Total shrinkage, oxygen permeability, and chloride ion penetration in concrete made with white Portland cement and blast-furnace slag

Abstract

This study investigated the influence of slag content and curing time with respect to the total shrinkage, penetration of chloride ions after shrinkage, and oxygen permeability of concrete made with white Portland cement (WPC). Concretes were made with water–binder (w/b) ratios of 0.30, 0.42, or 0.55 and slag contents as a substitute for WPC of 0%, 50%, or 70% and were subjected to moist curing for 3 or 7 days. The same mixtures of gray Portland cement (GPC) were also investigated for comparison purposes. A mixture containing 50% slag in place of WPC that was activated by sodium sulfate (4% by weight of binder) was molded to analyze the influence of the activator on the total shrinkage and chloride penetration of the cement. Before being immersed in a saline solution to determine the chloride penetration, the test samples were submitted to a 91-day drying period. The results demonstrated that the partial replacement of 70% of the white Portland cement by slag reduced the total shrinkage by an average of 39% and 35% and the chloride penetration by 37% and 47% when the concrete samples were cured for periods of 3 and 7days, respectively. Mixtures composed of white Portland cement and slag (50% and 70%) had average oxygen permeabilities of 28% and 56%, respectively, which were lower than those of similar mixtures composed of gray Portland cement.