Alkali-Activated EAF Reducing Slag as Binder for Concrete

Electric arc furnace (EAF) reducing slag is the by-product of EAF steel-making. Currently, reducing slag is considered a waste material by the industry in Taiwan. Since the chemical content of reducing slag is similar to blast furnace slag (BFS), it is expected that reducing slag exhibits a similar pozzolanic effect as the BFS. This study used alkaline activator consisting of sodium silicate and sodium hydroxide to improve the activity of reductive slag so as to replace Portland cement as binder in concrete. Some BFS was used to blend with the reducing slag to enhance the binding quality of alkali-activated mixes. The results show that a blend of 50% BFS and 50% reducing slag can be activated successively with alkali. Also, the sulfate resistance of concrete made with alkali-activated EAF reducing slag is found to be better than that of concrete made with portland cement, while the drying shrinkage of alkali-activated EAF reducing slag concrete is greater than that of portland cement concrete.