Extension of the application limits of the W-Cl maintenance principle

确保钢筋混凝土构件的耐久性是一项技术要求很高的任务，对于社会保持流动性和确保真实的房地产存量至关重要。氯离子对钢筋混凝土的影响在这里起着核心作用。修复由氯化物造成的损坏会造成相当大的经济损失。在W-Cl修复概念中，混凝土结构的表面（例如停车场或地下停车场地板）提供有涂层，该涂层防止进一步的氯化物和水渗透，但允许部件干燥。由于混凝土的脱水，腐蚀过程的速度显著降低，因此进一步的损坏过程最好停止。根据W-Cl原理修理受氯化物污染的部件比通常的传统修理方法更具成本效益。作为DFG研究项目“关于修复原理W-Cl和确保耐久性的机制的基础研究“的一部分，现在已经进行了关于应用极限的基础研究。该研究项目于2019年成功完成，并在评估中获得了广泛的认可，表明确保修复成功的边界条件具有高度限制性的影响：钢筋或水蒸气扩散抑制涂层中的高氯化物含量抑制了腐蚀速率不会降低到无害水平。因此，这种修复原理在未来的应用范围也非常有限。为了扩大这些修复程序的应用范围，将在后续项目的框架内进行进一步调查，并审查新的解决方案。为此，将对进一步的涂层系统进行检查，并对初始研究项目的试样进行进一步检查。一种用于高氯化物含量RC部件的新型解决方案包括有针对性地干燥氯化物污染和最初未涂覆的部件（例如通过热处理）。为此，应根据实际测试样本，提供地下停车场外部储存维修长期成功的证明。最后，将使用WIPANO研究项目中非常干燥的混凝土情况下腐蚀电流测量装置测量结果的解释结果来澄清以前DFG研究项目中获得的结果。特别是，要确定极限值，从中可以假定无害的“被动电流密度”。

Ensuring the durability of reinforced concrete components is a technically demanding task and is of central importance for society to maintain mobility and secure the real estate stock. The chloride effect on reinforced concrete plays a central role here. The repair of the damage caused by chlorides causes considerable economic damage. In the W-Cl repair concept, the surface of the concrete structure (e.g. a parking deck or an underground car park floor plate) is provided with a coating that prevents the penetration of further chlorides and water, but allows the component to dry out. Due to the dehydration of the concrete, the velocity of the corrosion processes is significantly reduced, so that the further damage process comes to a standstill at best. Repairs of chloride-contaminated components according to the W-Cl principle are much more cost-effective than with the usually conventional repair methods. As part of a DFG research project "Fundamental studies on the mechanisms of repair principle W-Cl and to ensure durability ", basic studies on the limits of application have now been carried out. The research project, which was successfully completed in 2019 and received broad approval in the evaluation, shows that the boundary conditions that enable a guaranteed repair success have a highly restrictive effect: high chloride content at the rebar or water vapour diffusion-inhibiting coatings inhibit that corrosion rates are not reduced to a harmless level. Thus, the application limits of this repair principle are also very limited in the future. In order to extend the application limits of these repair procedures, further investigations are to be carried out within the framework of a follow-up project and new solutions are to be examined. For this purpose, further coating systems will be examined and the test specimens from the initial research project will be further examined. A novel solution approach for RC-components with high chloride contents consists in the targeted drying down of chloride-contaminated and initially uncoated components (e.g. by heat treatment). For this purpose, the proof of the long-term success of the repair by outside storage in an underground car park is to be provided on the basis of practical test specimens. Finally, the findings on the interpretation of measurement results of corrosion current measuring devices in the case of very dry concretes from the WIPANO research project will be used to clarify the results obtained from the previous DFG research project. In particular, limit values are to be determined from which a harmless "passive current density" can be assumed.