Potential Applicability of Air-Cooled Ladle Furnace Slag Fine Aggregate in Concrete Production

Electric arc furnace oxidizing slag (EAFOS) represents 80% of the electric arc furnace slag generated. Recently, EAFOS has been utilized as high value-added functional aggregate in a growing number of cases for the construction of air-cooling technology that turns EAFOS into fine aggregate-sized particles by spraying it into the air using high-pressure compressed air. Ladle furnace slag (LFS) is a product of the reduction process, accounting for approximately 20% of the steel slag enerated; however, LFS is predominantly landfilled without being utilized. This is mainly because LFS changes into sludge as it is turned into powder during water spray cooling. Therefore, in this study, spherical particles cooled at room temperature were fabricated as fine aggregates using LFS by applying atomization technology that uses high-pressure air in the molten state for the value-added utilization of LFS. Various experiments were performed to examine whether this aggregate can be used as a construction material. The experimental results showed that the air-cooled LFS (ALFS) fine aggregate generated from two different processes met the physical and chemical properties of the fine aggregate required for concrete despite its slightly lower spherical ratio compared to EAFOS aggregate. The volumetric stability experiment results also showed that ALFS fine aggregate is more stable than river sand and standard sand. In addition, the autoclave test results revealed that the mortar produced using ALFS fine aggregate was more stable for expansion than that of comparison groups. These results confirm the applicability of ALFS as an aggregate for construction. However, because the pop-out phenomenon caused by MgO was observed on the surface of some specimens, further research is required for improvement.