超高性能混凝土流变特性及其调控研究

为了实现超高性能混凝土(UHPC)流变特性的高效调控,采用膨润土作为辅助胶凝材料并对制备的UHPC进行了性能评估,包括UHPC浆体的流动度、静态屈服应力、动态屈服应力、塑性黏度和触变性,并系统分析了不同掺量的膨润土对UHPC浆体流变性能的影响。结果表明:随着膨润土掺量增加,UHPC浆体的流动度整体表现为下降趋势,下降幅度逐渐增大;当膨润土掺量由0%增加到15.0%(质量分数)时,UHPC浆体静态屈服应力、动态屈服应力和塑性黏度均显著增大,分别提高了约17.05倍、5.78倍和1.16倍;随着膨润土掺量增加,滞回环面积和触变指数增大,触变性得到明显改善。同时,掺入膨润土后仍然满足UHPC的优异力学性能要求。

Rheological Characteristics of Ultra-High Performance Concrete and Its Regulation

In order to achieve the efficient regulation of the rheological properties of ultra-high performance concrete (UHPC), bentonite was used as an auxiliary cementing material and the performances of the prepared UHPC were evaluated. The fluidity, static yield stress, dynamic yield stress, plastic viscosity and thixotropy of UHPC slurry were studied, and the effect of different bentonite content on the rheological properties of UHPC slurry was systematically analyzed. The results show that: the overall fluidity of UHPC slurry shows a downward trend, and the decline amplitude gradually increases with the increase of bentonite content. When the content of bentonite increases from 0% to 15.0% (mass fraction), the static yield stress, dynamic yield stress and plastic viscosity of UHPC slurry increase significantly, by about 17.05 times, 5.78 times and 1.16 times, respectively. The hysteresis loop area and thixotropy index increase with the increase of bentonite content, and the thixotropy is significantly improved. Meanwhile, UHPC with bentonite still meets the advanced mechanical properties of UHPC.