Valorisation of Alkali–Thermal Activated Red Mud for High-Performance Geopolymer: Performance Evaluation and Environmental Effects

作者：Zhiping Li, Haifeng Dong, Yuwen Wang, Jianbing Men, Junqiang Wang, Xiushao Zhao, Sikai Zou · 发表于：Preprints.org · 年份：2025 · DOI：10.20944/preprints202507.0800.v1 · 被引用次数：12 · 研究领域：Bauxite Residue and Utilization、Recycling and utilization of industrial and municipal waste in materials production、Innovations in Concrete and Construction Materials

This study investigates the influence of SiO₂/Al₂O₃ molar ratios (2.25–3.00) and the replacement of red mud (RM) with GGBS (50–63%) on the performance of RM-based geopolymers to address the environmental issues posed by RM, including its high alkalinity and heavy metal content. The results revealed that increasing the SiO₂/Al₂O₃ molar ratios and replacing RM with GGBS reduced the fresh properties of RM-based geopolymers. The increase of the SiO₂/Al₂O₃ molar ratio was beneficial to the compressive strength development of RM-based geopolymers, which was likely related to the high concentration of soluble silicates. The RM-based geopolymers also exhibited higher compressive strength than those with lower GGBS addition. Moreover, the drying shrinkage and water permeability of RM-based geopolymers increased with an increase in the SiO₂/Al₂O₃ ratio and the amount of GGBS addition. Sustainability analysis showed that the CO₂ emissions of RM-based geopolymers were related to the SiO₂/Al₂O₃ ratio. In comparison to other RM-based geopolymers, the CO₂ emissions and costs in this study were reduced by 13.13%–44.33% and 3.64%–39.68%, respectively. This study discusses the effects of the SiO₂/Al₂O₃ molar ratios on the reaction process and strength formation mechanism of RM-based geopolymers, which provides an effective strategy for the resource utilization of RM.