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硅酸盐通报 ›› 2023, Vol. 42 ›› Issue (11): 3866-3877.

所属专题: 水泥混凝土

• 水泥混凝土 • 上一篇    下一篇

振捣作用下新拌混凝土流变性和气泡结构研究

金阳1, 潘俊铮2, 仲亮1, 韩咏书1, 周光照1, 高小建2   

  1. 1.中国建筑第七工程局有限公司,郑州 450004;
    2.哈尔滨工业大学土木工程学院,哈尔滨 150090
  • 收稿日期:2023-07-03 修订日期:2023-08-24 出版日期:2023-11-15 发布日期:2023-11-22
  • 通信作者: 高小建,博士,教授。E-mail:gaoxj@hit.edu.cn
  • 作者简介:金 阳(1988—),男,高级工程师。主要从事混凝土材料与结构方面的研究。E-mail:309094491@qq.com
  • 基金资助:
    中建七局科技研发课题(CSCEC7bjt-2022-Z-2);国家自然科学基金(U2106220)

Rheology and Air Void Structure of Fresh Concrete under Vibration

JIN Yang1, PAN Junzheng2, ZHONG Liang1, HAN Yongshu1, ZHOU Guangzhao1, GAO Xiaojian2   

  1. 1. China Construction Seventh Engineering Division Co., Ltd., Zhengzhou 450004, China;
    2. School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China
  • Received:2023-07-03 Revised:2023-08-24 Online:2023-11-15 Published:2023-11-22

摘要: 振捣是混凝土密实成型的重要手段,振捣效果直接决定了混凝土成型后的力学性能和耐久性能。本文提出了基于斯托克斯定律、适用于振捣作用下新拌混凝土流变性的测试和评价方法——拉球法,分析了静态下该方法与流变仪所测流变参数的相关性,论证了其评价新拌混凝土流变性的可靠性。结果表明,拉球法与流变仪所测塑性黏度和屈服应力具有良好的线性相关性。振捣可使近振源处浆体的黏性阻力降低90%以上,并且可以有效排出新拌砂浆中的较大气泡(孔径大于500 μm)而保留微小气泡(孔径小于200 μm)。高引气剂掺量下振捣排出较大气泡的作用效果更强,当引气剂掺量由0.015%增大至0.030%(质量分数)时,孔径在[500,1 000) μm 的气泡含量降幅由31.0%增大至84.8%,孔径在[1 000,2 000) μm的气泡含量降幅由10.3%增大至36.4%。

关键词: 新拌混凝土, 振捣, 流变性, 气泡结构, 测试方法, 引气剂

Abstract: Vibration is an essential mean of concrete compaction and forming. The effect of vibration directly determines the mechanical properties and durability of hardened concrete. Based on Stokes' law, this paper proposed a new method for measuring and evaluating the rheology of fresh concrete under vibration, namely, the pulling-ball method. The correlation between the rheological parameters obtained by this method and those obtained by the rheometer at static state was analyzed, demonstrating the pulling-ball method's reliability for evaluating the rheology of fresh concrete. The results show good linear correlations between the plastic viscosity and the yield stress obtained by the pulling-ball method and those obtained by the rheometer individually. Vibration can reduce the viscous drag force of cement mortar near the internal poker vibrator by more than 90% and effectively discharge large bubbles (pore size Φ>500 μm) and retain tiny bubbles (Φ<200 μm). Vibration substantially affects removing large bubbles with increasing air-entrained agent (AEA) content. When the AEA content roses from 0.015% to 0.030% (mass fraction), the decreasing of air void content with the pore size of [500,1 000) μm increases from 31.0% to 84.8%, and those with the pore size of [1 000,2 000) μm increases from 10.3% to 36.4%.

Key words: fresh concrete, vibration, rheology, air void structure, evaluating method, air-entrained agent

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