Properties of inorganic corrosion inhibition admixtures in steel-containing OPC mortars Part 1: Chemical properties

The chemical interaction between corrosion inhibition admixtures and OPC mortar containing chloride, initially 862 mM/l, has been investigated for three inorganic anions: nitrite, borate and molybdate. After 90 days of cure, the admixture anion solubility in cement pore fluid is variable, ranging from ⪕ 15 mM/l for borate and molybdate, implying precipitation of these ions, to 675 mM/l for nitrite. Chloride ion solubility in cement pore fluid decreases in absolute values but, relative to the control, is somewhat enhanced by addition of admixture anions. However, 90 day corrosion rate measurements indicate that all three admixtures inhibit steel corrosion under conditions of high initial Cl concentrations. The specific chemical modes of corrosion inhihition are discussed.