【作者】 耿健；

【导师】 胡曙光； 丁庆军；

【作者基本信息】 武汉理工大学 ， 建筑材料与工程， 2008， 博士

【摘要】 地铁工程混凝土结构往往处于杂散电流与氯离子共存的腐蚀环境中，二者对混凝土耐久性劣化的相互促进作用使得这类工程混凝土面临更为严重的耐久性问题，其耐久性的劣化机理也比单因素作用更加复杂。本文围绕着杂散电流与氯离子共存环境下，钢筋混凝土的劣化特征、劣化机理以及相应的高耐久性材料制备开展了深入的系统的研究工作，其获得的研究成果对地铁等地下工程混凝土材料的耐久性设计与应用，具有重要的理论和实践指导意义。论文进行的主要工作和取得的重要成果有：通过系统研究杂散电流与氯离子共存环境下，受腐蚀钢筋电化学当量和锈蚀特征的依时变化规律，以及相应混凝土力学性能退化特点，掌握了该环境条件下钢筋混凝土的钢筋锈蚀速度快、锈蚀程度严重以及混凝土抗压强度和弹性模量失效快的劣化特征。同时采用电化学测试技术，探明了氯离子引发钢筋锈蚀极限浓度值随杂散电流强度增加而下降的变化规律，首次提出了杂散电流与氯离子共存环境下的、氯离子引发钢筋锈蚀极限浓度值的表征方法：[Cl^-]／[OH^-]=2．33e^-0.12A。建立了该环境条件下的钢筋混凝土锈蚀破坏模型，与已有单一因素影响下的同类模型相比，该模型对钢筋混凝土锈蚀破坏过程，特别是锈蚀诱导期，进行了更为详细的描述：诱导期应分为两个阶段，第一阶段为诱导发展期，主要由杂散电流诱发钢筋锈蚀；第二阶段为诱导加速期，该阶段主要由氯离子诱发钢筋锈蚀。深入研究了杂散电流对水泥石内部固化态氯离子稳定性的影响规律，研究结果表明杂散电流会对水泥石固化氯离子的能力产生不利影响，随杂散电流强度增加和通电时间延长，氯离子由固化态向游离态的转变趋势越为显著。采用C₃A和C-S-H凝胶制备等宏观试验方法，以及X射线衍射（XRD）、热重分析（TG）、表面电位等微观测试手段探明了杂散电流对固化态氯离子稳定性的不利影响，主要与以物理吸附形式固化的氯离子稳定性有关。同时采用Stern凝胶双电层理论对这种影响机理进行了详细的论述与分析。此外，根据杂散电流影响下氯离子由固化态向游离态的转变规律，提出了水泥石内部化学键合和物理吸附两种固化态氯离子的分离方法。系统研究了杂散电流对氯离子向混凝土内部迁移过程的影响规律，探明了氯离子在杂散电流影响下会加速向钢筋表面区域汇聚的迁移特征。通过分析杂散电流在混凝土内部所形成电场的分布特点，根据电渗流理论和X射线能谱（EDXA）等微观测试分析结果，提出了“扩散电迁移”假说对杂散电流影响下的氯离子迁移机制进行解释。同时在考虑杂散电流对混凝土固化氯离子能力和氯离子分布影响的基础上，建立了杂散电流存在情况下氯离子向混凝土内部的迁移方程。根据杂散电流与氯离子共存环境下钢筋混凝土的劣化特征和劣化机理，提出了该环境条件下地铁工程混凝土材料：56d电阻率>100kΩ·cm，28d电通量≤350C，氯离子扩散系数0．5-0．8×10^-13m²／s的高阻抗、高抗渗的设计要求与设计方法。从材料学角度出发，采用材料复合制备原理，利用矿物掺合料、轻集料和绝缘型聚合物等功能材料复合使用的方法，成功的制备出了56d混凝土电阻率为110．5kΩ·cm，28d电通量为223C的能够满足地铁工程高阻抗和高抗渗要求的新型高性能混凝土。更多还原

