Modelling two-dimensional chloride diffusion in repaired RC structures for sustainable maintenance management

Both public and private infrastructure management agencies are responsible for chloride-related corrosion damage to coastal reinforced concrete (RC) structures, which often requires extensive repairs. These repairs are intended to provide serviceability and safety while reducing costs and environmental impact. While there are many repair methods, techniques, and materials available, little is known about their long-term performance and durability. This study examines two-dimensional chloride ingress into square cross section RC columns and their durability using cover replacement techniques with several shapes, thicknesses, locations, and repair times. First, a two-dimensional repair model is developed to simulate these repair strategies and predict their serviceability performance. Two orthogonal concrete replacement strategies (OCR1 and OCR2) and one circular concrete replacement strategy (CCR3) are studied. Next, a method to evaluate and compare maintenance strategies in terms of durability, cost, and environmental impact is also considered. The results of this study reveal that the corners of a column are the most critical areas to evaluate chloride concentration when predicting the time of corrosion initiation and estimating repair time. For long-term maintenance management, the circular concrete replacement strategy is recommended over orthogonal concrete replacement for repair of RC columns exposed to chloride-induced corrosion. The CCR3 strategy requires fewer repairs and achieves higher cost-effectiveness and sustainability compared to the other strategies.