Effects of freeze-thaw and dry-wet conditionings on the mode-I fracture of FRP-concrete interface bonds

The significant attention devoted to rehabilitation of civil infrastructure has presented a unique opportunity for development of combined fiber-reinforced plastic (FRP) and concrete materials, which can provide longer service-life and lower life-cycle costs than conventional materials. However, there is a concern with the long-term reliable performance and durability of the FRP-concrete interface bond, which is critical to the application of this technology. In this study, a work-of-fracture method using three-point bend beam (3PBB) specimen is adapted to evaluate the mode-I fracture and durability of FRP-concrete bonded interfaces. The effects of freeze-thaw and wet-dry cycles on the mode-I fracture of FRP-concrete bonded interfaces were studied, and the test results indicated that the fracture energy under freeze-thaw and wet-dry cycles both decreased as the number of cycles increased. The examination of interface fractured surfaces along the bond lines under various freeze-thaw and wet-dry cycles revealed that a transformation of failure mode occurred, from the cohesive fracture of concrete under no environmental exposure to adhesive interface failure at high cyclic conditioning. The deterioration of FRP-concrete interface under freeze-thaw and wet-dry cycles was founded relatively pronounced.