Critical Conditions for Depassivation of Steel in Concrete: Interface Chloride Profiles and Steel Surface Condition

Magazine article, 2012

The composition and macrostructure of the concrete-steel interface and the surface finish of the steel are fundamental for the chloride induced corrosion initiation in reinforced concrete, with direct influence in the chloride threshold values (Cth). In this paper these characteristics were examined for vertically cast samples immersed in salt solution. After depassivation, the specimens were open for visual examination. Corrosion always initiated at the front side and surface defects were found to influence the corrosion onset. Chloride, calcium and iron profiles along the interface were drawn by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and higher chloride contents were measured around active corroding areas.