Understanding the Role of Quartz Powder Content and Fineness on the Micro-Structure and Mechanical Performance of UHPC

作者：Jianguang Xu, Yongsheng Li, Yue Huang, Guojian Yuan, Zhonglu Cao, W.F. Zhang, Heping Zheng, Yun Zang, Xingtai Mao, Mengmeng Li · 发表于：Buildings · 年份：2025 · DOI：10.3390/buildings15091513 · 被引用次数：6 · 研究领域：Advanced ceramic materials synthesis、Advanced materials and composites、Powder Metallurgy Techniques and Materials

To enhance the microstructure and mechanical properties and to optimize the formulations of high-strength and high-flow ultra-high-performance concrete (UHPC), the effects of different quartz powder contents, fineness, and curing temperatures of UHPC were systematically studied. It was hypothesized that using the appropriate content and fineness of quartz powder can improve the microstructure of UHPC and, thus, improve its mechanical properties, especially at higher curing temperatures. To test this hypothesis, the flowability, compressive strength, flexural strength, and tensile strength of UHPC mixtures with different quartz powder dosages (0%, 15%, 30%) and fineness (4 µm, 8 µm), cured at 20 °C, 45 °C, and 90 °C, were investigated. The results indicate that as the dosage of quartz powder increases and the particle size decreases, the flowability of UHPC decreases. The compressive strength of UHPC first increases and then decreases with an increase in quartz powder dosage. Finer quartz powder usage considerably enhances packing density and pore structure. When the content of quartz powder is 15%, UHPC achieves optimal mechanical properties and pore structure, showing an improvement of 3.6% to 14.4% compared to UHPC with a coarse particle size. Additionally, an increase in curing temperature leads to the consistent growth of the compressive strength of UHPC. Under 90 °C steam curing, UHPC incorporating 15% fine quartz powder (4 μm) achieved a peak compressive strength of 182...