Influence of pre-rusting on steel corrosion in concrete
By Park, Zin-Taek; Choi, Yoon-Seok; Kim, Jung-Gu & Chung, Lan
Published in Cement and Concrete Research
2001
Abstract
Steel specimens in three different superficial states (machined, scaled, and pre-rusted) were embedded in concrete blocks (OPC) with various chloride contents (0.0, 0.4, and 2.5 wt.%/cement) and exposed to different levels of relative humidity (60–100%). Electrochemical methods for corrosion monitoring were applied for a period of 4 years. The concrete blocks were broken and mass changes of steel specimens were determined. The average corrosion rate of machined and scaled steel was lower than 1 μm/year in concrete with a low chloride content (≤0.4 wt.%). The pre-rusted steel in concrete even without any chloride content showed technically unacceptable average corrosion rate (>1 μm/year). For all steel specimens, corrosion was localized. The corrosion rate at these spots reached values up to 65 μm/year. Mass-loss data confirmed electrochemical results (polarization resistance), i.e. that the corrosion rate of pre-rusted steel reinforcement was unacceptable even in noncarbonated concrete without any chlorides present.