Most damage prediction models for reinforcing steel in concrete treat the corrosion initiation stage as being nearly independent of the propagation stage elsewhere in the system. A next-generation chloride-induced corrosion interdependent model addresses those interactions by incorporating the corrosion prevention effect of the local potential drop caused by prior active-to-passive transitions in nearby steel portions. The effect of this potential-dependent threshold (PDT) approach was examined in a 3D realization, confirming and expanding conclusions from previous 1D and 2D models. Exploratory analysis was conducted for model result sensitivity to time step duration and activation zone size. It was found that the main outcome—a strongly lowered long-term damage projection when PDT is taken into consideration was reasonably robust to changes in those variables. The precise damage amount forecast was however sensitive to an extent that needs more detailed analysis. Sensitivity to time step choice appears to be resolvable in the limit, but the selection of appropriate activation zone size needs addressing in future work.

Useful corrosion damage forecast and risk evaluation methods for steel in concrete were developed starting about three decades ago and are now being used by increasing numbers of engineers. Much room for improvement remains, however, and the following non-exhaustive selection of issues merit special attention in the next generation of predictive models: incorporation of chloride binding in predicting chloride ion penetration to avoid overly conservative design, resolution by additional mechanistic understanding, and a wider database of uncertainty in the long-term evolution of chloride diffusivity in aged concrete, consideration of geometric chloride transport obstructions at the rebar level, and integration of initiation and propagation stage modeling, in particular accounting for the dependence of the chloride threshold on steel potential. Each feature is discussed with attention to the conservative or non-conservative result of its eventual incorporation, and with indication of practical means for its implementation.