Electrochemical methods for evaluating inhibitors of steel corrosion in concrete

Abstract

Electrochemical methods were used to evaluate sodium phosphate and sodium nitrite as inhibitors for the corrosion of steel in saturated calcium hydroxide solution containing chloride ions. The studies included immersion, potentiodynamic, potentiostatic, and galvanostatic tests. The results obtained from these methods were in good agreement. They show that sodium nitrite is an anodic inhibitor which is not effective if its concentration is lower than that of the chloride ions. Sodium phosphate acts as an anodic inhibitor if its concentration is higher than 0·6 times the chloride concentration. It is totally effective when its concentration equals the chloride concentration.