Study on the wave absorption and mechanical properties of recycled cement-Fe3O4 composites

Research on the functionalised application of construction solid waste is key for solving waste pollution and achieving sustainable building materials. This study prepared recycled cement-Fe3O4 composites using recycled concrete powder (RCP) and nano-Fe3O4. The results show that the incorporation of RCP and nano-Fe3O4 has no significant effect on the phase types of the recycled cement-Fe3O4 composites, but significantly improves the wave absorption performance and the effective absorption bandwidth (EAB). When the content of RCP is 10 wt% and that of nano-Fe3O4 is 9 wt%, the composite exhibits excellent wave absorption performance, with a minimum reflection loss of −33.32 dB and an EAB of 9.37 GHz, which are ≈54% and 206% higher than those of pure cement mortar specimens respectively. Meanwhile, it maintains a compressive strength similar to that of pure cement mortar, providing a new solution for sustainable and functional building materials.