Corrosion of galvanized steel reinforcements in alkaline solutions: Part 1: Electrochemical results

Abstract

The behaviour of galvanized corrugated reinforcing bars has been studied in 0·001–1·5M solutions of KOH and NaOH designed to simulate aqueous environments found in concrete pores. Specimens were immersed for 33 days in polyethylene cells, corrosion potential, corrosion intensity, and pH being monitored throughout. Polarization curves were also obtained after 50 min and ∼ 33 days' immersion. It was possible to establish pH ranges in which localized corrosion (< 12), stability (12–13·4), and complete dissolution of the galvanic coating (> 13·4) occurred. A white, dusty corrosion product was observed on most specimens at the conclusion of the tests. Hydrogen dissolution on the galvanized bars occurred at pH values higher than the threshold level of 12·8$\pm$0·1.