Integrated Assessment of Steel Slag Aggregates: Mechanical, Physico-Chemical, Morphological, and Surface Free Energy Properties

The present study explores the feasibility of utilizing steel slag aggregates (SSA) as a sustainable alternative to natural aggregates (NA) in pavement applications. Although the use of industrial byproducts has gained attention, limited understanding exists regarding the physico-chemical, interfacial, mechanical, and morphological characteristics of SSA. To bridge this gap, a comprehensive multidimensional characterization was performed. The findings revealed that SSA outperforms NA in key physical and mechanical properties, exhibiting a 13%–45% reduction in crushing, abrasion, and impact values. Morphological analysis indicated that SSA contains fewer rod and disc-shaped particles, higher angularity, and lower flatness and elongation ratios (<2). Additionally, SSA demonstrated 1.5 to 2 times higher breakage energy and crushing resistance compared to NA. Surface free energy analysis further confirmed the superior bonding affinity of SSA with cement and asphalt binders, due to its higher total surface energy, nonpolar components, and adhesion work. To validate these findings, M40 grade pavement quality concrete (PQC) was formulated with SSA and NA. The SSA-based PQC demonstrated a notable improvement in flexural strength while maintaining workability comparable to the NA mix. These results highlight the significant promise of SSA as a durable and ecofriendly alternative to NA in pavement applications, promoting performance improvement and resource sustainability.