A Methodology for Projecting Time-to-Corrosion Initiation and Cracking/ Delamination for Reinforced Concrete with an Admixed Corrosion Inhibitor

摘要

An equation from the literature was modified such that the cumulative distribution function (CDF) of CI~- concentration in concrete at the reinforcement depth after a given exposure time was calculated by numerical integration. The approach accommodated the fact that surface CI" concentration (C_s), the effective diffusion coefficient (D), and cover (x) are distributed rather than discreet variables. Calculations were performed for a range of mean D, C_(sa) and x values. Limiting concentrations of CI" for which various previously reported dosages of the corrosion inhibitor calcium nitrite (CN) are effective in maintaining reinforcing steel passivity were superimposed upon the CDFs. This allowed projection of the percentage of reinforced elements that are active after a specific time and, hence, inhibitor effectiveness, to be identified. Also discussed are scenarios and implications thereof for chlorides and CN being solely in the cement phase as opposed to being uniformly distributed throughout the concrete.