Morphology of corrosion products of steel in concrete under macro-cell and self-corrosion conditions

In this paper investigations into the formation of specific corrosion products during the process of chloride induced corrosion of steel in concrete are presented. The extension of corrosion products within concrete was established by means of X-ray tomography analyses. Then a detailed analysis of the nature of corrosion products has been conducted by means of Raman micro-spectroscopy and energy dispersive spectroscopy. Results emphasize two different corrosion patterns. The first one is composed of shallow cavities, where mostly magnetite and goethite were identified, traducing aerated to moderate aerated conditions in these media. The second pattern was identified as deep, needle-like pits, where chlorinated-iron-oxides phases were present associated with more or less important chloride enrichments. The presence of these particular species is indicating low redox and low pH conditions within these pits.