Sustainable belite-ye’elimite-ferrite cement: utilizing ladle metallurgy furnace steel slag for low-cost and carbon-efficient production

Belite–ye’elimite–ferrite (BYF) cement is a promising low-carbon alternative to Portland cement, but its adoption is limited by reliance on high-grade bauxite. This study demonstrates a composition-driven raw-mix design enabling ultra-high utilization (82 wt.%) of ladle metallurgy furnace (LMF) steel slag for BYF clinker production without external alumina sources. Clinker synthesized at 1300 °C was blended with 5–25 wt.% gypsum to evaluate hydration, phase evolution, dimensional stability, and strength. Gypsum content influenced not only hydration kinetics but also stabilization of slag-derived phases; increasing sulfate availability suppressed periclase-related expansion, indicating that dimensional stability is governed by phase evolution rather than gypsum content alone. The 10 wt.% gypsum formulation showed the most balanced performance, achieving strength comparable to Portland cement with a favorable ettringite–AFm–strätlingite assemblage. Substituting limestone with LMF slag reduced calcination-related CO2 emissions by ∼86%. These results demonstrate a viable pathway for producing low-cost, low-carbon BYF cement using industrial waste.