Evaluation of a composite corrosion inhibiting admixtures and its performance in Portland pozzolana cement

The effect of various inhibitive and complexing ions like hydroxide, citrate and stannate for the corrosion of steel in concrete was studied by weight loss measurements, potential–time behaviour studies, potentiodynamic polarisation studies and electrochemical impedance measurements. The salient features of these investigations were, in 100% PPC extract the passivity of steel was readily destroyed even in the presence of 10 000 ppm of chloride. However, in 100% PPC extracts containing inhibitive and complexing agents like hydroxide, citrate and stannate, the passivity of steel was maintained even in the presence of 30 000 ppm of chloride. The addition of inhibitive ions like hydroxide, citrate and stannate decreased the corrosion of steel in simulated concrete environments. Citrates, stannates and calcium oxide are very effective inhibitors for corrosion of steel in Portland pozzolana cement.