AbstractThe EAC+SMA composite structure, made from epoxy asphalt concrete (EAC) with stone matrix asphalt (SMA) concrete on top, is a double-layered heterogeneous structure applied to steel bridge deck pavement (SBDP) in recent years. The interlayer bonding performance is key to the long-life application of EAC+SMA. In this study, the objective is to investigate the interlayer bonding performance of EAC+SMA composite structure to identify its best design and construction strategy. To achieve this goal, a series of pull-off tests and interlayer shear tests under different test conditions were performed on four commonly used EAC+SMA composite structures. The effects of design parameters, the construction conditions, and the application environment of EAC+SMA structure on its interlayer bonding performance were evaluated. The results showed that the EAC+SMA composite structure with SMA13 (SMA mixture with the nominal maximum aggregate size of 13.2 mm) as the wearing layer material and epoxy resin–based bonding material possessed the best interlayer bonding performance among the four composite structures. It is suggested that the bonding layer and SMA layer should be constructed after the Marshall stability of the EAC layer reaches 15 kN, and the construction interface should be clean to achieve the best interlayer bonding performance for the EAC+SMA composite structure. In addition, the mixed-mode cohesive zone model was developed to characterize the interlayer bonding behaviors in the mechanical analysis of EAC+SMA composite structures, and the proposed numerical characterization method could be used to obtain more accurate mechanical results for the structure design compared with the traditional numerical characterization method under the interlayer continuous assumption.