Analytical Evaluation of Time-to-Corrosion for Chloride-Exposed Reinforced Concrete with an Admixed Corrosion Inhibitor: Part 1—No Inhibitor Egress

Abstract

A first-principles-based equation from the literature was modified such that the cumulative distribution function (CDF) of Cl− concentration ([Cl−]) in concrete at the reinforcement depth after a given exposure time was calculated by numerical integration. The approach accommodates the fact that surface Cl− concentration (Cs), the effective diffusion coefficient (D), and reinforcement cover (x) each conform to a distribution, rather than being discreet. Calculations were performed for a range of mean D, Cs, and x values. The previously reported limiting [Cl−] for which various dosages of the corrosion inhibitor calcium nitrite (CN) are effective in maintaining reinforcing steel passivity was superimposed upon the CDF. From probability distributions of, first, [Cl−] and, second, Cl− threshold to initiate active corrosion, as enhanced by a particular CN addition, the percentage of reinforced concrete elements for which active corrosion initiates after specific times and, hence, inhibitor effectiveness, were...