Optimization of printing precision and mechanical property for powder-based 3D printed magnesium phosphate cement using fly ash

Fly ash (FA) is employed to optimize the hydration process of powder-based (inkjet) 3D printed magnesium phosphate cement (MPC), aiming to enhance the printing precision and mechanical properties of powder-based 3D printed structures. This paper systematically evaluates the effects of FA on the printability, printing precision, and mechanical properties of printed MPC. In addition, SEM, XRD, and X-CT are used to analyze the hydration morphology, products, and pore structure of printed MPC, respectively. The test results reveal that the proper addition of FA can effectively optimize the penetration process between the binder and powder bed to improve the printing precision of powder-based 3D printed MPC with the minimum printing size error controlled within 1%, which also achieves the maximum compressive strength of 10.1 MPa at 28d under room environment curing. Due to the pozzolanic and micro-aggregate effects, FA can significantly improve the hydration degree and optimize the pore structure of printed MPC with the total porosity decreased by 24%. The high precision of the printed complicated electromagnetic metasurface models further demonstrates the applicability of powder-based 3D printing with FA-optimized MPC.