Stability of Fe2+ in cementitious media

Abstract

Service-life models developed for reinforced concrete structures have worked under the assumption that once corrosion initiates, the precipitation of corrosion products occurs predominantly at the steel-concrete interface (SCI) generating expansive stresses, subsequently leading to the spalling of the concrete cover. Recent work has explicitly shown that corrosion products could also precipitate a few hundred microns away from the SCI. The development of corrosion products further away from the SCI has been hypothesised to be due to competition between the kinetics of diffusion, precipitation/sorption and oxidation of aqueous Fe2+, once dissolved due to corrosion. This study experimentally assesses the stability of Fe2+ in solutions representative of conditions where the steel reinforcement is undergoing carbonation- induced corrosion. We use spectrophotometric techniques to quantify the kinetics of iron oxidation in solutions with pH ranging between 5 and 9. This data would feed into a reactive transport model enabling us to develop a better understanding of the propagation phase of corrosion in reinforced concrete structures.