In 2024, the Royal Swedish Institute of Technology introduced Limestone Calcined Clay Cement (LC³), which garnered global attention due to its significantly reduced carbon emissions. LC³ is formulated from clinker, calcined clay (metakaolin, MK), and calcium carbonate (CC). However, with the dwindling reserves of clay and limestone in countries like China and the increasing accumulation of industrial waste such as red mud (RM), substituting RM for MK and CC in LC³ presents a promising alternative. This study investigated the influence of replacing MK and CC with RM on the properties of mortar, alkali penetration, and microstructure. X-ray diffraction (XRD) was employed to analyze mineral composition, scanning electron microscopy (SEM) to examine microstructure, and energy-dispersive X-ray spectroscopy (EDS) to assess elemental distribution and alkalinity. The results indicate that RM enhances fluidity, prolongs setting time, and increases compressive strength, albeit at the expense of early flexural strength. SEM observations reveal denser composites attributed to the formation of C-A-H and C-A-S-H gels, while EDS analysis shows that ammonium carbonate mitigates calcium ion migration.

Keywords: Limestone calcined clay cement, Red mud, Alkalinity, Metakaolin, Hydrated aluminum calcium silicate.