海洋水位变动区混凝土横向裂缝宽度对钢筋混凝土构件耐久性影响

Effect of concrete cracks on durability of reinforced concrete structures exposed in ocean tidal zone

通过半电池电位法并结合混凝土破型手段,研究了人工海水模拟试验箱和湛江港暴露试验站水位变动区混凝土裂缝宽度对混凝土内钢筋腐蚀速率及钢筋锈蚀率的影响,试验结果表明:混凝土内钢筋发生锈蚀的试验龄期随裂缝宽度增大而缩短,且钢筋的锈蚀率随裂缝宽度增加而增大,裂缝宽度由0.15 mm增加至0.60 mm时钢筋锈蚀率由0.35%增加至10.4%,高碱性环境下混凝土内钢筋表面钝化膜破坏后可短暂自修复。混凝土配合比差异对钢筋锈蚀率的影响并不显著,裂缝宽度影响了钢筋/混凝土界面的氧气含量,导致了钢筋腐蚀速率出现差异。

The influence of concrete crack width on corrosion rate and corrosion ratio of steel bar in reinforced concrete structures exposed in ocean tidal zone of artificial seawater simulated machine and Zhanjiang Port Exposure Station was determined by means of half-cell potential method and breaking method.The results shows that the corrosion time of steel bar decreases but the corrosion ratio of steel bar increases with the increase of concrete crack width.When the crack width increases from 0.15 mm to 0.60 mm,the corrosion rate of steel bar increases from 0.35%to 10.4%.The passive film of steel bar can repair itself after being damaged in high alkaline environment.The difference of concrete mix ratio has no significant effect on the corrosion ratio of steel bars.The crack width affects the oxygen content of the steel/concrete interface,which leads to the difference of corrosion rate of steel bars.