Impact of a concrete coating on the reinforcement corrosion in cracked concrete

Impact of a concrete coating on the reinforcement corrosion in cracked concrete. Cracks in reinforced concrete structures exposed to chlorides can significantly impair the durability. Cracks are a fast pathway for chlorides and corrosion initiation of the reinforcement is more likely. Relevant standards [[]1, 2] require additional measures to prevent chloride ingress into structures exposed to chlorides such as parking decks. Additional design principles to ensure the durability of parking decks are given by the German Society for Concrete and Construction Technology (DBV) [[]3]. One principle consists of the application of a crack bridging concrete coating to prevent further chloride and moisture supply once early cracking is completed even though chlorides are already present in the crack. This recommendation is in line with the repair principle W-Cl according to RL SIB [[]4] and the procedure 8.3 DIN EN 1504-9 [[]5] respectively with the objective to increase the concrete resistivity. In an extensive experimental study it can be shown that concrete coating prevents corrosion and can even stop macro cell corrosion successfully in bending cracks with short-term chloride exposure. The repassivation is based on the increase of the anodic polarization resistance due to oxide layer formation and/or limited supply of chlorides. The concrete resistivity increases as well because of ongoing drying of the concrete but its effect on the macro-cell activity is negligible. It remains to be determined which amount of chlorides can be left in the concrete to exclude on-going reinforcement corrosion reliably.