基于电渗作用的替代孔溶液法修复氯离子侵蚀钢筋混凝土结构研究

It is essential for the reinforced concrete structure contaminated by chloride ions to carry out a repair so as to prolong its service life. To date, the electrochemical chloride exaction is the only nondestructive repair method that can be applied to remove the aggressive chloride ions, which lead to the corrosion of reinforcement in concrete. Despite of this, the application of electrochemical chloride exaction is limited for the fact that it exerts negative effects on the properties of reinforcement and interfaces between the concrete and reinforcement. To overcome this problem, a novel electrochemical repair method has been firstly put forward in this project. It includes that a metal material is added as the cathode. Besides, the pore solution with chloride ions is expelled from the pores of concrete, and the pore solution without chloride ions outside the concrete is driven into the pores of concrete by electroosmosis. A systematical investigation on the influencing factors, regularities and regulating methods of Zeta potential of pore wall is to be conducted from two aspects, namely, concrete performance and treatment process. Besides, it is to examine the effectiveness of this method by the measurements of ionic composition, reinforcement corrosion and physical-mechanical properties of concrete structure, and to investigate the mechanism of this method by the characterization of microstructure. Furthermore, it is to monitor continuously the corrosion potential and corrosion current density of reinforcement so as to decide the long-term durability of chloride contaminated reinforced concrete after the application of this method and its improvement measures. The obtained results will lay experimental and theoretical fundaments for the application of this method. Owing to the fact that it involves concrete technology, colloid and superficial chemistry and electrochemistry, and such a method is suitable not only for the ordinary reinforced concrete structure, but also for the prestressed reinforced concrete structure, this project has great significance in theory and practice.

对于已受氯离子侵蚀的钢筋混凝土结构，为了延长使用寿命，需进行修复处理。电化学脱盐是目前唯一能去除氯离子，由此从根源上进行此修复的无损方法，但是，它对钢筋与钢筋/混凝土界面性能有负作用，严重制约其应用。为了克服传统电化学修复方法这一缺陷，本项目首次提出增设一个外部阴极，通过电渗驱除被污染孔溶液，促使外部纯净孔溶液进入孔隙，由此去除氯离子，并恢复钢筋钝态的新方法。拟从混凝土特性与处理工艺研究氯盐环境下混凝土结构孔壁Zeta电位的影响因素、变化规律与调控方法；通过测试组成离子、钢筋腐蚀与混凝土结构物理力学性能，研究该方法修复效果；通过微结构分析，研究作用机理；持续监测钢筋腐蚀电位与腐蚀电流密度，研究长期耐久性，探索提升措施，为实际应用该方法奠定理论与试验基础。本项目系混凝土科学、胶体表面化学与电化学的集成，研究成果可广泛用于普通与预应力钢筋混凝土结构氯离子腐蚀修复，具有重要理论意义和实用价值。

氯盐环境下混凝土中钢筋腐蚀主要诱因是氯离子侵蚀，因此去除混凝土中具有侵蚀性的氯离子是修复此处混凝土中钢筋腐蚀的一个有效途径。传统的电化学脱盐技术对钢筋与钢筋/混凝土界面性能有负作用，严重制约其应用。为了克服传统电化学修复方法的这一缺陷，本项目首次提出增设一个外部阴极，通过电渗驱除被污染孔溶液，促使外部纯净孔溶液进入孔隙，由此去除氯离子，并恢复钢筋钝态的新方法。拟从混凝土特性与处理工艺研究氯盐环境下混凝土结构孔壁Zeta 电位的影响因素、变化规律与调控方法；通过测试组成离子、钢筋腐蚀与混凝土结构物理力学性能，研究该方法修复效果；通过微结构分析，研究作用机理；持续监测钢筋腐蚀电位与腐蚀电流密度，研究长期耐久性，探索提升措施，为实际应用该方法奠定理论与试验基础。研究结果表明：氯盐环境下混凝土结构孔壁Zeta 电位受到水胶比、矿物掺合料及有机添加剂的明显影响；与传统的电化学除盐技术相比，本项目所提的除盐方法提高了除盐效率，避免了析氢反应的发生，钢筋表面附近没有发生OH-、Na+和K+的集聚，由此能够降低碱集料反应和碱性腐蚀发生的风险，此外，加速钢筋在电化学除盐处理后的再钝化；阳离子和阴离子表面活性剂分别会提高与降低水泥浆体吸附氯离子的能力，二者都提高电化学除盐的除盐效率；经处理的试件再次处于氯盐环境中时，表面活性剂的使用能够延长腐蚀电位降低和腐蚀电流密度升高的时间，主要原因是电解质溶液中的表面活性剂分子进入到砂浆孔隙中，会附着在水化产物或集料上，在孔隙中聚集形成丝状或网状结构，填充孔隙，使孔隙率降低、大孔减少。本项目为钢筋混凝土结构氯离子腐蚀修复的提供一个全新途径，对于延长混凝土结构服役寿命具有重要意义。项目共发表论文28篇，其中SCI检索18篇，EI检索5篇，申请国家发明专利13项（授权8项）。