Analytical modelling of chloride diffusion in circular section concrete columns with binding effects

Abstract

– Reinforced concrete structures in marine environments face significant durability challenges due to chloride-induced corrosion of the steel reinforcement. Understanding and modelling chloride ingress are critical for the prediction of the service life of these structures. This study presents an analytical model for chloride diffusion in circular section concrete columns, addressing a critical gap in existing research by incorporating the effects of chloride binding. The model employs a bilinear chloride binding isotherm to derive an analytical solution in cylindrical coordinates, which captures the nonlinear interaction between free and bound chlorides. Validation is performed by comparing the model's predictions with numerical and experimental solutions from one-dimensional cylindrical and slab coordinate systems, demonstrating high accuracy. The results show that the diffusion front advances more rapidly in the cylindrical model than in the slab model. For instance, chloride ingress reaches approximately 90 mm in a circular section column after 10-year diffusion time, whereas in a corresponding concrete slab, it extends only to about 80 mm. The present model offers engineers a valuable tool for designing and maintaining durable reinforced concrete columns in chloride-rich environments, contributing to enhanced service life predictions and more resilient infrastructure.