Performance evaluation of CFRP strengthening system protected with heat-resistant coatings

The strengthening effect of carbon fiber-reinforced polymer (CFRP) will degenerate at a high temperature. The present study explored the efficacy of various heat-resistant coatings (non-intumescent, intumescent, and mixed) in enhancing the thermal resistance of CFRP-strengthened concrete systems. Utilizing a cone calorimeter, these coated systems were placed under high temperatures and subsequently evaluated their mechanical properties through single-shear tests. Results revealed that all the coated specimens exhibited a notable reduction in the adhesive layer’s temperature in comparison with the unprotected specimens, and the heat transfer rate was reduced by over 50% after coating. It also be determined that the mechanical properties of the reinforcement system could be restored after cooling to ambient temperatures, provided the adhesive layer’s temperature remained below 200°C during heating. We further delineated the relationship between bearing capacity and maximum adhesive temperature. Moreover, this study suggests a substantial mitigation of fire hazards associated with the reinforcement system upon application of these coatings. Among all the tested variants, the mixed coating was preferred, attributed to its minimal thickness, appropriate thermal insulation properties, and minimal hazard risk. This work provides information on optimizing CFRP design and enhancing the thermal resistance of this material in real application.