主办单位：煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
Orthogonal optimization of the ratio of nano-silica sol-EVA-fly ash cement-based composite slurry and the effect on its physical properties
SHEN Yuxu;CHAI Zhaoyun;SUN Haocheng;LIU Xiangyu;GUO Junqing;XIAO Chang;LI Tianyu;XIN Zipeng;SHI Qinbin
针对传统水泥基浆材不能满足煤矿大变形巷道注浆加固实际需求的难题，通过添加纳米硅溶胶、乙烯−醋酸乙烯共聚物(EVA)和粉煤灰对普通硅酸盐水泥进行改性获得高性能复合浆材。采用正交试验和极差分析法系统研究复合浆材物理力学性能的变化规律，确定最优配比，并进一步分析最优配比复合浆材与纯水泥的物性差异，构建复合浆材的水化反应机理模型，阐明其加固破碎岩石的力学特性。研究结果表明，复合浆材最优配比为：水灰比0.7，粉煤灰掺量15%，硅溶胶掺量2%，EVA掺量7.5%；相较于纯水泥，复合浆材流变性略有下降，但浆液稳定性、力学性能等均有显著提升，初凝时间缩短了38.9%，终凝时间缩短了53.8%，析水率降低了60%，结石率提高了3.3%，单轴抗压强度提高了39.1%，抗拉强度提高了97.2%，拉压比提高了41.7%；硅溶胶和粉煤灰在不同时期与Ca(OH)2发生火山灰反应生成更多水化硅酸钙(C-S-H)和水化铝酸钙(C-A-H)，促进复合浆材的水化反应，并加速EVA成膜，使结石体更加致密；复合浆材注入量和胶结体单轴抗压强度均随注浆压力的增大而增加，随Talbot指数的增加，抗压强度先增大后减小，破坏形式多呈鼓状，剪胀变形明显；当注浆压力大于2 MPa，Talbot指数为0.5时，胶结体强度较大，破坏较小。本研究为水泥基复合浆材早期强度、增韧改性提供了可行途径。
To address the problem that traditional cement-based slurry materials cannot meet the actual demand for grouting and reinforcement of large deformation roadways in coal mines, some high-performance composite slurry materials are obtained by modifying ordinary Portland cement with nano-silica sol, ethylene-vinyl acetate copolymer (EVA) and fly ash. The orthogonal test and extreme difference analysis are used to systematically study the variation of the physical and mechanical properties of the composite slurries, determine the optimal ratio, and further analyze the difference in the physical properties between the optimal ratio of composite slurries and pure cement, construct the hydration reaction mechanism model of the composite slurries, and elucidate the mechanical properties of the composite slurries for reinforcing broken rocks. The results of the study show that the optimum proportion of composite slurry is 0.7 water-cement ratio, 15% fly ash, 2% silica sol and 7.5% EVA. Compared with pure cement, the rheology of composite slurry is slightly decreased, but the stability and mechanical properties of the slurry are significantly improved, with the initial setting time shortened by 38.9%, the final setting time shortened by 53.8%, the precipitation rate reduced by 60%, the stone rate increased by 3.3%, the uniaxial compressive strength increased by 39.1%, the tensile strength increased by 97.2%, and the tensile/compression ratio increased by 41.7%. Silica sol and fly ash undergo volcanic ash reaction with Ca(OH)2 to generate more calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H) at different times, which promotes the hydration reaction of the composite slurry and accelerates the film formation of EVA to make the stone body more dense. The injection volume of the composite grout and the uniaxial compressive strength of the bonded body both increase with the increasing grouting pressure. With the increase in the Talbot index, the compressive strength first increases and then decreases. The failure mode is often characterized by bulging, and shear dilation deformation is pronounced. When the grouting pressure exceeds 2 MPa and the Talbot index is 0.5, the bond strength of the grout is higher, and the damage is reduced. This study provides a feasible way for early strength and toughening modification of ce-mentitious composite pastes.
nano-silica sol;EVA;fly ash;ordinary Portland cement;orthogonal test
主办单位：煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会
煤炭学报 
2024年第06期 
