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，对社会保持流动性和确保房地产库存至关重要。钢筋混凝土上的氯离子效应在这里起着核心作用。修复氯化物造成的损害会造成相当大的经济损失。在W-Cl修复概念中，混凝土结构(例如停车场甲板或地下停车场底板)的表面涂有一层涂层，可防止进一步的氯化物和水渗透，但允许组件干燥。由于混凝土的脱水，腐蚀过程的速度大大降低，因此进一步的破坏过程充其量是停滞不前的。根据W-Cl原理修复受氯污染的部件比通常使用传统的修复方法更具成本效益。作为DFG研究项目的一部分，现已对其应用范围进行了基础研究。该研究项目于2019年成功完成，并在评估中获得广泛认可，该项目表明，保证修复成功的边界条件具有高度的限制作用：螺纹钢或水蒸气扩散抑制涂层的高氯含量抑制了腐蚀率不会降低到无害的水平。因此，这一修复原则在未来的应用范围也非常有限。为了扩大这些维修程序的适用范围，将在后续项目的框架内进行进一步调查，并审查新的解决办法。为此，将进一步检查涂层系统，并进一步检查最初研究项目的测试样本。对于含氯量高的RC组分，一种新的溶液方法是对被氯污染的和最初未涂覆的组件进行定向干燥(例如通过热处理)。为此目的，须根据实际测试样本，提供在地下停车场以室外储存方式进行维修的长期成功证明。最后，对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将被用来澄清DFG先前研究项目中获得的结果。具体地说，要确定极限值，根据极限值可以假定无害的“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.