Flexural behavior of reinforced concrete beams externally strengthened with CFRP sheets bonded with an inorganic matrix

Externally bonding fiber reinforced polymer (FRP) sheets with an epoxy resin is an effective technique for strengthening and repairing reinforced concrete (RC) beams under flexural loads. In this study, a total of eight RC beams was tested and analyzed: one control beam and seven beams reinforced with three to six layers of carbon fiber sheets bonded by an inorganic epoxy. All specimens were subjected to a four-point bending test under load control while load, deflection, mid-span strain and failure mode were recorded up to failure. It is found that the load carrying capacity increases with the number of layers of carbon fiber sheet up to 170.2% of the control beam strength. For three and four layers of FRP reinforcement, the beams failed by rupture of FRP, while beams with five and six layers of FRP reinforcement failed by FRP delamination. The ductility of the FRP strengthened beams is greatly reduced compared to the control beam. A moment deflection model is developed and used on the tested beams in current and other similar studies. Good agreement between experiment and prediction values is achieved.