Fatigue behavior of epoxy asphalt concrete and its moisture susceptibility from flexural stiffness and phase angle

Epoxy asphalt concrete (EAC) has been widely used in large span steel box girder bridges recently. The fatigue performance of EAC is critical in the pavement design on steel box girder. The four-point beam fatigue test was employed to evaluate the fatigue performance of EAC. The moisture susceptibility was evaluated by comparing the fatigue behaviors of the dry and moisture conditioned samples. The fatigue life was determined through four criteria: the yield point from Weibull plot, the half modulus ratio (SR) point, the peak phase angle point, and the sample failure. The results showed that the fatigue lives of EAC can be higher than conventional asphalt concrete by one or two orders in magnitude, indicating an excellent fatigue performance. Both the strain level and testing temperature have a significant influence on the fatigue behavior of the EAC, similar to conventional asphalt concrete. While phase angle has been rarely reported in previous studies, the finding indicated the peak phase angle point has a good potential to be used as a criterion of determining fatigue life of EAC after compared with other parameters. Moisture damage has a great influence on the fatigue performance of EAC according to the noticeable fatigue life reduction.