Comportamento a corrosione di armature zincate in malte geopolimeriche e cementizie a parità di classe di resistenza - Corrosion behavior of galvanized steel reinforcements in geopolymeric and cementitious mortars at the same strength class

The corrosion behavior of galvanized steel rebars embedded in geopolymer mortar was compared to that of the same reinforcements embedded in a cementitious mortar with the same mechanical strength class. The corrosion potential and the corrosion rate of these bars were measured throughout the first month of curing for all manufactured specimens, and then one half was submitted to weekly wet-dry cycles in 3.5% NaCl solution and the other half to weekly wet-dry cycles in tap water after exposure to a chamber with 3% of CO2. In the first month, the high alkalinity of geopolymers delayed the achievement of the galvanized steel passive state, but after reinforcements reached the same corrosion rates of those embedded in the cementitious mortars. In chlorides exposure, the lowest porosity of geopolymers hindered the ingress of chloride ions offering the highest protection to reinforcements. Also in carbonated matrices, during exposure to wet-dry cycles in tap water, galvanized bars had the lowest corrosion rates when embedded in the geopolymeric matrices.