Printability and pore structure of 3D printing low carbon concrete using recycled clay brick powder with various particle features

This paper investigates the utilization of recycled brick powder (BP) as supplementary cementitious material to prepare low carbon 3D printing concrete (3DPC). The effect of grinding time on the characteristics of BP was first analyzed, then the effect of BP on the rheology, printability, mechanical properties, and pore structure of 3DPC was studied. Since the porous microstructure of BP particles is destroyed during grinding process, as the grinding time increases, the average particle size and BET specific surface area of BP decrease synchronously. The BP with larger average particle size and specific surface area worsens printing quality and brings to wider interface zone and higher porosity of 3DPC. However, the BP with small average particle size (27.4 μm in this research) hardly affects the rheology and printability of 3DPC, and only slightly decreases the mechanical properties. This research can provide guidance for applying recycled BP to prepare low carbon 3DPC.