Wang Kai, Guo Siyang, Ren Jiahui, Chen Pengyu, Zhang Qihao
School of Civil Engineering and Architecture, Henan University, Kaifeng 475000, China.
Nanomaterials (Basel). 2024 Dec 13;14(24):1997. doi: 10.3390/nano14241997.
The increasing incidence of structural failures, such as cracks and collapses, in rock masses within mines, tunnels, and other civil engineering environments has attracted considerable attention among scholars in recent years. Grouting serves as a principal solution to these issues. The Renlou Coal Mine in the Anhui Province is used as a case study to evaluate the effectiveness of nanosilica (NS) as an additive in ultrafine cement (UC), introducing a novel grouting material for practical applications. This study investigates the physical and microscopic properties of a UC-ultrafine fly ash (UFA) mixed slurry containing powdered NS. Slurries of pure UC, UFA-blended UC, and UFA-blended UC with NS were prepared, and their viscosity, water precipitation rate, and compressive strength were evaluated. Scanning electron microscopy and X-ray diffraction were used for microscopic analyses. The results showed that the addition of UFA and NS to the UC slurry induced a more compact structure with reduced porosity. It was found that the viscosity and 7 d and 28 d compressive strengths of the slurry containing 50% UFA decreased by 91%, 51%, and 29.2%, respectively, and the water separation rate increased by 306.5%. The decrease in early strength was more pronounced, and the UFA content should not exceed 25%. Compared with the slurry without NS, the viscosity and 7 d and 28 d compressive strength of the slurry containing 1.5% NS increased by 216%, 51.2%, and 37%, respectively, and the water separation rate decreased by 45%. Notably, when the NS content is 1.5%, the performance of cement slurry is improved the most, and more C-S-H gel is produced. Cement consumption costs could be lowered and slurry performance improved by replacing a part of the cement with UFA and NS. Finally, orthogonal tests were conducted to select the optimal proportions for cement grouting. The optimal blend was determined to be composed of 20% UFA and 1.5% NS, with a water-cement ratio of 0.6. The study's results not only demonstrate that NS has a good effect on improving the performance of cement-based grouting materials but also provide new insights for the design and application of grouting support in underground engineering.
近年来，矿山、隧道及其他土木工程环境中岩体结构破坏（如裂缝和坍塌）的发生率不断上升，引起了学者们的广泛关注。注浆是解决这些问题的主要方法。以安徽省任楼煤矿为例，评估纳米二氧化硅（NS）作为超细水泥（UC）添加剂的有效性，引入一种新型注浆材料用于实际应用。本研究调查了含粉状NS的UC - 超细粉煤灰（UFA）混合浆液的物理和微观性能。制备了纯UC、UFA混合UC以及含NS的UFA混合UC浆液，并评估了它们的粘度、析水率和抗压强度。采用扫描电子显微镜和X射线衍射进行微观分析。结果表明，向UC浆液中添加UFA和NS可使结构更致密，孔隙率降低。发现含50% UFA的浆液粘度以及7天和28天抗压强度分别降低了91%、51%和29.2%，析水率提高了306.5%。早期强度下降更明显，UFA含量不应超过25%。与不含NS的浆液相比，含1.5% NS的浆液粘度以及7天和28天抗压强度分别提高了216%、51.2%和37%，析水率降低了45%。值得注意的是，当NS含量为1.5%时，水泥浆性能改善最为明显，生成了更多的C - S - H凝胶。用UFA和NS替代部分水泥可降低水泥消耗成本并改善浆液性能。最后，进行正交试验以选择水泥注浆的最佳配比。确定最佳配比为20% UFA、1.5% NS，水灰比为0.6。该研究结果不仅表明NS对改善水泥基注浆材料性能有良好效果，还为地下工程注浆支护的设计和应用提供了新的思路。
