Uniaxial fatigue testing of diverse asphalt concrete mixtures

The uniaxial fatigue test is a useful method for developing constitutive models to describe the fatigue behaviour of asphalt concrete mixture owing to the uniform states of stress across the specimen section. As part of the NCHRP 944- A project, a proposed uniaxial fatigue test protocol and software were developed to assess fatigue damage and healing. In this study, the protocol was used to evaluate a wide range of conventional and modified asphalt mixtures sampled from national and international projects as well as laboratory prepared mixtures with different volumetric properties. The study mixtures included those modified with rubber, polymer, fiber, warm mix additives, and combined rubber and warm mix. The fatigue analysis was performed using the simplified viscoelastic continuum damage (S-VECD) approach where the damage characteristic (C-S) curves were established for each mixture, and then used to obtain the fatigue relationships through simulated predictions. Overall, the proposed uniaxial fatigue test protocol was successfully used with respect to the S-VECD formulation to capture fatigue behaviour of all tested mixtures.