Assessment of Glass-Fiber-Reinforced Polymer (GFRP)–Concrete Interface Durability Subjected to Simulated Seawater Environment

Fiber-reinforced polymer (FRP)-retrofitted concrete structures are extensively utilized, and they have attracted growing research interest due to their combined performance in marine environments. To investigate the effect of seawater exposure, a total of 20 single-shear GFRP (glass-FRP)-bonded concrete structures were tested. Three corrosion conditions, i.e., exposure to single-salinity and triple-salinity seawater through wet–dry cycles as well as continuous immersion in triple-salinity seawater, were simulated and tested. The minimum shear strength (13,006 N) was tested using specimen B150-T-DW-90, which was cured in triple-salinity seawater with wet–dry cyclic exposure. The results of the shear strengths, load–displacement curves, interfacial shear stresses, and fracture energies indicated that seawater exposure degraded the bonding strength of the GFRP–concrete interface. Notably, the wet–dry cycles in triple-salinity seawater resulted in the most significant interface degradation, which could exacerbate with prolonged exposure. By introducing a parameter, the residual coefficient α, a new strength calculation model for GFRP–concrete exposed to a seawater environment was proposed and discussed.

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