Shao Xiaoping, Wang Zhengchun, Tang Renlong, Zhao Bingchao, Ning Jianbo, Tian Chuang, Wang Wei, Zhang Yibo, Du Xing
Energy School, Xi'an University of Science and Technology, Xi'an 710054, China.
Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an 710054, China.
Materials (Basel). 2024 Dec 10;17(24):6037. doi: 10.3390/ma17246037.
Fly ash-cement composite backfill slurry, prepared by partially replacing cement with fly ash, has been demonstrated to effectively reduce the mine backfill costs and carbon emissions associated with cement production. However, the use of fly ash often results in insufficient early and medium-term strength of the backfill material. To address the demand for high medium-term strength in backfill materials under continuous mining and backfilling conditions, this study developed a silica fume-fly ash-cement composite backfill slurry. The effects of varying silica fume contents on the slurry's flowability, uniaxial compressive strength, microstructure, and pore characteristics were systematically investigated. The results showed that increasing the silica fume content significantly reduced the slurry's flowability. However, at a silica fume content of 5%, the slurry achieved optimal medium-term strength, with a 14-day uniaxial compressive strength of 3.98 MPa, representing a 25% improvement compared to the control group. A microstructural analysis revealed that a moderate silica fume content promoted the formation of calcium silicate hydrate gel, filled micropores, and optimized the pore structure, thereby enhancing the overall strength and durability of the material. Conversely, an excessive silica fume content above 5% led to a marked decrease in both flowability and strength. Based on a comprehensive evaluation of silica fume's effects on the flowability, strength, and microstructure, the optimal silica fume content was determined to be 5%. This study provides a theoretical basis and practical guidance for improving the efficiency of continuous mining and backfilling operations, and for designing high-performance backfill materials suitable for continuous mining and filling conditions.
用粉煤灰部分替代水泥制备的粉煤灰 - 水泥复合充填料浆，已被证明能有效降低矿山充填成本以及与水泥生产相关的碳排放。然而，使用粉煤灰往往会导致充填料的早期和中期强度不足。为满足连续采矿和充填条件下对充填料中期高强度的需求，本研究开发了硅灰 - 粉煤灰 - 水泥复合充填料浆。系统研究了不同硅灰含量对该料浆流动性、单轴抗压强度、微观结构和孔隙特征的影响。结果表明，增加硅灰含量会显著降低料浆的流动性。然而，当硅灰含量为5%时，料浆获得了最佳的中期强度，14天单轴抗压强度为3.98MPa，比对照组提高了25%。微观结构分析表明，适量的硅灰含量促进了硅酸钙水化物凝胶的形成，填充了微孔并优化了孔隙结构，从而提高了材料的整体强度和耐久性。相反，硅灰含量超过5%会导致流动性和强度显著下降。基于对硅灰对流动性、强度和微观结构影响的综合评估，确定最佳硅灰含量为5%。本研究为提高连续采矿和充填作业效率以及设计适用于连续采矿和充填条件的高性能充填料提供了理论依据和实践指导。
