钢筋混凝土结构强制电流阴极腐蚀控制系统

发布时间：2018-10-31 20:24

【摘要】：钢筋腐蚀是降低钢筋混凝土结构耐久性的主要原因，，阴极保护（Cathodic Protection,CP）是迄今能够直接阻止钢混结构腐蚀的唯一有效途径。确保强制电流阴极保护（Impressed Current Cathodic Protection，ICCP）系统精确可靠的核心问题在于高效耐久阳极材料的研制和ICCP系统电场投放精确的模拟。本文采用理论研究、数值模拟与试验验证相结合，制备了多尺度碳/水泥复合阳极材料，并对ICCP的电场投放进行了系统研究。首先，分析了单掺碳纤维、纳米碳黑、碳纳米管水泥复合材料的导电性能，根据其导电机理，结合经济性和可施工性，进而制备了多尺度碳/水泥复合阳极材料。通过加速极化试验对多尺度碳/水泥复合阳极材料的抗极化性进行研究，并采用SEM、EDS等对阳极材料的极化机理进行了分析。结果表明，阳极材料的极化过程包括三个阶段，前两个阶段分别由于水泥基体含水率的升高、阳极材料内部反电场的形成致使阳极材料的极化电位缓慢上升，第三阶段则由于碳纤维被氧化导致试件极化电位骤升，前两个阶段的稳定期为阳极材料的有效服役期。此外，在极化过程中多尺度碳/水泥复合阳极材料对侵蚀离子Cl-具有抗干扰性。结合极化性能，确定多尺度碳/水泥复合阳极材料的理想配比为CF03CNT15CB2，该掺量的阳极材料在1200mA/m2极化电流和PH值为13.5的极端环境下，其稳定期可达200h以上。其次，通过对ICCP系统投放电场Laplace方程和COMSOL的腐蚀模块二次电流接口原理的分析，建立了ICCP系统电场投放的COMSOL数值模拟方法。将实测的阳极极化曲线和复杂腐蚀状态下的阴极极化曲线加载在电极反应界面，采用自由四面体剖分网格，利用COMSOL稳态求解器，建立了ICCP电场投放的数值计算模型。运用COMSOL后处理程序，对钢筋表面电位和电流密度、混凝土的电场分布进行了分析。结果表明，临近阴阳极的混凝土区域的电场最强，而钢混界面的电流密度最大。ICCP系统通过临近钢筋表面局部区域所铺设阳极材料实现对钢筋的有效保护。最后，根据所建立的ICCP腐蚀控制系统电场投放的COMSOL数值模型，结合所制备多尺度碳/水泥复合阳极材料，搭建了T型梁和空心圆柱ICCP腐蚀控制原型系统，并对钢筋表面电位进行了数值模拟和试验结果对比。结果表明除了T型梁上个别测点外相对误差均在20%以内，试验验证了ICCP腐蚀控制系统COMSOL数值模型的可靠性。此外，根据欧美阴极保护标准中的保护电位准则和100mV极化衰减准则，通过测量钢筋表面的半电池电位和20h的极化衰减值，对所搭建的ICCP系统钢筋腐效果进行了评价。结果表明，通过ICCP腐蚀控制电场投放的优化设计，可实现对T型梁和空心圆柱等典型构件腐蚀的合理保护,所制备的多尺度碳/水泥复合阳极材料可用于工程实践。
[Abstract]:The corrosion of steel bar is the main reason to reduce the durability of reinforced concrete structure. Cathodic protection (Cathodic Protection,CP) is the only effective way to directly prevent the corrosion of steel concrete structure. The key to ensure the accuracy and reliability of (Impressed Current Cathodic Protection,ICCP) system lies in the development of high efficiency durable anode material and the accurate simulation of electric field in ICCP system. In this paper, multi-scale carbon / cement composite anode materials were prepared by theoretical study, numerical simulation and experimental verification, and the electric field of ICCP was systematically studied. Firstly, the conductive properties of carbon fiber, carbon black and carbon nanotube cement composites were analyzed. According to its conductive mechanism, the multi-scale carbon / cement composite anode materials were prepared according to its conductive mechanism, economy and constructability. The polarization resistance of multi-scale carbon / cement composite anode materials was studied by accelerated polarization test, and the polarization mechanism of the anode materials was analyzed by SEM,EDS et al. The results show that the polarization process of the anode material consists of three stages. The polarization potential of the anode material increases slowly in the first two stages due to the increase of the moisture content of the cement matrix and the formation of the antielectric field inside the anode material. In the third stage, the polarization potential of the sample increases sharply due to the oxidation of carbon fiber, and the stable period of the first two stages is the effective service period of the anode material. In addition, the multi-scale carbon / cement composite anode material has anti-interference to the erosion ion Cl- in the process of polarization. Combined with polarization properties, the optimal ratio of multi-scale carbon / cement composite anode material is determined to be CF03CNT15CB2,. The stable period of anode material with CF03CNT15CB2, content is over 200h under the extreme environment of 1200mA/m2 polarization current and PH value of 13.5. Secondly, by analyzing the Laplace equation of electric field in ICCP system and the principle of secondary current interface of COMSOL corrosion module, the COMSOL numerical simulation method of electric field in ICCP system is established. The measured anodic polarization curve and the cathodic polarization curve under complex corrosion state were loaded at the electrode reaction interface. The numerical calculation model of ICCP electric field was established by using the free tetrahedron mesh and the COMSOL steady-state solver. The surface potential, current density and electric field distribution of concrete were analyzed by COMSOL program. The results show that the electric field of concrete near the cathode and anode is the strongest, while the current density of the steel / concrete interface is the largest. The ICCP system can effectively protect the steel bar by using the anode material laid near the local area of the steel bar surface. Finally, according to the established COMSOL numerical model of ICCP corrosion control system, combined with the multi-scale carbon / cement composite anode material, the prototype system of T-beam and hollow cylindrical ICCP corrosion control system is built. The surface potential of steel bar is simulated and compared with the test results. The results show that the relative error is less than 20% except for some measuring points on T-beam. The reliability of COMSOL numerical model of ICCP corrosion control system is verified by experiments. In addition, according to the protection potential criterion and 100mV polarization attenuation criterion in the European and American cathodic protection standards, the corrosion effect of the steel bar in the ICCP system was evaluated by measuring the half-cell potential on the steel bar surface and the polarization attenuation value for 20 hours. The results show that the optimum design of ICCP corrosion control electric field can protect the corrosion of typical components such as T-beam and hollow cylinder reasonably, and the multi-scale carbon / cement composite anode material can be used in engineering practice.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375

【相似文献】