Performance of Cementitious Composites with Bayer Red Mud as a Partial Cement Replacement

This study investigates the utilization of Bayer red mud (BRM) from Shandong Xinfa Group as a partial cement replacement, with replacement levels of 0.5%, 1%, 5%, 10%, and 15% by mass. The effects of BRM incorporation on setting time, compressive strength (at 3 and 28 days), and microstructural properties were systematically evaluated. Results indicate that the addition of BRM prolongs setting times but remains within standard limits. Compressive strength remained comparable to the control group at replacement levels up to 5%, while higher substitutions (10% and 15%) led to significant reductions. Microstructural analyses via XRD, TG/DTG, and SEM revealed that BRM primarily acts as a micro-filler and nucleation site, participating partially in hydration reactions. Leachability tests (TCLP) confirmed that all heavy metal concentrations in BRM-blended mortars were below regulatory thresholds, demonstrating minimal environmental risk. The findings support the feasibility of using Xinfa BRM as a supplementary cementitious material at doses below 10%, contributing to sustainable solid waste management in the alumina industry.