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500μm)而保留微小气泡(孔径小于200μm)。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[500,1000)μm的气泡含量降幅由31.0%增大至84.8%,孔径在[1000,2000)μm的气泡含量降幅由10.3%增大至36.4%。
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 sizeΦ>500μm)and retain tiny bubbles(Φ<200μm).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[500,1000)μm increases from 31.0%to 84.8%,and those with the pore size of[1000,2000)μm increases from 10.3%to 36.4%.
作者
金阳
潘俊铮
仲亮
韩咏书
周光照
高小建
JIN Yang;PAN Junzheng;ZHONG Liang;HAN Yongshu;ZHOU Guangzhao;GAO Xiaojian(China Construction Seventh Engineering Division Co.,Ltd.,Zhengzhou 450004,China;School of Civil Engineering,Harbin Institute of Technology,Harbin 150090,China)
出处
《硅酸盐通报》
CAS
北大核心
2023年第11期3866-3877,共12页
Bulletin of the Chinese Ceramic Society
基金
中建七局科技研发课题(CSCEC7bjt-2022-Z-2)
国家自然科学基金(U2106220)。
关键词
新拌混凝土
振捣
流变性
气泡结构
测试方法
引气剂
fresh concrete
vibration
rheology
air void structure
evaluating method
air-entrained agent
