Utilisation of Steel Slag Aggregate in Sustainable Paver Block Production
The depletion of natural aggregate (NA) resources and the escalating environmental concerns associated with aggregate mining necessitate the development of sustainable alternative aggregates for concrete applications. Steel slag aggregate (SSA), a by-product of steel manufacturing, offers a promising alternative due to its favourable mechanical and mineralogical characteristics, yet it remains underutilized. This study investigates the feasibility of using SSA as partial and full replacements for coarse and fine natural aggregates in paver block production. A systematic experimental programme was conducted, including physical and chemical characterisation of SSA and NA, morphological assessment through angularity and surface roughness analysis, and evaluation of the engineering performance of SSA-incorporated paver blocks. Six mixtures were developed, comprising coarse SSA (CSA), fine SSA (FSA), and Total SSA replacement. The results demonstrated that SSA possesses superior physical and mechanical properties, including higher specific gravity, greater impact and abrasion resistance, and approximately 31% higher crushing strength than NA. Morphological analyses further revealed significantly higher angularity and surface roughness of SSA, contributing to improved aggregate interlocking and bonding characteristics. Further, both CSA and FSA incorporation increased the optimum moisture content and maximum dry density of paver blocks because of their higher water absorption and density. All SSA mixtures exhibited higher compressive, split tensile, and flexural strengths compared with the control mix, with the Total SSA mixture achieving the highest improvements of 42%, 62%, and 45%, respectively. In addition, SSA significantly improved abrasion resistance due to its higher hardness and stronger aggregate–paste interaction, although a moderate increase in water absorption was observed. Overall, the findings demonstrate that SSA is a promising sustainable alternative to natural aggregates for producing durable paver blocks suitable for pavement applications.