Tensile behavior of epoxy based FRP composites under extreme service conditions

A well established technique for strengthening reinforced concrete (RC) members is based on the use of externally bonded (EB) FRPcomposites. Nevertheless, limited knowledge is available on the mechanical properties of FRPcomposites at extremeservice environments. The performance of structural members strengthened with EB-FRP laminates exposed to extremeservice temperatures or freeze???thaw cycles is mainly associated to either the bond between the FRP laminate and concrete substrate, or the mechanical properties of the laminates. This paper focuses on the latter aspects and presents results on a series of tensile tests of glass and carbon FRP (GFRP and CFRP) coupon specimens exposed to temperatures ranging between ???15 and +70 °C, or after freeze???thaw cycles, including FRP specimens with different number of plies. The experimental results for GFRP specimens indicate a low influence of ply number on FRP mechanical properties, and a minor reduction of axial tensile strength and strain with increasing the temperature. Results for CFRP specimens subjected to extremeservice temperatures reflect a significant reduction of mechanical properties, while freeze???thaw cycles do not significantly influence the mechanical performance.