Residual capacity and post-heating response of multiple strengthening approaches using CFRP

The application of fiber reinforced polymer (FRP) in structural rehabilitation and post-fire rehabilitation is not the optimum solution for many cases as it is challenged in many situations by engineers and building authorities due to the suboptimal thermal performance of FRP material. Compared with other mechanical and durability behaviors, fewer studies have been conducted on the effect of elevated temperatures on FRP-related structures. This paper presents multiple approaches for strengthening using a unidirectional carbon fibre along with commercially-available epoxy and cement mortar as a matrix, to assess the feasibility of using such jacketing schemes under heating conditions and for post-heating rehabilitation. First, the feasibility and the limits for reusing the heat-damaged fabric after matrix decomposition are investigated along with a trial for enhancing the decomposition temperature for the used epoxy. For 500 ⁰C exposure, the epoxy matrix was completely decomposed, as illustrated in Figure 1. The matrix decomposition eliminated composite action through full debonding. Consequently, the fabric was cleaned from epoxy debris and reused with a new layer of epoxy (i.e., to investigate reusing feasibility upon severe fabric oxidation). Secondly, a new strengthening technique is introduced using a mechanical anchor with a spiral wrapping configuration to compensate for the loss of composite action upon heating. Further, the feasibility of using high-temperature paint to prevent matrix decomposition is also introduced (i.e., through creating a vacuum environment for the FRP scheme), along with an investigation of enhancing decomposition temperature through introducing inorganic additives. Finally, Recommendations for future work in this area are presented.