Corrosion of Rebar in Concrete. Part I: Calculation of the Corrosion Potential in the Passive State

Abstract Knowledge of the corrosion potential (ECP) in the passive condition is important in assessing corrosion in reinforced concrete structures. While ECP is routinely measured, great scatter is reported, because the ECP is a sensitive function of many variables (T, [O2], pH, [Cl-], and the poorly defined mass transfer conditions). In this paper, a Mixed Potential Model (MPM) is used to calculate the ECP. The ECP shifts sharply in the negative direction when the passive current exceeds the limiting current density for oxygen transport to the steel surface. This shift is frequently misinterpreted as indicating passivity breakdown of the steel only.