Effect of calcination on the physical, chemical, morphological, and cementitious properties of red mud

Red mud (RM), a by-product of aluminum production, poses environmental concerns with its disposal. This study explored calcining RM at 600 °C for 0–6 hours to utilize it as a cement substitute. Calcination up to 2 hours decreased particle size and increased surface area due to moisture loss, while further calcination reversed these effects. XRF analysis showed high Fe2O3, Al₂O₃, SiO₂ contents. XRD revealed goethite transformed to hematite and gibbsite to alumina. SEM images displayed a loose then denser structure over time. 10% calcined RM incorporated into cement showed 2-hour calcined RM exhibited optimal properties, including high strength (46.27 MPa) and strength activity index (117.24%). SEM confirmed improved C-S-H gel formation with 2-hour calcined RM. In summary, calcining RM optimally at 600 °C for 2 hours allows its effective use as a sustainable cementitious material, providing environ- mental and technical benefits of RM utilization in cement composites.