Investigation of the effects of calcium nitrite and polycarboxylate based super plasticizer on corrosion resistance of steel reinforcement in concrete

In this study, the effect of polycarboxylate based plasticizer and 0.1 M nitrite ion on the corrosion behavior of reinforced concrete in 3.5% NaCl (0.6 M) and 5.85% NaCl (1 M) solutions was investigated. Potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) techniques were used. After exposure to the corrosive media, the surface morphology of the metal surface was examined by scanning electron microscopy (SEM). At constant temperature (298 K), the pH of the solutions was adjusted to 8.0. Nitride ion and polycarboxylate based plasticizers inhibit the anodic dissolution rate of reinforced concrete steel in chloride environments. It was determined that nitride ions form as a protective layer on the reinforced concrete steel surface and polycarboxylate based plasticizer makes it difficult to diffuse chloride ions by reducing the amount of space between the aggregates forming the concrete composition. Inhibition effect decreases with increasing chloride concentration.