Anodic corrosion inhibitors against chloride induced corrosion of concrete rebars

Abstract

The effect of anodic inhibitors [calcium nitrate Ca(NO3)2, calcium nitrite Ca(NO2)2 and potassium nitrate NaNO2] has been evaluated using cylinders with steel rebars exposed to the following environments: in the marine tidal zone, at roof top and in air of 38°C and 90% relative humidity for 4 years. The experiments showed that the half cell potentials were more negative than the visual inspections proved when anodic inhibitors are used. Inhibitor dosage on 3–4% of cement weight seems sufficient to protect the rebar against corrosion. Capillary absorption experiments showed that the concrete porosity was unaffected by the inhibitors. The concentration profiles of chloride, nitrite and nitrate were investigated with respect to leaching. However, it was difficult to find the background level of nitrite due to possible chemical alteration.