Interfacial performance of aramid, basalt and carbon fiber reinforced polymer bonded concrete exposed to high temperature

Externally bonding fiber reinforced polymer (FRP) is an effective approach to strengthen/retrofit concrete structures. However, little is known on bond performance of FRP-bonded concrete under high temperature, impeding the application of FRP in buildings potentially subjected to fire. In this paper, the bond performance of aramid, basalt and carbon FRP-concrete subjected to high temperature (80–300 °C) has been investigated through acoustic-laser technique, macroscale fracture tests and microscale characterization. Results have shown that the deterioration percentages of both peel and shear interface fracture toughness of aramid FRP-bonded concrete are largest under high temperature, followed by carbon FRP-bonded concrete and basalt FRP-bonded concrete. The mechanisms behind different bond performance have been revealed with variations of microscale morphology and chemical decomposition. The results and findings can provide a fair comparison of thermal susceptibility and residual bond performance of various FRP-bonded systems, and contribute to designing FRP strengthening/retrofitting systems under high temperature.