Characterisation of magnetic properties in cementitious composites for advanced wireless power transfer systems using magnetic sand, magnetite powder, GGBFS, and silica fume

• Natural magnetic sand used as a sustainable aggregate in cementitious composites. • Hybrid mixes incorporate GGBFS and silica fume to reduce embodied carbon. • Magnetic and mechanical behaviours assessed for wireless power transfer potential. • Magnetic sand enhances flux density without compromising strength performance. • MP2SF20 mix (2 % magnetite + 20 % silica fume) shows optimal magnetic response. The integration of natural stone–derived materials into sustainable cementitious systems offers a promising route toward potentially lower environmental impact and multifunctional construction. This study investigates the magnetic and mechanical characteristics of cementitious composites incorporating naturally sourced magnetic sand, magnetite powder, ground granulated blast-furnace slag (GGBFS), and silica fume. The primary objective is to evaluate the feasibility of using these hybrid natural–industrial composites in structural applications that enable wireless power transfer (WPT) and magnetic sensing, particularly for infrastructure such as road pavements and railway slabs. Ten mix designs were prepared using magnetic sand as a replacement for conventional quartz sand, with varying proportions of magnetite powder, GGBFS, and silica fume. Mechanical and magnetic assessments were conducted to ensure both structural integrity and functional performance. Magnetic flux coupling was measured using a data logger and oscilloscope, while compressive strength and workability tests verified the suitability of the materials for construction use. Results indicate that plain Portland cement concrete acts as a magnetically weak matrix, and therefore does not significantly influence magnetic behaviour compared with magnetic additives. However, incorporating natural magnetic sand markedly enhances magnetic flux density without compromising mechanical strength. Further, the inclusion of silica fume and GGBFS improves microstructural compactness and has the potential to reduce the embodied CO₂ associated with the binder phase by partially replacing Portland cement. The mix containing 2% magnetite powder and 20% silica fume (MP2SF20) exhibited the highest magnetic flux response and superior strength retention. This research demonstrates that combining natural ferromagnetic sands with low-carbon supplementary binders can yield structurally sound, sustainable, and magnetically functional composites, bridging the gap between traditional stone-based materials and next-generation innovative construction systems.