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| Experimental research on effect of bidirectional electromigration rehabilitation on reinforced concrete—Concentration changes of inhibitor, chloride ions and total alkalinity |
| JIN Wei-liang1,2, HUANG Nan1, XU Chen1, MAO Jiang-hong2 |
| 1. Institute of Structural Engineering, Zhejiang University, Hangzhou 310058, China; 2. Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China |
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Abstract An amine-based corrosion inhibitor for steel in aqueous media was introduced into reinforced concrete specimens mixed with chloride through a novel method called bidirectional electro-migration rehabilitation (BIEM) in order to improve the remediation effect on chloride-contaminated reinforced concrete structures without damage. An electrical field was applied between embedded steel cathode and external anode to inject the corrosion inhibitor from external electrolyte and extract the chloride ions from the concrete cover zone. Considering the applied current density, duration of electrolysis, water/cement ratio and initial chloride content, the concentration profiles of the corrosion inhibitor and the chloride ions as well as the profiles of total alkalinity within the concrete were determined to evaluate the effectiveness of BIEM by means of organic elemental analyzer and automatic potentiometric titrator. Electrochemical chloride extraction (ECE) was applied to similar concrete surfaces as control experiments. It was found that chloride content decreased and alkalinity increased after the treatment. The inhibitor concentration around the embedded steel was adequate to provide corrosion protection under proper conditions. The effectiveness of BIEM increased as current density and/or treatment duration and/or water/cement ratio increased. However, the initial chloride content within concrete had little effect on the efficiency of the electrolysis. Results also showed that ECE and BIEM had different influences on chloride extraction and alkalinity increase. After BIEM treatment, chloride distribution appears increasing trend from inside to outside of concrete cover; but for ECE treatment, chloride content is in uniform distribution.However,the total alkalinity seems similar after BIEM and ECE treatment.
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Published: 01 September 2014
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双向电渗对钢筋混凝土修复效果的试验研究——保护层阻锈剂、氯离子和总碱度的变化规律
为提高氯盐侵蚀环境下钢筋混凝土结构的无损修复效果,对受氯盐侵蚀的钢筋混凝土试件采用双向电渗技术,在排出氯离子的同时向混凝土保护层内引入阻锈剂.为考察该技术的修复效果,采用有机元素分析法和自动电位滴定法,结合电流密度、通电时间、水灰比、初始氯盐掺量4个影响因素,研究混凝土保护层内阻锈剂、氯离子分布的变化情况,并对保护层的总碱度进行测量；同时设置电化学除氯组作为对照.结果表明：双向电渗处理后试件保护层内氯离子含量降低,总碱度提高；通过对各参数的合理控制,阻锈剂迁移至钢筋表面的浓度足以起到较好的阻锈效果.双向电渗的效果随电流密度、通电时间、试件水灰比的增加而提高,而受初始氯盐掺量的影响较小.双向电渗在对混凝土氯离子迁出和总碱度提高的效果方面与电化学除氯有所差异.在双向电渗后，Cl-质量摩尔浓度沿着保护层厚度方向由内向外成增高趋势；而电化学除氯后整个保护层内Cl-质量摩尔浓度分布相对均匀.对保护层碱度变化来说，两种处理方式效果接近.
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