Performance Assessment of BOF steel slag as fine aggregate in the development of fly ash based geopolymeric mortar

This study focused on the partial replacement of river sand in fly ash-based geopolymeric mortar with Basic Oxygen Furnace (BOF) steel slag fine aggregate. The research aimed to create eco-friendly geopolymeric mortar using fly ash, steel slag and an alkaline solution of sodium hydroxide and sodium silicate. Physical testing against flowability, bulk density and water absorption has been conducted, and mechanical behaviour against compressive and flexural strength has also been investigated. However, the raw material and developed mortar have been characterised using Scanning Electron Microscope (SEM) for morphological studies, Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD) for mineralogical studies. Geopolymer mortar with 30% steel slag replacing river sand (30SSM) showed the highest strength, reaching 35MPa in compression and 5.6MPa in flexure. This strength can be attributed to the strong and flexible (ductile) characteristics of steel slag when combined with the geopolymeric paste. Additionally, the angular and rough surface texture of steel slag enhances the physical bonding within the matrix. This high-volume fly ash (cement-free) based steel slag aggregate geopolymeric mortar offers a sustainable option for various building components like paver blocks, bricks etc.