EXPERIMENTAL STUDY ON REPAIRING DIAGONAL CRACKS IN CONCRETE WITH MODIFIED EPOXY RESIN INFUSION

This study investigates the repair effectiveness of self-made modified epoxy resin potting adhesive on diagonal cracks, comparing it with commercial adhesives through four-point bending tests on six beam specimens. Crack propagation, load-bearing capacity, and beam displacement under monotonic and cyclic loading were analyzed to explore key adhesive properties affecting repair performance from a structural perspective. The repair mechanism of the modified epoxy resin was examined and validated by comparing stirrup strain before and after repair. Results showed that beams repaired with the self-made adhesive had an 8.4 kN increase in initial crack load, a 13.18% reduction in mid-span deflection, and a 70.36% decrease in average strain on both sides of the crack, demonstrating better recovery from fatigue damage. The elongation at break of the adhesive affects the likelihood of re-cracking, while tensile and bonding strengths are closely related to stiffness recovery and crack expansion. The primary repair mechanism involves forming a bonding layer on the rebar, which, together with uncracked concrete, shares the stirrup’s shear force and enhances structural capacity. A shear capacity formula for repaired beams with web reinforcement was established.