Valorization of construction and demolition waste in high-performance epoxy composites for sustainable construction

The growing demand for sustainable construction materials has increased interest in the reuse of construction and demolition waste (CDW). However, the application of recycled aggregates in cementitious composites is often limited by their high porosity, water absorption, and negative impact on mechanical properties. This study proposes an alternative approach by incorporating CDW as coarse aggregate in epoxy resin-based composites, aiming to minimize processing complexity and enhance material performance. Recycled concrete and brick aggregates were used in various filling ratios, and the resulting composites were tested for physical and mechanical properties, including compressive strength, bending tensile strength, and microstructural characteristics over three recycling cycles. The results demonstrate that composites fully filled with brick aggregate and partially filled with concrete aggregate achieved compressive strengths up to 60 MPa, exceeding the reference material, while partial filling improved bending tensile strength and reduced brittleness. Microstructural analysis revealed minor changes in resin and aggregate properties after recycling, with no significant impact on overall performance. The composites also showed good water resistance and superior strength-to-area efficiency compared to conventional materials. These findings suggest that epoxy resin-based composites with CDW aggregates can provide a viable lightweight and high-performance alternative for construction applications while contributing to waste management.