Effects of steel slag admixture with GGBFS on performances of cement paste and mortar

The feasibility of steel slag powder as a combined admixture with ground granulated blast furnace slag (GGBFS) in cement-based materials was explored. The effects of steel slag powder on normal consistency water requirement, setting times, fluidity, mechanical strength and hydration products of cement paste/mortar were studied. The results showed that the optimum addition content of steel slag powder in combined admixture was less than 20%. Steel slag powder decreased normal consistency water requirement, retarded setting time of cement paste and had positive effects on the fluidity of cement mortar. As the curing ages increased, the flexural and compressive strengths of mortars with combined admixture increased rapidly to even higher than that of the blank sample. Additionally, early-age strength could be improved by increasing the specific surface area of the steel slag powder. Hydration products mainly included calcium-silicate-hydrate (C-S-H) gel, C-S-Al-H gel and Ca(OH)₂. Mixing these two powders of GGBFS and steel slag powder had a positive effect regarding the hydration of steel slag powder. Additionally, this research contributes to understanding of how to manage industrial wastes sustainably and has the potential to provide several important environmental and economic benefits.