高地热环境多因素影响混凝土模拟孔溶液中钢筋腐蚀行为  

Corrosion Behavior of Steel Bars in Simulated Pore Solution of Concrete Under High Geothermal Environment

作　　者：王艳 吴杰[1] 张少辉 牛荻涛 WANG Yan;WU Jie;ZHANG Shaohui;NIU Ditao(College of materials science and engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;State Key Laboratory of Green Building in Western China,Xi'an University of Architecture and Technology,Xi'an 710055,China;School of civil engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China)

机构地区：[1]西安建筑科技大学材料科学与工程学院,西安710055 [2]绿色建筑全国重点实验室,西安建筑科技大学,西安710055 [3]西安建筑科技大学土木工程学院,西安710055

出　　处：《硅酸盐学报》2024年第11期3583-3593,共11页Journal of The Chinese Ceramic Society

基　　金：国家优秀青年科学基金(52222806);陕西省杰出青年科学基金(2022JC-20);国家自然科学基金(52078413)。

摘　　要：高地热环境隧道衬砌混凝土中温度、孔溶液pH值、侵蚀离子的共同作用引发钢筋锈蚀。通过模拟混凝土孔隙液,研究了环境温度(20℃和60℃)、孔溶液pH值(12.55、12.15、11.75)和侵蚀离子种类(Cl^(-)、SO_(4)^(2-)和Cl^(-)、SO_(4)^(2-)复合)共同作用下,钢筋开始锈蚀的临界离子浓度及其锈蚀行为。结果表明:氯盐侵蚀时,温度为60℃、pH值为12.55的饱和混凝土模拟液中,钢筋锈蚀的临界氯离子浓度为0.04~0.06 mol/L;当pH值降低到12.15和11.75时,钝化膜稳定性下降,临界氯离子浓度降低到0.03~0.05 mol/L和0.02~0.04 mol/L。硫酸盐侵蚀钢筋的锈蚀诱导期更长,温度为60℃、pH值为12.55、12.15时,钢筋锈蚀的硫酸根浓度阈值相差不大,在0.06~0.08 mol/L之间;当pH值降低到11.75时,硫酸根离子浓度阈值为0.05~0.08 mol/L。硫酸盐与模拟孔溶液中Ca(OH)_(2)的反应生成石膏,其覆盖在钢筋表面对钢筋锈蚀有延缓作用,因此温度与pH值对SO_(4)^(2-)引起的锈蚀浓度阈值影响较小。Cl^(-)、SO_(4)^(2-)复合作用下,SO_(4)^(2-)会排斥吸附在电极表面的Cl^(-),并与Ca^(2+)反应生成CaSO_(4),覆盖在钢筋表面使钝化膜致密,延缓了钢筋锈蚀速度。pH值为12.55、12.15时,SO_(4)^(2-)分别达到0.03 mol/L和0.04 mol/L时对Cl^(-)引起的钢筋腐蚀具有缓蚀作用,然而当pH值为11.75时,SO_(4)^(2-)对Cl^(-)引起的钢筋腐蚀无缓蚀作用。Introduction The corrosion of steel bar in tunnel lining concrete under high geothermal environment is the result of the combined effect of temperature,pH value of pore solution,and erosion ions.In this paper,the critical ion concentration and corrosion behavior of steel bar under the combined action of ambient temperature(20℃and 60℃),pH value of pore solution(12.55,12.15,and 11.75)and erosion ions(Cl^(-),SO_(4)^(2-),and Cl^(-),SO_(4)^(2-)composite)were studied by simulating concrete pore solution.The results show that the critical chloride concentration of steel corrosion is 0.04-0.06 mol/L in the saturated concrete simulated solution with temperature of60℃and pH of 12.55 during chloride corrosion.The stability of the passivation film decreased when the pH value decreased(12.15and 11.75),and the corresponding critical chloride ion concentration also decreased(0.03-0.05 mol/L and 0.02-0.04 mol/L,respectively).The corrosion induction period of steel bar becomes longer when the steel bar is eroded by single sulfate.The threshold value of sulfate ion concentration is between 0.06-0.08 mol/L when the temperature is 60℃and the pH value is 12.55 and 12.15,and it becomes 0.05-0.08 mol/L when the pH value decreases to 11.75.There is no significant difference in the sulfate concentration threshold of steel corrosion,because the gypsum covers the steel surface and delays the steel corrosion which formed by the reaction of sulfate with Ca(OH)_(2)in the simulated pore solution.Therefore,temperature and pH value have not significant effect on the corrosion concentration threshold caused by SO_(4)^(2-).Under the combined action of Cl^(-)and SO_(4)^(2-),SO_(4)^(2-)will repel the Cl^(-),and it reacts with Ca^(2+)to form CaSO_(4),which covers the surface of steel bar,densifies the passive film,and slows down the corrosion rate of steel bar.When the pH value is 12.55 and 12.15,SO_(4)^(2-)reaches 0.03 mol/L and 0.04 mol/L respectively,which can inhibit the corrosion of steel bar caused by Cl^(-).However,when the pH value is

关 键 词：高地热环境 钢筋锈蚀 高温 孔溶液pH值 氯盐-硫酸盐侵蚀 

分 类 号：TU528[建筑科学—建筑技术科学]