Role of mill scale on corrosion behavior of steel rebars in mortar

Abstract

The role of mill scale on the corrosion behavior of steel rebars in mortar was studied using Hyperbaric-Oxygen Accelerated Corrosion Tests (HOACT) and polarization measurements. Defects of mill scale deteriorated passivity of rebars when mortar and saturated Ca(OH)2 solution contained chloride. Localized corrosion beneath mill scale with defects was responsible for the acceleration of depassivation. SEM observations and Raman spectroscopy measurements revealed that a Fe3O4 layer initially formed under the mill scale and further corrosion resulted in migration of Fe ions through the defects and formation of a rust layer mainly composed of α- and γ-FeOOH on the mill scale.