Zhang Wei, Liu Xiaoming, Wang Yaguang, Li Zepeng, Li Yong, Ren Yongyu
School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
State Key Laboratory of Advanced Metallurgy, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, China; School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
J Hazard Mater. 2021 May 15;410:124592. doi: 10.1016/j.jhazmat.2020.124592. Epub 2020 Nov 17.
Bayer red mud (RM) occupies a large amount of land, which excessive Na seriously damages groundwater resources. In this research, a RM based cementitious material (RMC) composed of RM and ordinary Portland cement (OPC) was developed. It is interesting to find that a binary reaction consisting of cement hydration and geopolymer reaction in RMC. The mechanical and Na consolidation rate of RMC were improved by the synergistic effect of binary reaction. The results indicated that the compressive strength of RMC is the highest and reaches 32.5R OPC when the mass ratio of CaO/(SiO+AlO) is 1.37, and the Na leaching concentration is environmentally acceptable. The 7 days compressive strength of RM-based cementitious material No.2 (RMC2) can reach 93.80% of that of 28 days. As the predominant hydration products, cement hydration product (Ca(SiO)(OH)) and geopolymer (CaAlSiO·2HO and NaAlSiO·2HO) were principally responsible for the strength development of RMC2 at 7 days. The optimal densification microstructure and [SiO] polymerization structure was presented in RMC2. The supreme Na consolidation rate was 99.23% in RMC2 due to the cooperation of physical fixation and [Si(Al)O] charge balance principle. This paper provides a fresh theoretical guidance for the utilization of RM and its Na in building materials.
拜耳赤泥（RM）占用大量土地，其中过量的钠严重损害地下水资源。在本研究中，开发了一种由RM和普通硅酸盐水泥（OPC）组成的基于赤泥的胶凝材料（RMC）。有趣的是，在RMC中发现了由水泥水化和地质聚合物反应组成的二元反应。二元反应的协同作用提高了RMC的力学性能和钠固化率。结果表明，当CaO/（SiO+AlO）的质量比为1.37时，RMC的抗压强度最高，达到32.5R OPC，且钠浸出浓度符合环境要求。基于赤泥的胶凝材料2号（RMC2）的7天抗压强度可达到28天抗压强度的93.80%。作为主要的水化产物，水泥水化产物（Ca（SiO）（OH））和地质聚合物（CaAlSiO·2HO和NaAlSiO·2HO）主要负责RMC2在7天时的强度发展。RMC2呈现出最佳的致密微观结构和[SiO]聚合结构。由于物理固定和[Si（Al）O]电荷平衡原理的协同作用，RMC2中的最高钠固化率为99.23%。本文为赤泥及其钠在建筑材料中的利用提供了新的理论指导。
