Session: RIP: Predictive Modeling and Characterization of Corrosion Processes in Complex Environments (In Honor of Professor Digby Macdonald) (Part I of IV)
Extrinsic vs Intrinsic Factors in Critical Chloride Threshold for Forecasting Corrosion of Steel in Concrete (RIP2026-00102)
The critical chloride threshold (CT) is a key component in most quantitative forecasting models for corrosion of steel in concrete. However, the very concept of a threshold has come under increasing scrutiny, in part because of the large variability of recorded CT values in seemingly comparable conditions. On the other hand, some of that variability may be reduced by consideration of often ignored factors such as the value of the steel potential while still in the passive condition. Recent work by D. Macdonald and collaborators addressed that dependence with a theoretical explanation focusing on the properties of the passive film - calling it here an intrinsic factor. This investigation in progress builds on those findings while considering extrinsic factors prevalent in concrete, such as the added effect of environmental composition changes that are induced in the passive zone by prior corrosion activity in nearby regions or other polarization sources.
