Time-to-Corrosion Initiation for Chloride Exposed Reinforced Concrete with an Admixed Corrosion Inhibitor: Part Ⅱ - Consideration of Diffusional Inhibitor Egress

摘要

A previous paper (Part Ⅰ) introduced a first-principles based equation whereby the cumulative distribution function (CDF) of chloride concentration ([Cl~-]) at the reinforcement depth (x) after a given time is determined considering that all relevant variables (effective diffusion coefficient, surface Cl~- concentration, and x) conform to a distribution rather than being distinct. Also considered were examples where the admixed corrosion inhibitor calcium nitrite (CN) was present. By superimposing the limiting [Cl~-] for CN effectiveness, as reported in the literature, upon the CDF([Cl~-]) trends, the percentage of reinforcement elements for which this [Cl~-] had been reached/exceeded was determined. Further, by employing a Load Resistance Factor Design type analysis, the percentage of elements for which corrosion initiation occurs was projected. In the present effort, the added consideration of diffusional inhibitor egress over time is taken into account; and the same determinations (percentage of elements for which, first, the critical [Cl~-] has been reached/exceeded and, second, active corrosion has initiated) were made. Comparisons are provided between the CN loss and no loss cases and the results discussed in terms of admixed corrosion inhibitor effectiveness.