Corrosion protection of steel in pumice lightweight mortar by coatings

The purpose of this work was to investigate the corrosion resistance of lightweight mortar exposed to corrosive environments. Widespread use of lightweight mortar is attributed to the several advantages it presents; nevertheless its durability is questionable, as far as the corrosion of reinforcing bars is considered, due to its high porosity. Lightweight mortar specimens were produced using two types of Greek cements as well as Greek pumice of volcanic origin; three different organic coatings and a varnish were applied on them. Specimens were either partially immersed in 3.5% NaCl solution or exposed outdoors. The anti-corrosive performance of these systems was investigated monitoring corrosion potentials and mass loss as well as carbonation and chloride diffusion. The results revealed that in all cases the use of protective coatings reduced significantly corrosion of rebars. Among the examined systems the best protection is offered by the aqueous acrylic dispersion containing titanium dioxide.