Quantification of damage-related dissipation of asphalt concrete using the viscoelastic continuum damage framework

Fatigue behavior of asphalt concrete can be characterized using the dissipation that occurs due to damage of the material. However, it is difficult to obtain this dissipation from fatigue test results because of the existence of other modes of dissipation in the material, such as viscous friction. In this study, a method was developed to determine this damage-related dissipation using the framework of viscoelastic continuum damage models. After making an assumption for the general form of the work potential, including an assumption that it depends on a damage parameter, an expression was obtained for damage-related dissipation. The expression was then used to obtain another simpler expression for the fatigue dissipation in a cycle by considering some approximations in the evolution of the damage parameter. The final expression requires only the variation of the storage modulus with the number of cycles to determine the evolution of fatigue dissipation in the tests. The fatigue dissipation determined in this manner was used to identify fatigue failure of beams in four-point beam fatigue tests and to predict the fatigue life of asphalt concrete when the duration of a fatigue test is relatively long.