Abstract Recycling of red mud (RM) has attracted more attention in recent years due to severe environmental problems caused by landfilling. The effect of composition optimization and Nano-strengthening on the properties of a binder based on RM was studied in this paper. Results showed that modifying ratios of main oxides and adding Nano-SiO2 could obviously affect the mechanical properties and microstructure of the binder. Specimens with high SiO2/Al2O3 molar ratio (S/A) displayed considerable increase in compressive strength, while decreasing Na2O/Al2O3 molar ratio (N/A) improved the workability of the fresh mix. The compressive strength was developed significantly to be 45 MPa at 28 days by adding Nano-SiO2 with 0.4 wt.% of RM. Phase transformation and microstructure change at different stages of RM decomposition and binder geopolyerization were investigated by X-ray diffraction (XRD), Fourier transformation infrared (FTIR) and Scanning electron microscopy (SEM). The results of this study may provide a prospective method to use RM more widely in construction applications. Graphical abstract

中文翻译：

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利用赤泥通过成分优化和纳米强化生产高强度粘合剂

摘要 近年来，由于垃圾填埋造成的严重环境问题，赤泥（RM）的回收利用受到越来越多的关注。本文研究了成分优化和纳米强化对基于RM的粘合剂性能的影响。结果表明，主要氧化物的改性比例和添加纳米SiO2对粘结剂的力学性能和微观结构有明显的影响。具有高 SiO2/Al2O3 摩尔比 (S/A) 的试样的抗压强度显着增加，而降低 Na2O/Al2O3 摩尔比 (N/A) 则改善了新鲜混合物的可加工性。通过添加具有 0.4 wt.% RM 的 Nano-SiO2，在 28 天时抗压强度显着提高至 45 MPa。通过X射线衍射（XRD）、傅里叶变换红外（FTIR）和扫描电子显微镜（SEM）研究了RM分解和粘合剂地质聚合不同阶段的相变和微观结构变化。这项研究的结果可能为在建筑应用中更广泛地使用 RM 提供一种前瞻性方法。图形概要