Improving the stability of entrained air in self-compacting concrete by optimizing the mix viscosity and air entraining agent dosage
Improving the stability of entrained air in self-compacting concrete by optimizing the mix viscosity and air entraining agent dosage
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DOI：
10.1016/j.conbuildmat.2017.05.105
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发表时间：
2017-09
影响因子：
7.4
通讯作者：
Sovannsathya Rath;M. Ouchi;Nipat Puthipad;Anuwat Attachaiyawuth
中科院分区：
文献类型：
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作者：
Sovannsathya Rath;M. Ouchi;Nipat Puthipad;Anuwat Attachaiyawuth
为提高自密实混凝土（SCC）引气稳定性，研究了拌和工艺和引气剂对自密实混凝土中细、粗气泡引气量的影响。用空气空隙率分析仪（AVA）测定了新拌砂浆中气泡的尺寸分布。气泡的临界尺寸被定义为气泡体积随时间推移保持稳定的尺寸。根据较大气泡的体积与混合后两小时体积减少之间的相关性，发现以弦长定义的临界尺寸为500 μm。较低的砂浆粘度，获得使用的混合程序，其中水添加被分开，减少了细和粗气泡的总体积。随着AE剂量的增加，夹带的细气泡体积增加，粗气泡体积减少。细空气的上限体积被定义为较长混合时间夹带的细气泡的最大体积。该上限与AE剂量乘以作为粘度指数的砂浆的漏斗速度成比例。
The purpose of this study is to clarify the role of mixing procedure and air entraining agent (AE) on the entrained volume of fine and coarse air bubbles with the aim of improving the stability of entrained air in self-compacting concrete (SCC). Experiments were conducted in which the air bubbles size distribution of fresh mortars was measured with an air-void analyzer (AVA). Critical size of air bubble was defined as the size below which the bubble volume remains stable as time pass. This critical size, defined in terms of chord length, was found to be 500 μm from the correlation between the volume of larger bubbles and the reduction in volume two hours after mixing. A lower mortar viscosity, obtained using a mixing procedure in which water additions were divided, reduced the total volume of both fine and coarse air bubbles. With a higher dosage of AE, a higher volume of fine air bubbles and a lower volume of coarse air bubbles were entrained. An upper limit volume of fine air was defined as the maximum volume of fine air bubbles entrained with a longer mixing time. This upper limit is proportional to the AE dosage multiplied by the funnel speed of the mortar as an index of viscosity.