盐冻融环境下钢筋混凝土结构锈蚀寿命预测  

Prediction for corrosion life of reinforced concrete structures under salt freeze-thaw environment

作　　者：彭艳周 高军[1,2] 徐港 李想 PENG Yanzhou;GAO Jun;XU Gang;LI Xiang(Hubei Key Laboratory of Disaster Prevention and Mitigation, China Three Gorges University, Yichang 443002, China;College of Civil Engineering & Architecture, China Three Gorges University, Yichang 443002, China)

机构地区：[1]三峡大学湖北省防灾减灾重点实验室,湖北宜昌443002 [2]三峡大学土木与建筑学院,湖北宜昌443002

出　　处：《水利水电科技进展》2019年第3期44-49,共6页Advances in Science and Technology of Water Resources

基　　金：湖北省自然科学基金(2018CFB642);国家自然科学基金(51379111)

摘　　要：针对北方海洋环境冻融作用和氯离子侵蚀对钢筋混凝土结构的服役寿命的影响,基于Fick第二定律,建立了混凝土内综合考虑时间、温度、湿度、氯离子结合和冻融损伤效应的氯离子传输模型,并运用该模型对青岛海湾大桥桥墩混凝土进行了结构锈蚀寿命预测。结果表明:混凝土构件中钢筋对氯离子的传输具有明显的阻滞效应,氯离子在靠近保护层一侧的钢筋表面累积,而远离保护层一侧钢筋表面会产生浓度迟滞;角区较非角区钢筋表面氯离子浓度峰值更高,且浓度峰值随侵蚀时间延长而增大;角区钢筋表面氯离子浓度分布形式随侵蚀时间而变,初期钢筋表面氯离子浓度峰值在钢筋距构件正、侧表面最近处,后期转向两侵蚀面对角处;较无盐冻融环境而言,其他条件相同时,经历冻融循环作用后混凝土结构的锈蚀寿命显著降低,且角区与非角区钢筋锈蚀寿命的差异明显增大。Freeze-thaw action and chloride corrosion both have influences on the service life of reinforced concrete structures under northern marine environment. Based on the Fick’s second law, a model for chloride ion migration within concrete, in which the effect of time, temperature, humidity, chlorine binding capacity and the freeze-thaw damage effect had been taken into account, was established in this paper. The model was used to predict the corrosion life for the reinforced concrete piers of the Qingdao Bay Bridge. The results show that rebars inside concrete members have an obvious blocking effect on chloride ion migration. Chloride ions are likely to accumulate on the surface of the steel bar near the protective layer while concentration retardation appears on the surface of the steel bar far away from the protective layer. The peak chloride concentration in the corner region is higher than that in the non-corner region of a concrete member, and the peak values rise with the erosion time. The distribution of chloride concentration around the rebar in the inner corner of the member varies with the erosion time. At the beginning of the erosion, the peak chloride concentration occurs on the surface of the rebar perpendicular to the eroded surface, and then, it turns to appear at the diagonal of the two eroded surfaces. Compared the results in the non-salt freeze-thaw environment, the corrosion life of the concrete structure is dramatically reduced after a freeze-thaw cycle in salt environment, and the distinction of the corrosion life of the concrete component between the corner and non-corner areas also significantly increases.

关 键 词：混凝土结构 冻融损伤 氯离子 扩散 寿命预测 

分 类 号：TU528.1[建筑科学—建筑技术科学]