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纤维复材的加固技术正越来越多地被用来修复受损钢筋混凝土(RC)桥梁。而在南方湿热环境下,胶黏剂的性能退化及氯离子对RC梁的侵蚀作用,将对被修复桥梁的耐久性产生不利影响。为此对干湿循环下碳纤维布加固受损RC梁的抗弯承载力及氯离子的扩散情况进行研究。干湿循环加速老化试验包括3个月和6个月两种工况,一次干湿循环为24 h,包括湿环境(3.5%盐水浸泡)10 h和干环境(40℃热风)14 h。试验结果表明:干湿循环略为减小了加固梁的刚度,导致了混凝土与碳纤维布黏结界面的退化;干湿循环前3个月,加固梁的承载能力有明显降低,而后逐步稳定;受损RC梁裂缝附近的氯离子含量远高于其他部分;碳纤维布加固减缓了氯离子由梁底对RC梁的侵蚀,对带裂缝工作的受损梁有较好的保护作用。
Reinforcement of fiber-reinforced materials is increasingly being used to repair damaged RC bridges. In the wet and hot environment in the south, the deterioration of the adhesive properties and the corrosion effect of chloride ions on the RC beams will adversely affect the durability of the bridges being repaired. Therefore, the flexural capacity and chloride ion diffusion of damaged RC beams strengthened by carbon fiber reinforced plastic under wet-dry cycles were studied. The accelerated aging test of wet-dry cycle includes two working conditions of 3 months and 6 months. The first cycle of wet-dry cycle is 24 h, including wet environment (3.5% brine immersion) and dry environment (hot air of 40 ℃) for 14 h. The results show that the dry-wet cycle slightly reduces the stiffness of the reinforced beam, which leads to the degradation of the bonding interface between the concrete and the carbon fiber cloth. The load carrying capacity of the reinforced beam is obviously decreased 3 months before the wet-dry cycle and then gradually stabilizes. The content of chloride ion near the crack of RC beam is much higher than that of other parts. The reinforcement of CFRP slows down the corrosion of chloride ion from the beam to the RC beam and protects the damaged beam with crack.