Investigation of the Synergistic Effect of Sodium Nitrite and Sodium-Potassium Tartrate for Corrosion Control of Steel Reinforcement in the Simulated Concrete Pore Solution

Corrosion of steel bars in reinforcement concrete is the most important factor in the destruction of concrete structures. Till now, several protection methods for reducing the rate of corrosion of steel in reinforced concrete structures have been used, which corrosion inhibitors due to economical, easy to apply and efficiency, compared to other methods, faced with more attention. In this study, the effects of the simultaneous use of sodium nitrite and sodium-potassium tartrate inhibitors have been investigated. For this purpose, open circuit potential tests, electrochemical impedance spectroscopy and cyclic polarization were used in simulated concrete pore solution. This study aims to reduce the consumption of sodium nitrite due to environmental problems reported for it and also its destructive effects on the mechanical properties of concrete. Electrochemical impedance spectroscopy showed that the combination of these two inhibitors, improves the corrosion resistance by 91%. This rate is higher than the best performance of each of them, and finally, the synergistic parameter of 2/2 was calculated for this combination. According to the scanning electron microscopy images and the parameters obtained from the fitting of the Electrochemical impedance spectroscopy data, it seems that the simultaneous use of these two inhibitors at appropriate concentrations leads to the formation of a flat, uniform and chloride-resistant layer. Also, according to the results of the cyclic polarization test, the simultaneous use of these two inhibitors increases the pitting potential to 691 mV. Generally, it improves the resistance of steel specimens to pitting corrosion.