Investigation of the major reduction reaction occurring during the passivation of galvanized steel rebars

The corrosion behaviour of zinc plates immersed in calcium hydroxide saturated solutions in the presence of oxygen, air and nitrogen, respectively, was studied. The corrosion resistance was monitored by potentials and corrosion rate measurements. The results obtained were confirmed by further data collected on galvanized rebars embedded in concrete and stored in different curing environments. The results clearly show that oxygen is the main oxidizing agent and indeed not water for the rapid formation of an effective passivation layer on zinc coating.