A Study on Limit State for Steel Corrosion of Concrete Members with Ground Granulated Blast-Furnace Slag

本研究的目的是确定碳化速度和氯离子渗透速度的混凝土与粒化高炉矿渣（GGBFS），并探讨碳化和盐损害的钢筋腐蚀极限状态的影响。采用电子探针分析（EPMA）技术，获得了氯离子的详细分布。在实验基础上研制了一种监测钢筋锈蚀的传感器。高置换率、高细度和长时间湿养护可提高抗碳化和抗氯离子渗透性。高强混凝土的氯离子渗透在表层受到抑制，碳化深度和氯离子渗透深度几乎不增加。只有掺矿渣微粉的混凝土才能抵抗氯化钙等防冻剂。此外，矿渣微粉还可以延缓碳化与氯离子渗透、碳化与酸雨的联合劣化。其次，总结了国内外对钢筋腐蚀极限状态的研究和暴露试验的结果。结果表明，氯离子浓度、风速、温度、温湿度偏差是影响混凝土腐蚀的重要因素，并通过实验验证了利用电子探针（EPMA）获取混凝土中氯离子详细分布的方法。电子探针法测定结果与常规滴定法测定结果吻合较好。最后，对在实验基础上研制的传感器进行了实用性检验。阐明了传感器钢丝腐蚀和电阻增大的原因，并对传感器在结构上的实际应用进行了前景展望。

The purpose of this study is to determine the carbonation speed and the penetration speed of chloride ion of concrete with ground granulated blast-furnace slag (GGBFS) and to investigate the effects of carbonation and salt damage to the limit state of steel corrosion. Electron probe micro analysis (EPMA) was performed to obtain the detailed distribution of chloride ion. A sensor to monitoring steel corrosion was made on an experimental basisFirstly, normal-strength and high-strength concrete with GGBFS were tested in laboratories. High replacement ratio, high fineness, and long wet curing increased resistance to carbonation and chloride ion penetration. Chloride ion penetration of high-strength concrete was restrained at surface layer, and carbonation depth and penetration depth of chloride ion hardly increased. Only the concrete with GGBFS could resist to an antifreezing agent such as calcium chloride. Moreover, GGBFS could delay combined deterioration of carbonation and chloride penetration, and of carbonation and acid rain.Secondly, past researches on the limit state of steel corrosion and the results of exposure tests were summarized. It was found that the important factors to dominate corrosion were concentration of chloride ion, wind velocity, temperature, the deviation of temperature and humidity.Then, a method using EPMA to obtain the detailed distribution of chloride ion in concrete was verified experimentally. The results by EPMA method well agreed with the results by usual titration method.Lastly, practicality of the sensor made on experimental basis was examined. The condition that the steel wire of sensor corroded and electric resistance of it increased was clarified, and there is prospect of a practical application of the sensor for structures.