Effect of Carbonation, Chlorides and Relative Ambient Humidity on the Corrosion of Galvanized Rebars Embedded in Concrete

Abstract

The variation with time of the corrosion rates of galvanized steel and bare steel rebars has been studied as a function of the relative ambient humidity, mortar carbonation and the presence or absence of chloride ions. Corrosion rates are estimated from Rp measurements with electronic compensation for the ohmic drop between the working imd reference electrodes.It is shown that a normal galvanized coating with a continuous layer of practically pure zinc in contact with mortar gives effective protection to the steel reinforcing bars against the aggressive action of carbonation and chlorides. The protective effect of this galvanized coating is much greater under partial immersion conditions of the mortar than in very humid atmospheres, although in the latter case the corrosion rate decreases with time.