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在实际工程中,钢筋混凝土中的钢筋是在氯盐侵蚀和外荷载耦合作用下服役并劣化的。重点研究了氯盐侵蚀和外荷载耦合作用对加速钢筋锈蚀的规律和机理,系统测试了在耦合作用下钢筋腐蚀速度并预测了混凝土保护层开裂时间。试件为内置4根钢筋的混凝土棱柱(普通钢筋混凝土试件和矿渣取代20%水泥的高性能混凝土试件)。运用电化学方法(腐蚀电位、线性极化和电化学阻抗)对混凝土内的钢筋进行了腐蚀程度与状况试验。结果表明:在短期测试期内(8个月),弯曲荷载能明显增加普通混凝土试件中的钢筋锈蚀速度,缩短保护层开裂时间;而对于高性能混凝土试件,弯曲荷载作用则不甚明显。
In practical engineering, steel bars in reinforced concrete are served and deteriorated under the coupling of chloride salt erosion and external load. In this paper, the corrosion mechanism and the mechanism of corrosion of steel bars by coupling corrosion of chloride salt and external load are studied emphatically. The corrosion speed of steel bars under coupling is systematically tested and the cracking time of concrete cover is predicted. The test piece is a concrete prism with four reinforcing bars (ordinary reinforced concrete specimen and high performance concrete specimen with slag replacing 20% of cement). Electrochemical methods (corrosion potential, linear polarization and electrochemical impedance) were used to test the corrosion degree and condition of steel bars in concrete. The results show that in the short term (8 months), the bending load can significantly increase the corrosion rate of steel bars in ordinary concrete specimens and shorten the cracking time of the protective layer; while for high performance concrete specimens, the bending load is not obvious .