Corrosion Improvement of Carbon Steel in Concrete Environment through Modification of Steel Microstructure

Abstract

This study investigated the impact of the grain size of low carbon steel on its electrochemical behavior in a simulated concrete pore solution. Specimens with three grain sizes were used: as-received; coarse, with grains approximately 2 times larger than those in the as-received steel; and fine, with grains approximately half the size of those in as-received specimens. Specimens were immersed in a chloride-free pore solution for 10 days and then 3% by weight NaCl was added to the solution. The specimens were then kept in the chloride-contaminated solution for 60 days. The corrosion behavior of the specimens was evaluated by different electrochemical measurement techniques. Results showed that fine specimens passivated first, followed by the coarse and as-received specimens. However, in chloride-contaminated pore solution, the as-received specimens corroded more, followed by the fine and coarse specimens. In fact, the coarse specimens remained passive after 60 days of exposure to the chloride-contaminated pore solution.