Evaluation of Bond Strength Between Carbon Fiber Reinforced Polymer (CFRP) Composites with Modified Epoxy Resins and Concrete

Abstract

Rehabilitation and strengthening of concrete structures are becoming more significant in civil engineering applications. The use of externally bonded Fiber Reinforced Polymers (FRP) is one of the methods to strengthen and rehabilitate reinforced concrete members, providing noticeable improvement to their capacity in resisting load. Carbon Fiber Reinforced Polymer (CFRP) is used along with epoxy resins to evaluate the bond strength of two commercially available epoxies (EPON 828 and EPON 862) between CFRP and concrete. In addition, three new combinations that resulted from mixing the two epoxies were examined. The mechanical properties of epoxy resins are significantly weaker than this of the CFRP making the epoxy characteristics the determining factor in the quality of the bond strength. Three-point flexural test was conducted to examine the bond strength between the CFRP composites and concrete. Further, differential scanning calorimetry was conducted to examine the glass transition temperature of the resultant epoxies. The results showed that the optimum composition was a mixture of 70% of epoxy 828 and 30% of epoxy 862. Therefore, achieving better bond strength and high glass transition temperature, resulting in CFRP composite with higher fire resistance.