Use of Supplementary Cementing Materials to Increase the Resistance to Chloride Ion Penetration of Concretes Cured at Elevated Temperatures

Abstract

It has long been known that elevated curing temperatures, while accelerating the early strength gain of concrete, reduce the ultimate strength. Recent research has shown that elevated curing temperatures can also reduce the resistance to chloride diffusion of plain portland cement concretes. This paper describes an investigation of the chloride penetration of 0.40 and 0.50 water-cement ratio (w/c) concretes containing either 5 percent silica fume or 30 percent blast furnace slag (substitution by mass) cured at elevated temperatures. Plain portland cement concretes were used as controls. The concretes were cured at constant temperatures of 23, 50, or 70 deg C to a degree of hydration of approximately 70 percent. Supplemental tests were performed on concretes cured overnight using a steam-curing regime. Both the silica fume and slag concretes performed better than the controls in these tests.