Predicting the time to corrosion initiation in reinforced concrete structures exposed to chlorides

Abstract

Reliable predictions of the time to onset of corrosion in reinforced concrete are essential for service life modelling, to ensure sufficient durability, and for holistic sustainability assessments of new materials. All existing models are based on the same concept, that is, predicting the development over time of the chloride content at the level of the steel and comparing this numerical result with the critical chloride content for corrosion initiation, Ccrit. This paper presents example calculations utilizing input data derived from both laboratory specimens and from structures, illustrating the poor predictive power of state-of-the-art models. While it is generally assumed that improving chloride ingress models will improve the prediction of the time-to-corrosion, this paper shows that the bottle neck to more reliable predictions are rather i) the lack of fundamental understanding of corrosion initiation, ii) the use of non-representative laboratory results, and iii) ignoring the size-effect in localized corrosion.