铝粉掺量对微膨胀UHPC力学性能及工作性的影响

The Effect of Aluminum Powder Content on the Mechanical Properties and Workability of Micro Expanded UHPC

摘要: 基于装配式地下车站二次结构湿接缝的结构需求，研究铝粉掺量对于微膨胀UHPC的流动性、膨胀率、干密度、力学性能及气孔形态等性能的影响。在超高性能混凝土(UHPC)中掺入0.005%、0.010%和0.015%质量分数的铝粉。随着铝粉掺量的增大，微膨胀UHPC的流动性和膨胀率明显提升，干密度下降；微膨胀UHPC的抗压强度分别为123.97、121.00和109.60 MPa，下降率分别为12.58%、14.67%、22.71%，但对抗折强度的影响较小。当铝粉掺量为0.005%时，微膨胀UHPC能够在保证力学性能的情况下具有较为合适的膨胀率，适用于装配式地下车站二次结构湿接缝。

Abstract: This study aims to investigate the impact of aluminum powder content on the flowability, expansion rate, bulk density, mechanical properties, and pore morphology of micro-expansive Ultra-High Performance Concrete (UHPC) for wet joints in prefabricated underground stations. Aluminum powder was added to UHPC at mass fractions of 0.005%, 0.010%, and 0.015% respectively. With the increase in aluminum powder content, the flowability and expansion rate of micro-expansive UHPC significantly improved, while the bulk density decreased. The compressive strengths of micro-expansive UHPC were 123.97 MPa, 121.00 MPa, and 109.60 MPa respectively, with corresponding reduction rates of 12.58%, 14.67%, and 22.71%. However, the influence on flexural strength was relatively small. When the aluminum powder content was 0.005%, micro-expansive UHPC exhibited a suitable expansion rate while maintaining adequate mechanical performance, making it suitable for wet joints in prefabricated underground stations.