Corrosion behaviour of bare and galvanized steel in geopolymer and Ordinary Portland Cement based mortars with the same strength class exposed to chlorides

Highlights: • Geopolymers prolong low polarization resistance of rebars at early age of curing. • Geopolymers lead reinforcements to high polarization resistance after 10 days of curing. • Fly ash geopolymers protect reinforcements during chlorides exposure. • Metakaolin geopolymers do not protect reinforcements during chlorides exposure. - Abstract: The corrosion behaviour of bare and galvanized steel reinforcements in geopolymeric and cementitious mortars, at three strength classes, has been investigated throughout the curing period and exposure to wet-dry cycles in 3.5% NaCl solution. During the curing, the high alkalinity of geopolymers prolongs the active state of both bare and galvanized steel. During the chloride exposure, fly ash geopolymers give the highest protection to reinforcements. The higher alkalinity of geopolymers compared to cement mortars seems to decrease the minimum free chloride threshold necessary to induce corrosion for galvanized steel, but it increases that for bare steel.