The dispersion characteristics of silica fume are pivotal factors influencing the rheological properties, mechanical properties, and durability of cement-based materials. This study investigated the dispersion behavior of different types of silica fume including highly densified silica fume (HDSF), moderately densified silica fume (MDSF), and raw silica fume (RSF) in water and cement paste filtrate mediums. Optical microscopy (OM) was utilized to monitor the silica fume agglomerations in suspensions, and scanning electron microscopy (SEM) was employed to observe the agglomerates in hardened ultra-high performance concrete (UHPC) containing 25 wt% silica fume. The results revealed that RSF, MDSF, and HDSF have similar particle size distributions in water and cement paste filtrate, with D values of 10.9 μm, 15.0 μm, and 112.2 μm, respectively. The agglomeration degree of silica fume is virtually unaffected by superplasticizer. Additionally, the effects of dispersion methods (i.e., ultrasonic, aerodynamic, and aggregate premixing) on silica fume dispersions were also investigated. It was shown that the aerodynamic dispersion method significantly reduced silica fume agglomeration, and adequate ultrasonic treatment almost eliminated physical agglomeration. By contrast, premixing silica fume with aggregates and steel fibers partially mitigated agglomeration. This study provides a theoretical foundation and technical guidance for the effective utilization of different types of silica fume in concrete applications.

中文翻译：

---

硅粉在水泥悬浮液中的分散行为


硅粉的分散特性是影响水泥基材料流变性能、力学性能和耐久性能的关键因素。本研究研究了不同类型硅粉（包括高致密硅粉（HDSF）、中致密硅粉（MDSF）和粗硅粉（RSF））在水和水泥浆滤液介质中的分散行为。利用光学显微镜 (OM) 监测悬浮液中的硅粉团聚体，并利用扫描电子显微镜 (SEM) 观察含有 25 wt% 硅粉的硬化超高性能混凝土 (UHPC) 中的团聚体。结果表明，RSF、MDSF 和 HDSF 在水和水泥浆滤液中具有相似的粒径分布，D 值分别为 10.9 μm、15.0 μm 和 112.2 μm。硅粉的团聚程度几乎不受高效减水剂的影响。此外，还研究了分散方法（即超声波、空气动力学和骨料预混合）对硅粉分散体的影响。结果表明，空气动力分散法显着减少了硅粉的团聚，而充分的超声波处理几乎消除了物理团聚。相比之下，将硅粉与骨料和钢纤维预混合部分减轻了团聚。该研究为不同类型硅粉在混凝土应用中的有效利用提供了理论基础和技术指导。