Wang Luyao, Wang Qingping, Cai Jingyi, Zhou Feifei, Cheng Zhiwei, Zhang Jiayao
School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China.
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines, Anhui University of Science and Technology, Huainan 232001, China.
Polymers (Basel). 2025 Mar 29;17(7):932. doi: 10.3390/polym17070932.
Coal gangue and flue gas desulfurization gypsum (DG) are industrial by-products whose utilization is critical for sustainable development. This study explores the synergistic activation of coal gangue using DG and lime to develop eco-friendly cementitious materials. Three systems-CF (coal gangue-DG), CL (coal gangue-lime), and CFL (coal gangue-DG-lime)-were designed to investigate the effects of DG and lime on coal gangue reactivity. Unconfined compressive strength tests identified the optimal dosages of DG and lime, while XRD, SEM, TGA-DTG, and NMR analyses were employed to characterize the hydration products and microstructure. The results demonstrated that calcium ions from both lime and DG facilitated the formation of C-(A)-S-H gel, enhancing strength development. However, excessive DG led to undesirable volume expansion due to ettringite overproduction, compromising material stability. Excess lime forms weak Ca(OH) binding phases and causes expansion and cracking from excessive hydration heat, reducing strength and durability. Thus, the optimal DG dosage in the CF system is 70%, and the optimal lime dosage in the CL system is 6%. In the CFL system, 70% DG and 4% lime achieve the best performance. The combined use of DG and lime not only improved coal gangue reactivity but also achieved an optimal balance between strength enhancement and long-term stability, offering a promising approach for sustainable construction materials.
煤矸石和烟气脱硫石膏（DG）是工业副产品，其利用对可持续发展至关重要。本研究探索了利用DG和石灰对煤矸石进行协同活化，以开发环保型胶凝材料。设计了三个体系——CF（煤矸石-DG）、CL（煤矸石-石灰）和CFL（煤矸石-DG-石灰）——来研究DG和石灰对煤矸石反应活性的影响。无侧限抗压强度试验确定了DG和石灰的最佳用量，同时采用XRD、SEM、TGA-DTG和NMR分析来表征水化产物和微观结构。结果表明，来自石灰和DG的钙离子促进了C-(A)-S-H凝胶的形成，增强了强度发展。然而，过量的DG由于钙矾石过度生成导致不良的体积膨胀，损害了材料稳定性。过量的石灰形成较弱的Ca(OH)结合相，并因水化热过高导致膨胀和开裂，降低了强度和耐久性。因此，CF体系中DG的最佳用量为70%，CL体系中石灰的最佳用量为6%。在CFL体系中，70%的DG和4%的石灰具有最佳性能。DG和石灰的联合使用不仅提高了煤矸石的反应活性，而且在强度增强和长期稳定性之间实现了最佳平衡，为可持续建筑材料提供了一种有前景的方法。
