Viscoelastic continuum damage model of asphalt concrete with healing

A viscoelastic constitutive model of asphalt mixtures that accounts for the rate-dependent damage growth and microdamage healing is presented in this paper. An elastic continuum damage model, which is based on thermodynamics of irreversible processes with internal state variables, is first reviewed and extended to a corresponding viscoelastic model using an elastic-viscoelastic correspondence principle. A rate-type internal state evolution law is employed to describe the damage growth and microdamage healing in asphalt concrete. An analytical representation of the model is established for the uniaxial loading condition. Tensile uniaxial cyclic tests were performed under the controlled-strain mode with different strain amplitudes to determine model parameters. The resulting constitutive model successfully predicts the damage growth and recovery in asphalt concrete under multilevels of loading, varying rates of loading, different modes of loading (controlled-strain and controlled-stress), and random rest periods.