Using recycled concrete powder in cement-based materials

Waste concrete, as a representative construction and demolition waste (C&D waste), exhibits a high potential for reuse. During the crushing, screening, and necessary cleaning of waste concrete, recycled powder is produced, which accounts for approximately 20% of the quality of waste concrete. Because of the low activity, large water demand, and potential to cause dust pollution in storage, the handling of this powder poses a considerable challenge to the effective utilization of C&D waste resources. Therefore, this research is aimed at enhancing the utilization of recycled powder, by replacing all or part of the cement with the recycled powder to prepare geopolymer and foam concrete. The mix design method, mixing process, mechanical properties, and durability of recycled powder polymer and foam concrete are examined. Furthermore, the microstructure formation and deterioration mechanism of the recycled powder polymer and foamed concrete are explained in terms of the microscopic morphology, pore structure, interfacial transition zone defects, and interface microhardness.