The impact of produced hydrogen gas and calcium zincate on changes of porous structure of cement paste in the vicinity of hot-dip galvanized steel

Abstract

Abstract The paper summarizes the impact of produced hydrogen and calcium hydroxyzincate (Ca[Zn(OH)3]2·2H2O) on the formation of the porous structure of cement paste in the vicinity of hot-dip galvanized steel. These substances result from cathodic (hydrogen) and anodic (zincates-formed by reaction with hydroxides) corrosion reactions of hot-dip galvanized steel (or pure zinc) in the cement paste. The cement binder pore structure was studied by means of mercury porosimetry and analysis of scanning electron microscopy and confocal microscopy images. The porosity of the cement paste at the galvanized steel / cement interphase increased as a result of galvanized steel corrosion while hydrogen was formed. Such a porous structure was maintained throughout the maturation of cement paste. Kinetics of galvanized steel corrosion related primarily to water transport through the binder. The formation of calcium zincate did not result in transition of galvanized steel from active to passive state corrosion.