Corrosion of steel reinforcement is one of the main durability problems facing worldwide use of reinforced concrete. This paper presents the results of an experimental study to evaluate the flexural capacity of corrosion-damaged beams repaired with carbon fiber reinforced polymer (CFRP) sheets. Ten beam specimens (150×250×1400mm) were constructed. Two specimens were neither strengthened nor corroded to serve as a reference. Two specimens were corroded and not repaired. The remaining six beams were corroded and repaired with different layers of CFRP sheets. The CFRP sheets were applied after the main reinforcing bars were corroded to the appearance of longitudinal cracks with a 0.3mm width. The experimental results show that the number of CFRP sheets affect the strength as well as the failure mechanisms of retrofitted RC beams. Furthermore, a repairing project using CFRP conducted by the Key Laboratory of Harbor and Marine Structure Durability Technology Ministry of Communications was reported to verify this strengthening method.
Corrosion of reinforcing steel causes many structures in adverse environments to experience unacceptable loss in serviceability or safety far earlier than anticipated and thus need replacement, rehabilitation or strengthening. As steel corrodes, there is a corresponding drop in the cross-sectional area. The corrosion products occupy a larger volume than the original steel which exert substantial tensile forces on the surrounding concrete and causes it to crack and spall. If corrosion cracking can be prevented or delayed, a certain degree of structural strength can be maintained in a corroding RC beam. Several rehabilitation techniques for concrete members have been identified during the last three decades. Concrete members including bridges, coastal structures, tunnel structures and parking garages, have been repaired by jacketing with new concrete in conjunction with epoxy-bonded steel plates. However, steel plates have a durability problem because of their vulnerability to corrosion.