Evaluating the high-temperature endurance of FRP-strengthened concrete using an innovative insulation system: Experimental investigation

Abstract

Extensive research on fiber-reinforced polymer (FRP) composites has led to the presumption that this material is an effective solution for repairing and strengthening the reinforced concrete (RC) elements. The use of FRP significantly enhances the carrying capacity of elements under structural loads. However, the poor fire performance of this material poses a major concern, particularly in buildings. High temperature exposure can damage the adhesive bonding of polymer matrices and degrade their strength. Therefore, the use of thermal insulation is essential to ensure the safety of FRP-strengthened buildings. This study experimentally investigated the effectiveness of a recently developed thermal insulation system, “DYMAT® FIREWRAP”, in protecting the carbon and glass FRP wrapped concrete specimens. The tested insulation system comprised two different materials namely DYMAT® RS and Dymatherm. During the experiments, 50 concrete specimens with different strengthening and insulation configurations were prepared and exposed to high temperatures of 200 °C and 400 °C. The results highlight the importance of using thermal insulation on FRP repaired concrete elements. After high temperature exposure of 200 °C, the compressive strength losses of CFRP wrapped specimens were 12% lower than those of the non-insulated specimens. For GFRP strengthened specimens, the strength loss was 17% less than that for the non-insulated specimens. After high temperature exposure of 400 °C, the CFRP wrapped specimens experienced 27% less reduction in their compressive strength, and the strength loss for GFRP wrapped specimens was reduced by 32%. Among the considered configurations, the presence of the RS material as an inner layer played a major role in protecting the epoxy from deterioration. Dymatherm provided adequate protection; however, the number of layers did not significantly affect the high temperature endurance of the specimens.