Bonding Damage Evolution Process of Concrete–Epoxy Grout Composite Under Dry–Wet Interface Condition

The bonding strength of epoxy grout-concrete composite was investigated by axial tensile test to reveal the bonding damage evolution mechanism between epoxy grout and concrete under dry and wet interface condition. The ringing count, b value and the spatial position of acoustic emission (AE) source during the tensile process of composite were obtained by AE technique, and the spatial evolution process of bonding damage of composite was analyzed. The evolution characteristics of strain and displacement damage on the fracture surface of the composite under wet and dry interface condition were obtained by a digital image correlation method. The results show that the bonding strength under dry interface condition is 60% higher than that under wet interface condition. Under wet interface condition, the AE source of epoxy grout-concrete is concentrated at the interface, and a regular strain concentration zone is formed at the interface, showing the characteristics of interface failure. Under dry interface condition, however, there are a lot of AE sources in the concrete, and there are several irregular strain concentration zones on the fracture surface, indicating the failure mode of the concrete matrix as a whole.