Effect of coarse aggregate on printability and mechanical properties of 3D printed concrete

Increasing the dosage of the coarse aggregate is always desirable for 3D printed concrete (3DPC), which is essential for promoting the practical application of 3DPC. This study investigated the effect of coarse aggregate on the printability and the mechanical properties of 3DPC. The internal pore distribution of 3DPC with different coarse aggregate dosages was characterized using X-ray computed tomography (X-CT). It was observed that the mechanical properties of 3DPC with coarse aggregate are closely related to printability. The change in printability caused by the incorporation of the coarse aggregate can effectively improve the mechanical strength of the interfaces between the vertical and horizontal filaments, and attenuate the mechanical anisotropy phenomenon in 3DPC, but does not enhance the overall compressive strength. Water-retention agent is crucial for fabricating uniform 3DPC with coarse aggregate. This research advances the capabilities of understanding the printing technology for 3DPC and designing 3DPC with coarse aggregate.