Su Yonghua, Luo Biao, Luo Zhengdong, Huang He, Li Jianbao, Wang Dehui
College of Civil Engineering, Hunan University, Changsha 410082, China.
College of Civil Engineering and Mechanics, Xiangtan University, Xiangtan 411105, China.
Materials (Basel). 2021 Dec 26;15(1):159. doi: 10.3390/ma15010159.
The preparation of ultra-high-performance concrete (UHPC) with both high-early-strength and good workability contributes to further promotion of its development and application. This study investigated the effects of different accelerators (SM, alkaline powder accelerator; SF, alkaline powder accelerator containing fluorine; and AF, alkali-free liquid accelerator containing fluorine) on the workability and strength properties of UHPC. The microstructure of UHPC was also characterized by using XRD and SEM. Several dosage levels of accelerators (2%, 4%, 6%, and 8% by mass) were selected. The results indicate that the setting time and fluidity of UHPC are gradually decreased with an increase in accelerators dosage. Compared with fluorine-containing SF/AF, fluorine-free SM evidently facilitates UHPC early strength gain speed. However, the fluorine-containing accelerators have a higher 28 d strength ratio, especially AF. The maximum compressive and flexural strength ratios are obtained at a dosage of 6%, which are 95.5% and 98.3%, respectively. XRD and SEM tests further reveal the effect of different accelerators on the macroscopic properties of UHPC from the micro level.
制备兼具高早期强度和良好工作性的超高性能混凝土（UHPC）有助于进一步推动其发展与应用。本研究考察了不同促凝剂（SM，碱性粉末促凝剂；SF，含氟碱性粉末促凝剂；AF，含氟无碱液体促凝剂）对UHPC工作性和强度性能的影响。还通过XRD和SEM对UHPC的微观结构进行了表征。选择了几种促凝剂掺量水平（质量分数2%、4%、6%和8%）。结果表明，随着促凝剂掺量的增加，UHPC的凝结时间和流动性逐渐降低。与含氟的SF/AF相比，无氟的SM明显促进了UHPC早期强度增长速度。然而，含氟促凝剂具有更高的28天强度比，尤其是AF。在掺量为6%时获得最大抗压和抗折强度比，分别为95.5%和98.3%。XRD和SEM测试进一步从微观层面揭示了不同促凝剂对UHPC宏观性能的影响。
