Studies on galvanized carbon steel in Ca(OH)2 solutions

Tlte beliavior of galvanized carbon steel samples was studied in Ca(OH)2 solutions, simulating the alkaline environment in reinforced concrete. Under shorter periods, it was seen that a passive layer was formed on the surface of the zinc coating. Tlie film, however, was not stable for large periods of time. Tliis was revealed by the long duration tests where the passive layer was disrupted and the carbon substrate was protected sacricially by zinc dissolution. The presence of chlorides accelerated the passive layer breakdown. The role of calcium nitrite in inhibiting the corrosion process of zinc was also studied. It was found that zinc was not protected by nitrite in the presence of chloride ions. Tlie inhibitor, however, significantly reduced the corrosion rate of the underlying steel. Copyright ©2000, American Concrete institute. All rights reserved,.