Mechanical enhancement induced by high interfacial interlocking in cement-based composite mixed with waste printed circuit boards

Waste printed circuit boards produce large amounts of electronic waste and cause environmental concerns due to their non-degradable non-metallic fractions. This study addresses both electronic waste recycling and sustainable construction by incorporating these fractions into cement-based composites to stabilize hazardous components and enhance structural performance. A comprehensive experimental program was conducted, including compressive strength testing, X-ray computed tomography, scanning electron microscopy, heavy metal leaching assessments under neutral and acidic conditions, and life cycle assessment. The results show that incorporating non-metallic fractions of waste printed circuit boards enhanced mechanical performance, with a 14.5 % increase in 28-day compressive strength and significantly improved crack resistance through delayed crack initiation and propagation. Quantitative pore analysis revealed reduced cumulative large-pore volume and a more refined microstructure. These improvements are mainly attributed to the mechanical interlocking provided by the glass fiber coated with residue resin. This interlocking increases the contact area and enhances energy dissipation during the fiber pullout process. Leaching tests confirmed that leachate concentrations of over ten heavy metals remained well below hazardous waste limits under both neutral and acidic leaching conditions. Life cycle assessment results further demonstrated that the composite has a lower carbon footprint and smaller overall environmental impact compared with conventional mortar. This study demonstrates that incorporating the non-metallic fractions of waste printed circuit boards into cement-based composites offers a safe, sustainable, and high-performance material for construction. The research integrates mechanical, microstructural, environmental, and life-cycle perspectives, establishing a novel framework for assessing the electronic waste in construction materials. © 2025 Elsevier Ltd.