Quantitative Study on MCI Rehabilitating Steel Bars in Chloride-Contaminated Concrete Based on Inhibition and Transport Behaviors

摘要

The transport and inhibition behaviors of a migrating corrosion inhibitor (MCI, marked PCI-2015) in reinforced concrete (in this paper, only mortar specimens were used for testing) contained different contents of NaCl (0.25, 0.5, 0.75, and 1% by weight of cement) with three water-cement ratios (0.45, 0.55, and 0.65) were investigated by using absorption tests and electrochemical measurements. The results indicated that the measured absorption weight of PCI-2015 basically agrees with the numerical value calculated by the modified MCI transport model, and the representative absorbed weight of PCI-2015 in W/C 0.65 concrete with 1% NaCl was 16.23 g/kg at 1 day, while the corrosion current (I_(corr)) of steel bars in the concrete was reduced to 0.02 μA/cm~2 from the initial data 1.38 μA/cm~2. The visual observation of surface condition for steel bars in concrete mixed with 1 % NaCl by broken specimens showed that the surfaces of steel bars in concrete treated with PCI-2015 were bright. X-ray photoelectron spectroscopy (XPS) analysis of steel bar removed from concrete specimens demonstrated the chloride ion on the steel surface was replaced by atoms or molecules of the inhibitor. By using multivariate nonlinear regression analysis, the relationship among the corrosion current density (I_(corr)) of steel bar in concrete, water-soluble chloride contents (C_(Cl)), and the calculated mass concentration of PCI-2015 at steel-concrete interfacial zone (C_(in)) were established. So a quantitative assessment method for MCI repairing steel bars in chloride contaminated concrete based on MCI inhibition and transport performance was suggested.