Fatigue endurance limit of epoxy asphalt concrete pavement on the deck of long-span steel bridge

Fatigue crack damage in the epoxy asphalt concrete pavement of long-span steel bridge deck is still one of the most severe problems even though the fatigue endurance performance has been studied for a long time. In this study, it aimed at exploring the mechanism why the fatigue damage of the epoxy asphalt concrete occurred, as well as finding out the reason why fatigue test results in laboratory were different from those in practical engineering application. A finite element mechanics method was first applied to analyze the maximum strain value of the epoxy asphalt concrete pavement at different load positions, then fatigue performance of the epoxy asphalt concrete was investigated using a four-point bending fatigue testing method, and finally a three-parameter fatigue equation model, which was demonstrated to be feasible and rational, was utilized to determine fatigue endurance limit for the first time. The fatigue damage of the epoxy asphalt concrete occurred in a short time once the strain level with driving load was larger than fatigue endurance limit. In contrast, the fatigue damage did not appear in a long time if the strain level was less than the fatigue endurance limit. It is suggested that the fatigue endurance limit be adopted as a control parameter in the design phase of epoxy asphalt concrete pavement. These findings advance previous design specifications in the world, and could help extending service life of epoxy asphalt concrete pavement of long-span steel bridge deck.