Effect of Silicon Addition on Electrochemical Corrosion Resistance of Carbon Steel in Concrete Pore Solution

The effects of Si content on the corrosion behavior and passivation of carbon steel bars in concrete pore solution were studied analytically, and its enhanced corrosion resistance was considered. Electrochemical impedance spectroscopy analysis and polarization techniques were used to investigate the electrochemical corrosion behavior of the samples. The lower mass-loss rate for the steel bar with 0.57 wt% Si content in the initial corrosion indicated an improvement of the corrosion resistance in the carbon steel matrix before the creation of a dense rust layer on the sample surface. The polarization plots exhibited that the steel bar with 0.57% Si content had minimum corrosion-current density compared to the other specimens which were in passive state during the experiment. The electrochemical results show that micro-alloying of Si element in the carbon steel bar matrix improved its corrosion resistance against chloride ion attack and delayed the corrosion initiation into the steel matrix. FESEM images of the specimens indicated that the surface of the carbon steel bar with 0.57% Si was smooth and no noticeable corrosion was found.