Suitability of Finely Ground Ladle Furnace Slag as a Portland Cement Replacement in Blended Cementitious Binders

Ladle furnace (LF) slag, a by-product of the steelmaking industry, is rich in calcium and silicate phases, compatible with those present in Portland cement (PC); however, its potential suitability as a supplementary cementitious material is largely unknown. In this study, blended Portland mixes containing LF slag in different quantities were produced and evaluated. The partial replacement of PC by LF slag did not impact the workability of the mixes at the replacement levels evaluated. At higher replacement levels, prolonged setting times were identified, consistent with the low hydraulic and limited pozzolanic reactivity of this material. The compressive strength determined in mortars revealed that increasing LF slag content in the mix led to reductions in strength. Changes in the pore-size distribution of the assessed mixes were also detected, particularly in coarser capillary pores, which are responsible for higher mass transport and provide potential routes for ingress of liquids and gases into these binders. These findings provide insight into the limitations and potential strategies for enhancing the performance of LF slag as a partial PC replacement.