Effects of Mill Scale and Steel Type on Passivation and Accelerated Corrosion Behavior of Reinforcing Steels in Concrete

The influence of mill scale and steel type on the passivation capability and impressed current-induced accelerated corrosion behavior of reinforcing steels in concrete was studied using electrochemical impedance spectroscopy (EIS) and backscattered electron (BSE) images. Conventional low-carbon (LC) reinforcing steel and Cr-bearing low-alloy (LA) reinforcing steel with and without mill scale were prepared. After natural passivation and accelerated corrosion, it was confirmed that the initial passivation capability of steels and the corrosion-induced concrete cracking were significantly affected by the mill scale on steel surface. Also, the steel type played an important role on the characteristics of the corrosion layers as well as the long-term passivation capability. Furthermore, the corrosion pattern of steels induced by this accelerated corrosion was compared with that after long-term natural exposure to chloride solution.