Corrosion characteristics of steel in solutions derived from cements and blended cements

Potentiodynamic Anodic Polarization techniques were used to investigate the corrosion characteristics of steel in solutions. The solutions were prepared by mixing different cements at a water-binder ratio of 2.0 and extraction after 3 and 7 days. Cements used in this investigation included an OPC with low C3A content, an OPC with high C3A content, a Slag Cement and a Fly Ash Cement. Results indicate that in the absence of chloride ions, the corrosion characteristics of steel in these solutions are very similar to those of steel in lime-saturated water. Despite differences in the rest potentials found in solutions made with the range of binder materials, steel passivation could be observed in all solutions. Passivation imparted to the steel by binder solutions was found to vary in the presence of increasing levels of chloride. A threshold chloride ion concentration for depassivation was established for each binder solution tested. Solutions made from the High C3A Cement and the Slag Cement displayed the best steel passivation characteristics, white the Low C3A Cement solution rated worst.