Voltammetric behaviour of iron in cement Part IV: Effect of acetate and urea additions

The effects of acetate and urea on the cyclic voltammetric behaviour of iron in cured cement paste were investigated. The voltammetric results indicate that sodium acetate and urea do not cause depassivation of iron in cement. The addition of ~0.2 M of either sodium acetate or urea prevents depassivation of iron in cement exposed to 0.1 M sodium chloride upon potential cycling. However, the addition of even relatively high concentrations of sodium acetate or urea (e.g. 1.0 M), cannot prevent depassivation by 0.2 M sodium chloride upon potential cycling. The voltammetric results also indicate that sodium acetate, urea, and calcium magnesium acetate (CMA) are only marginally effective as corrosion inhibitors for reinforced concrete, compared with an inhibitor of known effectiveness, such as sodium nitrite. Thus, while acetates and urea may well be ‘non-corrosive’ deicers when used by themselves, large amounts of sodium chloride should not be mixed with acetates or urea as a cost-reducing measure.