Effect of Cementitious Blast-Furnace Slag on Chloride Permeability of Concrete
Jere H. Rose
Appears on pages(s):
accelerated curing; blast furnace slag; blended cements; chlorides; concretes; cover; permeability; reinforcing steels; Materials Research
The availability of separately ground granulated iron blast-furnace (GGBF) slag, as a separate cementitious material or supplement, has prompted new research on its effects on concrete properties. One area in which GGBF slag has particular promise in concrete is its ability to alter the permeability characteristics of concrete to the extent that its resistance to chloride intrusion is significantly improved. This paper discusses the ability of GGBF slag-cement mixtures to reduce the potential detrimental effects of chloride intrusion into concrete. Three test methods for chloride penetration were used and the results of each are discussed. The following conclusions were developed. 1. Significant reductions in permeability are achieved as the replacement level of the slag increases from 40 to 65% of total cementitious material by mass. 2. The permeability of concrete containing GGBF slag is less affected by increases in water-cement ratio than concrete containing regular portland cement alone. 3. The detrimental effects of accelerated curing on the permeability of concrete are virtually eliminated with cement blends containing GGBF slag greater than 50%. 4. Concrete containing GGBF slag may require less depth of cover to protect the reinforcing steel than those concretes using portland cement alone.