Residual Performance of Heat-Damaged CFRP Jackets in FRP-Confined Concrete

This paper presents experimental work that was conducted to investigate the feasibility of and set the limits for the reuse of fiber-reinforced polymer (FRP) jacketing after exposure to heat damage. In this study, a novel framework is proposed for addressing the suboptimal thermal performance of FRP materials in strengthening concrete. The experimental work outlined herein pursues two primary objectives: (1) to examine the compressive behavior of FRP-confined concrete cylinders under the effect of broad elevated temperature exposure, and (2) to study the feasibility of restoring the effectiveness of the heat-damaged carbon fiber–reinforced polymer (CFRP) jackets by postheating rehabilitation. The behavior and limits of the respective confinement scenarios are examined after exposure to elevated temperatures up to 650°C. A total of 40 concrete cylinders were tested under various FRP wrapping scenarios and heated under a steady-state heating regime. The results indicated that the FRP jacketing effectiveness could be maintained up to 350°C exposure (close to the matrix decomposition temperature). However, upon reaching and exceeding the matrix decomposition temperature, the whole system collapsed due to the complete loss of contact. In such cases, the carbon fabric was cleaned and reapplied with a new layer of epoxy, which improved the performance significantly, with an enhancement ratio of 1.82. In this work, the reuse concept was studied in detail to maximize/explore the sustainability potential of FRP jackets under heat/fire damage conditions. Furthermore, the results show that the success of such a jacket reapplication technique depends highly on the level of fabric oxidation. The results also established explicit limits for exposing FRP jacketing to elevated temperatures and the feasibility of reusing the heat-damaged fabric, along with the practicality of restoring the concrete’s original strength. Finally, the findings were further implemented to construct a new framework for evaluating FRP jacketing serviceability and reuse limits.