【Abstract】 The concrete structure of subway project usually is in stray currents and chloride ion coexisted corrosion environment. Because of stray currents and chloride ion mutual promoter action on the concrete durability deterioration, the concrete durable problem of this kind of project is more serious, and its durable deteriorated mechanism is also more complex than the single factor function. In this thesis, the deteriorated characteristic and mechanism of reinforced concrete, as well as the corresponding high durable material preparation have been researched in system and depth. There are important theory and practice guiding meaning of the results of this research for the durable design and the application of the subway and so on the underground project concrete material.The main research work and compliments of this paper are:Through the systematic research on the electrochemical equivalent and the corrosion characteristic of the steel bar, as well as the corresponding physical mechanics performance degeneration characteristic of reinforced concrete under stray currents and chloride ion coexistent environment, the deteriorated characteristics of reinforced concrete, such as steel bar corrosion speed quick, the corrosion degree serious as well as the quick deteriorated characteristic of the concrete compressive strength and the elasticity ratio have been obtained. Simultaneously used the electrochemistry test technology, verified the change rule that the limiting concentration value of the chloride ion to initiate the steel bar corrosion was reduced with stray currents intensity increased, the attribute method of chloride to initiated the steel bar corrosion was proposed: [Cl^-]/[OH^-] = 2.33e^0.12A. The reinforced concrete corrosion destruction model had been established under this environmental condition, compared with the sole factor influence similar model, this new model to the reinforced concrete corrosion destruction process, specially rusts away the induction period, had carried on a more detailed description: the induction period should divide into two stages, the first stage is the induction period of expansion, mainly induces the steel bar corrosion by the stray current; The second stage is the induction acceleration period, this stage mainly induces the steel bar corrosion by the chloride ion.The influence rule of the stray current on the binding chloride ion stability has been researched in depth. The results show that stray currents are disadvantage for the cement motor binding chloride ion. The transition trend of chloride form binding to freedom is more obviously with the stray current intensity increased. Uses the single mineral preparation, the C-S-H gel preparation and the microscopic testing method such as X-ray Diffractometer （XRD）, thermogravimetric analysis （TG）, the superficial electric potential, to verifies the stray currents to the binding chloride ion stable adverse effect mainly related with the chloride ion stability which solidified by the physisorption form, the Stern gel electric double layer theory is used to carry on the detailed elaboration and the analysis to this kind of influence mechanism. In addition, according to the transition characteristic of chloride form binding to freedom with stray currents influence, a method for separated the binding and free chloride ion is found.The systematic research has carried about the effect of stray currents on the migration process of chloride ion into concrete. The migration characteristic that chloride ion is accelerated to the steel bar surface region gathering under the stray currents influence. By analyzed the distributed characteristic of the electric field of stray currents in the concrete interior, and according to the electricity transfusion theory and Energy Dispersive X-ray Analysis （EDXA） and so on the microscopic test analysis result, proposed "the diffuse and electromigration" hypothesis to the explanation to migration mechanism of chloride ion in concrete interior under the stray currents influence. Based on the influence of stray currents on binding stability and distribution of chloride ion, the chloride ion to the concrete internal transport equation has been established.According to the reinforced concrete deteriorated characteristic and mechanism under the stray current and chloride ion coexisted corrosion environment, the design method and requirements for concrete are proposed: 56 days electrical resistivity≥100 kΩ·cm, 28 days flux≤350C, and chloride ion diffused coefficient between 0.5×10^-13m²/s and 0.8×10^-13m²/s .Embarks from the material study angle, according to the material compound preparation principle, a new kind high performance concrete was prepared, which is able to fit for the requirement of high electrical resistivity and anti-chloride ion permeability for subway concrete by compound uses mineral admixtures, lightweight aggregate and insulation polymer. Its 56 days electrical resistivity is 110.5 kΩ·cm, 28 days flux is 350 C.更多还原