Bond behaviour between NSM CFRP strips and concrete at high temperature using innovative high-strength self-compacting cementitious adhesive (IHSSC-CA) made with graphene oxide

Strengthening of reinforced concrete (RC) structures using the near-surface mounted (NSM) fibre reinforced polymer (FRP) method is becoming an attractive technique for upgrading the existing structural elements. The exposure of the NSM FRP strengthening system to high temperatures greatly affects the bond between FRP, adhesive material and the concrete substrate. Organic adhesives are widely used in the NSM strengthening technique. However, their low fire resistance is a major drawback. This study investigates the performance of NSM carbon FRP strengthening technique using single-lap shear tests (pull-out tests) with innovative high-strength self-compacting cementitious adhesive (IHSSC-CA) under high temperatures. Graphene oxide and cementitious materials were used to synthesise the IHSSC-CA. Single-lab shear tests were conducted on NSM strengthened specimens which were exposed to high temperatures of 800 °C. The results obtained from the pull-out tests signifies that the samples made with IHSSC-CA were less affected by high temperature, and maintain considerable residual bond strength. Theoretical equations are proposed to simulate the effect of high temperature on bond strength.