoelastoplastic model.

摘要

The objective of the research presented herein is to develop an accurate and advanced material characterization procedure to be incorporated in the Superpave performance models system. The procedure includes the theoretical models and its supporting experimental testing protocols necessary for predicting responses of asphalt mixtures subjected to tension loading. The model encompasses the elastic, viscoelastic, plastic and viscoplastic components of asphalt concrete behavior. Addressed are the major factors affecting asphalt concrete response such as: rate of loading, temperature, stress state in addition to damage and healing. Modeling strategy is based on modeling strain components separately and then adding the resulting models to attain a final integrated ViscoElastoPlastic model. Viscoelastic response, including elastic component, is modeled based on Schapery's continuum damage theory comprising of an elastic-viscoelastic correspondence principle and work potential theory. As for the viscoplastic response, which includes the plastic component, its characterization stems from Uzan's strain hardening model. The testing program required for developing the models consists of complex modulus testing for determination of material response functions, constant crosshead rate testing at low temperatures for viscoelastic modeling, and repetitive creep and recovery testing for viscoplastic modeling. The developed model is successful in predicting responses up to localization when microcracks start to develop. After that, fracture process zone strains detected using Digital Image Correlation are used to extend the model's ability in predicting responses in the post-localization stage. However, once major macrocracks develop, the currently developed model ceases to accurately predict responses. At that state, the theory of fracture mechanics needs to be integrated with the current continuum damage-based model.