混凝土中氯离子–硫酸根离子耦合传输模型
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摘要
针对氯盐–硫酸盐耦合作用环境下混凝土及其结构的耐久性退化问题,根据硫酸根离子扩散反应机理及氯离子吸附结合机制,利用Fick定律及质量守恒定律,建立了混凝土中氯离子–硫酸根离子的耦合传输模型;以水泥砂浆替代混凝土,开展了混凝土圆柱体试件在单一氯盐、单一硫酸盐及复合氯盐–硫酸盐溶液中的浸泡腐蚀试验,测试了不同浸泡时间时试件中氯离子和硫酸根离子含量,并与模型计算结果进行了对比分析。结果表明,模型计算结果与实验测试结果基本一致;耦合传输过程中氯离子和硫酸根离子之间存在相互抑制作用,且复合溶液中试件内氯离子和硫酸根离子含量分别低于单一氯盐和单一硫酸盐溶液中试件的氯离子和硫酸根离子含量。
To solve the problem of durability degradation of concrete and structure under the environment of chloride-sulfate coupling corrosion,the coupling transmission model of chloride ion-sulfate ions in concrete,which is based on the mechanism of sulfate ion diffusion reaction and chloride ion adsorption bonding mechanism,was established by utilizing Fick's law and mass conservation law.The immersion tests of cement mortar cylindrical specimens which substituted for concrete specimens were carried out in three kinds of solutions containing single chlorine,single sulfate and compound chloride-sulfate respectively. The contents of chloride ion and sulfate ion in the specimen after different soaking time were measured and compared with the calculated results of the model. The result shows that the calculated results are consistent with the experimental results,and there is mutual inhibition between chloride ion and sulfate ion in couple transmission process which was testified by that the content of chloride ion and sulfate ion in the specimen in the compound solution is lower than those in the single chlorine solution and the single sulfate solution respectively.
To solve the problem of durability degradation of concrete and structure under the environment of chloride-sulfate coupling corrosion,the coupling transmission model of chloride ion-sulfate ions in concrete,which is based on the mechanism of sulfate ion diffusion reaction and chloride ion adsorption bonding mechanism,was established by utilizing Fick's law and mass conservation law.The immersion tests of cement mortar cylindrical specimens which substituted for concrete specimens were carried out in three kinds of solutions containing single chlorine,single sulfate and compound chloride-sulfate respectively. The contents of chloride ion and sulfate ion in the specimen after different soaking time were measured and compared with the calculated results of the model. The result shows that the calculated results are consistent with the experimental results,and there is mutual inhibition between chloride ion and sulfate ion in couple transmission process which was testified by that the content of chloride ion and sulfate ion in the specimen in the compound solution is lower than those in the single chlorine solution and the single sulfate solution respectively.
引文
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[15] Suresh A K,Ghoroi C. Solid-solid reactions in series:a modeling and experimental study[J]. Aiche Journal,2009,55(9):2399-2413.
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[18] JTJ 270—98,水运工程混凝土试验规程[S].
[19] GB/T 50123-1999,土工试验方法标准[S].
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[21]王佳林.硫酸盐–氯盐耦合作用下混凝土耐久性试验分析及数值模拟[D].南京:南京理工大学,2017.
[22] Andrade C,Díez J M,Alonso C. Mathematical modeling of a concrete surface “skin effect”on diffusion in chloride contaminated media[J]. Advanced Cement Based Materials,1997,6(2):39-44.
[2] Hirao H,Yamada K,Takahashi H,et al. Chloride Binding of Cement Estimated by Binding Isotherms of Hydrates[J]. Journal of Advanced Concrete Technology,2005,3(1):77-84.
[3]施锦杰,孙伟.混凝土中钢筋锈蚀研究现状与热点问题分析[J].硅酸盐学报,2010,(9):1753-1764.
[4] Sun C,Chen J,Zhu J,et al. A new diffusion model of sulfate ions in concrete[J]. Construction and Building Materials,2013,39:39-45.
[5]冯乃谦,邢锋.混凝土与混凝土结构的耐久性[M].北京:机械工业出版社,2009.
[6]陈晓斌,唐孟雄,马昆林.地下混凝土结构硫酸盐及氯盐侵蚀的耐久性实验[J].中南大学学报(自然科学版),2012,(7):2803-2812.
[7] Al-Amoudi O S B,Maslehuddin M,Abdul-Al Y A B.Role of chloride ions on expansion and strength reduction in plain and blended cements in sulfate environments[J]. Construction and Building Materials,1995,9(1):25-33.
[8] Maes M,De Belie N. Resistance of concrete and mortar against combined attack of chloride and sodium sulphate[J]. Cement and Concrete Composites,2014,53:59-72.
[9] Chen Y,Gao J,Tang L,et al. Resistance of concrete against combined attack of chloride and sulfate under drying-wetting cycles[J]. Construction and Building Materials,2016,106:650-658.
[10] Geng J,Easterbrook D,Li L,et al. The stability of bound chlorides in cement paste with sulfate attack[J]. Cement and Concrete Research,2015,68:211-222.
[11] Stroh J,Meng B,Emmerling F. Deterioration of hardened cement paste under combined sulphate-chloride attack investigated by synchrotron XRD[J]. Solid State Sciences,2016,56:29-44.
[12] Müllauer W,Beddoe R E,Heinz D. Sulfate attack expansion mechanisms[J]. Cement and Concrete Research,2013,52:208-215.
[13]傅献彩.物理化学(第5版)[M].北京:高等教育出版社,2005.
[14] Zuo X B,Wang J L,Sun W,et al. Numerical investigation on gypsum and ettringite formation in cement pastes subjected to sulfate attack[J]. Computers and Concrete,2017,19(1):19-31.
[15] Suresh A K,Ghoroi C. Solid-solid reactions in series:a modeling and experimental study[J]. Aiche Journal,2009,55(9):2399-2413.
[16] Tixier R,Mobasher B. Modeling of damage in cementbased materials subjected to external sulfate attack. I:formulation[J]. Journal of Materials in Civil Engineering,2003,15(4):305-313.
[17] Tixier R,Mobasher B. Modeling of damage in cementbased materials subjected to external sulfate attack. II:comparison with experiments[J]. Journal of Materials in Civil Engineering,2003,15(4):314-322.
[18] JTJ 270—98,水运工程混凝土试验规程[S].
[19] GB/T 50123-1999,土工试验方法标准[S].
[20]陆金甫,关治.偏微分方程数值解法(第2版)[M].北京:清华大学出版社,2004.
[21]王佳林.硫酸盐–氯盐耦合作用下混凝土耐久性试验分析及数值模拟[D].南京:南京理工大学,2017.
[22] Andrade C,Díez J M,Alonso C. Mathematical modeling of a concrete surface “skin effect”on diffusion in chloride contaminated media[J]. Advanced Cement Based Materials,1997,6(2):39-44.