CFRP Repair of Corrosion-Damaged Bond Region

ABSTRACT: Structures such as bridges and marine structures are subjected to repeated loading.At the same time those structures are prone to corrosion. Corrosion of reinforced concrete (RC) structures is a multi-billion dollar problem that affects structures worldwide. One of the main consequences of corrosion in RC is the deterioration of the bond between the concrete and the steel. A recent study reported by the authors showed that a corrosion level of only 5% mass loss decreased the fatigue bond strength by about 12%. Research conducted over the past few years has shown that reinforcement with fiber reinforced polymer (FRP) sheets can provide aviable solution to the corrosion-bond problem. This paper examines the effect of strengthening with FRP sheets on the bond strength of corroded steel bars in concrete beams subjected to repeated loading. Twenty anchorage-beams were tested. The beam dimensions were 152 x 254 x2000 mm. The variables were the level of corrosion (5% and 9% measured mass loss) and the load range applied. The repeated loading caused bond fatigue failure in unwrapped uncorroded beams, but some wrapped corroded beams failed by fatigue of the steel at a corrosion pit. The slip versus number of cycles curves for the wrapped corroded beams differed from that of the uncorroded unwrapped beams. Repairing with CFRP sheets increased the fatigue bond strength of wrapped beams corroded to 5% and 9% mass loss by 11% and 4% respectively above that of the uncorroded unwrapped beams