Fatigue damage growth and healing of asphalt concrete are studied in this paper using laboratory and field experiments. The field study was performed using the stress wave technique on asphalt pavement sections with varying degrees of damage. The elastic modulus of an asphalt concrete layer is calculated from the stress wave data using the dispersion analysis based on Short Kernel Method. The laboratory study employs two fundamentally different approaches to modeling the mixture fatigue behavior; continuum approach and micromechanical approach.

The continuum approach applies the elastic-viscoelastic correspondence principle to eliminate the time-dependence from the hysteretic behavior of asphalt concrete under cyclic loading. Pseudo stiffness, stiffness after the application of the elastic-viscoelastic correspondence principle, decreases following a characteristic S-shape curve due to the fatigue damage growth when plotted against number of loading cycles. This curve is vertically shifted when rest periods are introduced, resulting in a longer fatigue life. The same trend is observed from the field study between the elastic modulus and the number of loading cycles.

Work potential theory, a continuum damage theory based on thermodynamics of irreversible process, is then applied to the laboratory data to model the changes in pseudo stiffness due to fatigue damage growth and microdamage healing. The resulting model is found to be mode-of-loading independent and capable of predicting the changes in stress-strain behavior under compound loading histories with multi-level loading and varying durations of rest. A validation study is performed on the fatigue performance prediction model using the data obtained from uniaxial fatigue testing of AAD and AAM mixtures under constant stress/strain amplitude cyclic loading histories with and without rest periods.

Finally, a micromechanical approach is presented which describes a fracture process as a balance between the energy imparted to the system and the energy taken up by the newly created crack surfaces. Different microdamage healing behavior of AAD and AAM mixtures described by the coefficients in the continuum damage model is explained by the difference in micromechanical properties between the two binders, such as total cohesive surface energy and different proportions of the Lifschitz-Van der Waals and the acid-base components in the surface energy.