Chloride-Related Phenomena in Limestone Cement Materials: Effect of Mineral Admixtures and Sulfates

摘要

The development of environmentally friendly cementitious materials, efficient in preventing chloride ingress and decreasing reinforcement corrosion risk, is significantly important for structural applications exposed to corrosive conditions. This paper investigates the effect of natural pozzolana, fly ash, blast-furnace slag, and metakaolin on the behavior of portland-limestone cement concretes and mortars during storage in chloride-sulfate and chloride solutions at 5 degrees C (41 degrees F). Acid- and water-soluble chloride contents, and apparent chloride diffusion coefficients, were determined in concretes. Reinforcement corrosion half-cell potential and current density, mass loss of steel reinforcing bars, and carbonation depth were monitored in mortars. The employment of mineral admixtures decreased chloride ingress and reinforcement corrosion during specimens' exposure to chloride solution; however, the presence of sulfates in the corrosive environment prevented their improving effect. Mineral admixtures increased chloride binding and the resistance of concrete against chloride diffusion, while they also showed similar efficiency in preventing reinforcement corrosion. Sulfates facilitated chloride ingress, hindered chloride binding, and promoted reinforcement corrosion.