Half-Cell Potential Measurement as a Non-destructive Evaluation of Chloride Diffusion Coefficient

Since it can negatively impact the intended service life, corrosion of embedded reinforcement in concrete is regarded as a severe durability risk for any reinforced concrete (RC) structures. Corrosion-induced early deterioration of RC structures eventually necessitates expensive repairs to get them back to serviceable conditions. Presence of chloride ion accelerates the corrosion process by removing the passivation layer of embedded steel making it a serious concern in the coastal regions. For rapid remedial action to be taken, early detection of an RC structure's propensity for corrosion is crucial. It is therefore important to monitor the extent to which chloride has permeated into the structure. Determination of chloride diffusion coefficient (Drcm) by Rapid Migration Test (RMT) is a reliable method for evaluating the degree of chloride penetration susceptibility of an RC element which is a destructive and time-consuming method. The Drcm values are widely used for evaluating the remaining service life of RC structures affected by chloride induced corrosion. Alternatively, half-cell potential (HCP) measurement is widely considered as a dependable non-destructive method to estimate the corrosion potential of RC structures and can be used to both assess corrosion resilience and identify corrosion likelihood. In this study, 36 unique mixes with varying proportions of supplementary cementitious material (0–40% replacement level of Ordinary Portland cement by fly ash or slag) and having different design strengths and slump values were submerged in 5% NaCl solution for 730 days (2 years). The corrosion potential and Drcm of these mixes were observed and correlated. The outcome of the study provides scope for further research into developing a model for directly correlating the corrosion potential to Drcm for predicting the service lives of RC structures under saline environment.