Use of digital image correlation to confirm the enhancement of concrete-epoxy resin mortar adhesion through surface precoating treatment

The method employed to bond concrete and epoxy mortar determines the strength of the interface in the resulting concrete composite structure. This paper presents a method for improving concrete-epoxy resin mortar adhesion through the precoating of concrete surfaces with resin. Resin concentrations of 10, 20, and 30 wt% were diluted in acetone. The failure process, interface strength, and crack propagation at the interface were investigated using a four-point bending test and digital image correlation technol-ogy. Increasing the amount of epoxy resin in the precoating solution improved the load-bearing capacity of the concrete-epoxy resin mortar interface by approximately 15% and changed the failure mode of the interface from near brittle to quasibrittle. Equivalent linear elastic fracture mechanics and double-K cri-teria analysis of the fracture toughness of the interface revealed that surface precoating considerably delayed initial cracking and improved surface toughness. Scanning electron microscopy of treated and nontreated specimens revealed that the toughness of the interface increased because the resin precoating on the concrete surface increased the area of contact between the epoxy resin mortar and concrete, which enhanced the interlocking effect and improved the strength of the interface. (c) 2021 Elsevier Ltd. All rights reserved.