纤维改性粉煤灰水泥注浆材料的宏微观性能及关联机制研究

Research on Macro and Micro Properties and Correlation Mechanism of Fiber-Modified Fly Ash Cement Grouting Materials

摘要: 为解决煤层底板注浆工程中传统水泥基材料强度不足、环保性差等问题，本文以II级粉煤灰和P·O42.5水泥为基体，引入聚丙烯与玄武岩两种绿色纤维开展改性研究。通过控制粉煤灰掺量70%、水固比1:1、水玻璃掺量3%的基础配方，系统探究纤维类型(聚丙烯、玄武岩)、长度(3 mm, 6 mm, 9 mm)及掺量(0%, 0.1%, 0.4%, 0.7%, 1.0%)对材料7 d、28 d单轴抗压强度的影响，并结合X射线衍射(XRD)分析微观晶体结构演变，建立宏微观性能关联体系。结果表明：两种纤维均能显著提升材料抗压强度，聚丙烯纤维9 mm + 1.0%掺量为7 d最优配方，其强度0.97 MPa (较对照 + 94.0%)，为所有样品最高值，稳定性良好；聚丙烯纤维3 mm + 0.1%掺量，实测28 d强度0.87 MPa (较对照 + 93.3%)，是28 d强度最高的样品；XRD分析显示，纤维改性通过优化晶体结构支撑宏观强度提升：改性样品的核心水化产物C-S-H凝胶、Ca(OH)₂衍射峰强度显著提高，7 d、28 d龄期C-S-H衍射峰强度较对照组分别最高提升64.3%、73.4%；未水化水泥熟料C₃S衍射峰强度降低47.3%，表明纤维促进了水化反应与粉煤灰火山灰反应的充分进行。研究成果为煤层底板绿色注浆材料的配方优化与工程应用提供理论支撑。

Abstract: In order to solve the problems of insufficient strength and poor environmental protection of traditional cement-based materials in coal seam floor grouting engineering, two green fibers, polypropylene and basalt, were introduced to carry out modification research based on Grade II fly ash and P·O42.5 cement. By controlling the basic formula of fly ash content of 70%, water-solid ratio of 1:1 and water glass content of 3%, the effects of fiber type (polypropylene, basalt), length (3 mm, 6 mm, 9 mm) and content (0%, 0.1%, 0.4%, 0.7%, 1.0%) on the uniaxial compressive strength of the material at 7 and 28 days were systematically explored, and the evolution of microscopic crystal structure was analyzed by X-ray diffraction (XRD) to establish a macroscopic and microscopic performance correlation system. The results showed that the compressive strength of the two fibers could be significantly improved, and the optimal formulation of polypropylene fiber with 9 mm + 1.0% was the optimal formula for 7 days, and its strength was 0.97 MPa (+94.0% compared with the control), which was the highest value of all samples, and the stability was good. Polypropylene fiber was 3 mm + 0.1%, and the measured strength was 0.87 MPa (+93.3% compared with the control) at 28 days, which was the sample with the highest strength in 28 days. XRD analysis showed that fiber modification supported macroscopic strength improvement by optimizing the crystal structure: the intensity of the diffraction peaks of the core hydration products C-S-H gel and Ca (OH)₂ of the modified samples was significantly increased, and the intensity of C-S-H diffraction peaks at 7 and 28 days was the highest increased by 64.3% and 73.4% compared with the control group, respectively. The diffraction peak strength of C₃S in unhydrated cement clinker decreased by 47.3%, indicating that the fiber promoted the full reaction between hydration and fly ash volcanic ash. The research results provide theoretical support for the formulation optimization and engineering application of green grouting materials for coal seam floor.