Abstract: In order to improve the efficiency of coal mining, accelerate the backfilling speed of goaf and reduce the pollution and damage of coal-based solid waste to mining environment, coal gangue-based paste filling materials with fast hardening characteristics are prepared using coal gangue, fly ash, sulphoaluminate cement and persulfate cement as raw materials. The influences of aggregate-cement ratio and water-cement ratio on the macroscopic properties of the specimens are studied through a series of characterization tests such as fluidity, unconfined compressive strength (UCS), water absorption, softening coefficient and so on. The microstructure and curing mechanism of the specimens are analyzed by TG/DTA, XRD and SEM. The results show that when the aggregate-cement ratio is 4:1 and the water-cement ratio is 1.5, the initial fluidity of the specimen is 195 mm, and the 8 h UCS is 3.26 MPa, displaying obvious characteristics of early strength and fast hardening, and the UCS at 3, 7, and 28 d are 5.56, 5.66, and 6.61 MPa, respectively. The water absorption rate of the sample at 28 d age is 16.86%, and the softening coefficient is 0.90, indicating its excellent water resistance. The phase composition and micro-morphology analyses show that the early unconfined compressive strength of the filling specimens mainly comes from the accumulation and filling benefits of the gangue aggregate as well as the formation of a large amount of ettringite (AFt) in the cementation part. Moreover, the raw materials such as fly ash induce a pozzolanic reaction and react synergistically with persulfate cement, generating a certain amount of hydration products in the later period of curing, which further improves the densification and mechanical properties of the filling specimens. The results obtained in our current research can provide experimental basis and theoretical guidance for the development and practical application of new coal gangue-based green filling materials.

Key words: coal gangue, filling materials, unconfined compressive strength, water resistance, curing mechanism

摘要： 为提高煤矿开采效率，加快煤矿采空区回填速度，降低煤基固废物对矿区环境的污染与破坏，本工作以煤矸石、粉煤灰、硫铝酸盐水泥、过硫酸盐水泥为原料，制备了煤矸石基快硬膏体充填材料。通过开展流动度、无侧限抗压强度、吸水率及软化系数等试验，研究了水胶比和骨胶比对试样宏观性能的影响，并对试样的微观结构与固化机理进行分析。研究结果表明，当骨胶比为4:1，水胶比为1.5时，试样的初始流动度为195 mm，8 h无侧限抗压强度为3.26 MPa，呈现明显的“早强快硬”特征，3, 7, 28 d无侧限抗压强度分别为5.56, 5.66和6.61 MPa。同时，28 d龄期试样的吸水率为16.86%，软化系数为0.90，耐水性优良。相组成与微观形貌分析表明，充填试样的早期无侧限抗压强度主要来源于煤矸石骨料的堆积填充效益与胶结部分中大量形成的钙矾石(AFt)，而后期粉煤灰等原料发挥火山灰效应，并与过硫酸盐水泥协同反应，其水化产物可进一步提高充填试样的致密度与力学性能。本研究可为新型煤矸石基绿色充填材料的开发与实际应用提供实验依据和理论指导。

关键词: 煤矸石, 充填材料, 无侧限抗压强度, 耐水性, 固化机理