Use of ladle furnace slag as filler replacement in magnesium oxychloride cement: Towards sustainable 3D-printable building composites

In response to the global demand for CO₂ emissions reduction, Portland cement (PC) replacement with more eco-friendly materials has been focused on in material studies. One of the studied alternatives is magnesium oxychloride cement (MOC), which offers excellent mechanical properties and lower production temperatures. The ecological impact of MOC alone is significant, but if we incorporate waste material as a filler replacement in MOC composites, we can decrease overall emissions even more. In this paper, we focused on the development of an eco-friendly material with a safely incorporated ladle furnace slag (SL). Firstly, the SL was characterized by numerous analytical methods (XRF, XRD, SEM, EDS, STA-MS) to attain knowledge about its elemental and phase composition. In the following step, MOC composite materials with SL used as a silica sand partial replacement were prepared by casting. Such prepared materials were then characterized by XRF, XRD, SEM, EDS, and MIP. Furthermore, their structural and mechanical properties were assessed. Based on the obtained results, an optimized composition of mixtures was used for 3D printing to demonstrate the suitability of this material for this purpose. Finally, X-ray computed micro-tomography imaging was used to study the quality of printed cubes, in particular porosity and the amount of macroscopic defects. This paper presents an innovative approach in which waste SL from steel production can replace silica sand filler in significant quantities, demonstrating that such a designed material is suitable for additive manufacturing.