Influence of Crack Width and Supplementary Cementitious Materials on Chloride-Induced Corrosion of Reinforcement in Concrete

Abstract

Steel reinforcement corrosion is one of the major problems that jeopardise the durability of reinforced concrete structures, especially in marine and de-icing salt environments, where chloride-induced corrosion is one of the main mechanisms affecting the durability. The surface cracks create pathways for chloride ingress, while supplementary cementitious materials (SCMs) introduce to the concrete to refine the pore structure and reduce chloride diffusivity to improve the durability of concrete. The relationship between the combined effect of crack width and various SCMs and the corrosion of reinforcement has yet to be fully studied under a common numerical simulation framework, however. The approach used in this study is based on the simulation in order to test the influence of the crack width and incorporation of SCM on chloride-induced corrosion of reinforced concrete. Simulations of chloride transport were performed using a Finite Difference Method (FDM) in MATLAB, the corrosion initiation time was predicted, and the long-term corrosion deterioration of the reinforcement was assessed for different crack widths and different degrees of SCM replacement. The proposed framework considers five criteria for durability: chloride concentration on the reinforcement level, chloride penetration depth, time to corrosion initiation, mass loss of the reinforcement and depth of corrosion penetration. The simulation results show that the wider the crack, the shorter the time for the chloride to penetrate the crack and the shorter the time for the commencement of corrosion, which will also cause more deterioration of reinforcements; and that the incorporation of SCM effectively reduces chloride transport and delays the onset of corrosion. Metakaolin and silica fume showed the highest resistance to chloride induced corrosion among the investigated supplementary cementitious materials followed by GGBS and fly ash, which are superior compared to conventional concrete. The proposed simulation framework is an effective method for simulating long-term durability of reinforced concrete and can be useful for selecting appropriate SCM and crack-control methods to ensure the durability and service life of reinforced concrete structures. The proposed MATLAB-based finite difference simulation framework provides an efficient computational approach for predicting chloride-induced corrosion and evaluating the influence of crack width and supplementary cementitious materials on the long-term durability of reinforced concrete structures.