长期阴极保护系统中高稳定性外部阳极砂浆的基础研究

Impressed current cathodic protection is considered as an efficient method for corrosion protection of reinforced concrete; however, there are some limitations and drawbacks for this technique, i.e. acid erosion of the external anode mortar, un-uniform distribution of the protection current. In this project, the conductive porous lightweight aggregates (loaded with conductive components) and self-healing microcapsule materials (encapsulated with alkaline substances) will be prepared. When the conductive porous lightweight aggregates and self-healing microcapsule materials are applied in the external anode mortar, on one hand, the conductivity of the mortar, anode/mortar interface and mortar/concrete interface can be increased, leading to a more uniform distribution of the protection current; on the other hand, the alkalinity of the external anode mortar can be restored and the erosion effect on the external anode mortar caused by the acidification of pore solution is halted. Therefore, the external anode mortar of superior stability prepared with the conductive porous lightweight aggregates and self-healing microcapsule materials can improve the protection efficiency stability of impressed current cathodic protection and durability of reinforced concrete. The investigations in this project include the design and preparation of the conductive porous lightweight aggregates and self-healing microcapsule materials, and their effect on the conductivity uniformity and acid erosion resistance of the external anode mortar. Therefore, the preparation principles and methods of the conductive porous lightweight aggregates and self-healing microcapsule materials, and the mechanisms related to the effect of the prepared external anode mortar of superior stability on the protection efficiency stability of impressed current cathodic protection will be revealed in order to provide the theoretical basis of a new highly efficient corrosion protection and repair method for reinforced concrete.

外加电流阴极保护技术是钢筋混凝土腐蚀防护的有效手段，但是存在外部阳极砂浆易受酸化侵蚀、保护电流分布不均匀等弊端。本项目拟制备负载导电组分的导电多孔轻骨料和包裹碱性物质的微胶囊自修复材料。导电多孔轻骨料和微胶囊自修复材料应用于外部阳极砂浆中，一方面可以提高砂浆以及金属阳极/砂浆和砂浆/混凝土界面的导电性，改善保护电流分布；另一方面可以恢复外部阳极砂浆的碱度，抑制孔溶液酸化对外部阳极砂浆的侵蚀作用。由此开发的高稳定性外部阳极砂浆可以提高外加电流阴极保护效率的稳定性和钢筋混凝土的耐久性。课题将围绕导电多孔轻骨料和微胶囊自修复材料的设计和制备，及其对外部阳极砂浆导电均匀性和抗酸化侵蚀性能的影响等方面展开研究，揭示导电多孔轻骨料和微胶囊自修复材料的制备原理与方法，及其由此制备的高稳定性外部阳极砂浆提高外加电流阴极保护效率稳定性的作用机制，为研发更高效的钢筋混凝土腐蚀防护与修复新技术提供科学理论依据。

外加电流阴极保护技术是海洋环境中钢筋混凝土腐蚀防护的最有效手段。但是，该技术存在外部阳极砂浆易受酸化侵蚀、保护电流分布不均匀等弊端。本课题针对上述问题，制备了负载导电组分的导电功能性轻骨料和包裹碱性物质的微胶囊自修复材料，并将其应用于高性能外部阳极砂浆的制备；在此基础上，研究了导电功能性轻骨料和微胶囊自修复材料提高外部阳极砂浆导电均匀性和抑制酸化侵蚀破坏的作用机理。本课题在以下几个方面取得了创新性成果：.（1）设计制备了包裹修复组分的微胶囊自修复材料。微胶囊自修复材料中修复组分的释放具有很强的pH敏感性：当pH=13时，修复组分可以稳定的包裹在微胶囊自修复材料内；当pH≤11时，修复组分可以有效快速释放。.（2）设计制备了负载改性琼脂凝胶的导电功能性轻骨料。制备的导电功能性轻骨料一方面具有较好的导电性（电阻率为0.5 Ω∙m），另一方具有良好的碱性维持能力，可以维持混凝土孔溶液的高碱度。.（3）导电功能性轻骨料可以在外部阳极砂浆中形成有效的导电网络，因此可以有效的提高其导电性。导电功能性轻骨料与碳纤维复合后，可以进一步提高外部阳极砂浆的导电性，并降低砂浆中形成有效导电网络的碳纤维掺量。此外，导电功能性轻骨料还可以抑制酸化侵蚀破坏造成的外部阳极砂浆导电均匀性下降。.（4）由于负载的碱性组分可以有效释放，微胶囊自修复材料和导电功能性轻骨料一方面可以维持主阳极的高催化活性，提高主阳极电位的稳定性和服役寿命，另一方面对二次阳极砂浆中的酸化侵蚀破坏也能起到抑制作用。当外部阳极砂浆中碳纤维掺量为0.75 vol.%，导电功能性轻骨料掺量为40 vol.%时，其劣化速率降低了40 %。.（5）在外加电流阴极保护中，导电功能性轻骨料可以维持主阳极的高催化活性。此外导电功能轻骨料可以提高外加电流阴极保护运行过程中保护电流分布的均匀性。因此，本课题制备的高性能外部阳极砂浆可以有效地提高外加电流阴极保护的稳定性和保护效率，进一步提高钢筋混凝土的耐久性。