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Design of a cementitious coating system for corrosion protection: Phase 1 binder materials selection
(2014)
This paper presents the first results of an ongoing research project on the development of a cementitious thin layer coating system with high resistance against chloride penetration and carbonation. It is intended to display the decision process used for selecting raw materials as well as the conclusions based on test results and theoretical deliberations. In this phase, only the influence of the binder materials was analyzed concerning mechanical properties. The system should enhance the durability of new and old concrete structures exposed to aggressive environments, be based on market available materials and fulfill the requirements of the German guideline for concrete repair (Rili-SIB).
Concrete-glass windows or commonly referred to as “Dalle de Verre” windows are prevalent in historical monuments across Europe. “Dalle de Verre” windows were made by placing cut stained glasses, of various shapes and sizes, into a steel reinforced concrete frame. In addition to the steel reinforcement, a few steel wires run across the concrete elements to hold the glass windows into place. Much of these structures have been damaged due to carbonation of the thin concrete covers and consequent corrosion of the steel reinforcement; and exhibit several cracks due to the expansive nature of corrosion products formed at the steel–concrete interface. This study focussed on understanding the efficacy of electrochemical realkalisation in reinstating the passive state of the steel reinforcement embedded in such concrete glass windows. Simulant “Dalle de Verre” windows (representative of windows at Kaiser-Wilhelm Gedächtniskirche) were produced using different cements with a water/cement ratio of 0.6 and carbonated under accelerated conditions. Post carbonation, the concrete glass windows were electrochemically realkalised using a sacrificial anode. The influence of highly alkaline conditions due to electrochemical realkalisation on the glass-concrete interface has also been investigated. This study shows that the passive state of the steel reinforcement in “Dalle de Verre” windows, particularly at the Kaiser-Wilhelm Gedächtniskirche (memorial church) in Berlin, can be reinstated using the electrochemical realkalisation method.