Experimental study on buildability of 3D-printed cement-based structures using aluminium sulphate.

Recent advancements in Additive Manufacturing (AM), specifically in 3D printing of cement-based materials, have highlighted the necessity for enhancing buildability through optimising material properties and printing parameters. This study explored the effects of printing speed, layer height and the use of aluminium sulphate (Al2(SO4)3) as an accelerator on the buildability of small-scale cement-based structures. Utilising mastercrete cement, fly ash and ground granulated blast-furnace slag (GGBS), the influence of the above variables on the structural integrity of 3D-printed layers was examined. Experimental results indicated that increasing the aluminium sulphate concentration to a 45% concentration improved buildability. This optimal concentration supported samples of 14 layers to be built, demonstrating enhanced stiffness and load-bearing capacity. The optimal printing speed of 20 mm/s achieved a balance between material deposition and setting time, facilitating the printing of 10 stable layers without accelerator. Conversely, increasing the printing speed resulted in a reduced buildability, due to poor adhesion between layers. Layer height analysis revealed that a layer height of 10 mm was most effective, ensuring proper interlayer adhesion and structural stability. These parameters significantly enhanced the buildability and collectively supported the structural integrity and feasibility of cement-based 3D printing for construction applications.