Waste-derived aggregates in 3D printable concrete: Current insights and future perspectives

The growing demand for sustainable construction practices has driven significant interest in integrating waste-derived aggregates into 3D printable concrete. However, challenges remain in ensuring that these materials meet the performance requirements of 3D printable concrete. To this end, this paper examines the viability, challenges, and innovations in replacing natural aggregates with waste-derived aggregates in 3D printable concrete. The aggregates are categorized into four main types based on their origin: construction and demolition waste, end-of-life manufactured materials, forest and agricultural residues, and industrial or synthetic aggregates from secondary resources. Subsequently, the influence of these materials on rheological properties, mechanical properties, and durability is thoroughly reviewed. Finally, novel applications of waste-derived aggregates are discussed, including functionally graded concrete, impact-resistant systems, carbon-capturing materials, and magneto-responsive composites, demonstrating the potential of waste-derived aggregates to expand the functionality of 3D printable concrete.