Abstract:

Aiming at the problems of poor casting ability, long setting time and low early strength of traditional cement grouting materials, a new PPF reinforced superfine cement-based grouting material (SPGM) was obtained by using superfine Portland cement as cementing material, accelerating agent, expanding agent and water reducing agent as admixtures, and in cooperation with polypropylene fiber (PPF) toughening method. The effects of PPF length on mechanical properties, fluidity, bleeding, setting time and volume shrinkage behavior of SPGM were investigated by various characterization methods, and the enhancement mechanism was revealed. The results showed that the modification of PPF significantly reduced the fluidity and bleeding rate of SPGM, promoted hydration reaction and shortened setting time of the slurry. When the length of PPF was 2—3mm, the PPF reinforced SPGM stone bodies indicated optimal mechanical properties. Its compressive strength and flexural strength at 28 days were 64.20MPa and 12.35MPa, respectively. And it achieved good micro-expansion characteristics. XRD, FTIR and SEM confirmed that the length of PPF affected the specific surface area and distribution state in SPGM. PPF with appropriate length can effectively improve the density of the stone body, playing the role of micro-anchor cable and bridge. The results of this study provided a new approach for the development of high-quality cementitious grouting materials.

Key words: grouting material, superfine portland cement, polypropylene fiber, mechanical property, size effect

摘要：

针对传统水泥注浆材料可注性差、凝结时间长且早期强度低等问题，采用超细硅酸盐水泥为胶凝材料，速凝剂、膨胀剂、减水剂作外加剂，协同聚丙烯纤维（PPF）增韧方法，获得了一种新型PPF增强超细水泥基注浆材料（SPGM）。通过多种表征手段，探究PPF长度对SPGM的力学性能、流动度、泌水性、凝结时间、体积收缩行为的影响规律，并揭示了其增强机制。结果表明，PPF的改性可显著降低SPGM的流动度与泌水率，并促进水化反应，缩短浆液凝结时间。当PPF长度为2~3mm时，PPF增强SPGM结石体显示了最佳的力学性能，28天抗压强度和抗折强度分别达64.20MPa和12.35MPa，且实现良好微膨胀特性。X射线衍射、傅里叶变换红外光谱及扫描电子显微镜等表征证实了PPF长度会影响其在SPGM内部的比表面积与分布状态，适宜长度的PPF能有效提升结石体致密性，更好地发挥微锚索、桥连作用。该研究结果为高质量水泥基注浆材料研发提供了新方法。

关键词: 注浆材料, 超细硅酸盐水泥, 聚丙烯纤维, 力学性能, 尺寸效应