Rheology of fresh cement pastes modified with nanoclay-coated cements
Rheology of fresh cement pastes modified with nanoclay-coated cements
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DOI：
10.1016/j.cemconcomp.2021.104301
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发表时间：
2021-10-25
影响因子：
10.5
通讯作者：
Kawashima, Shiho
中科院分区：
文献类型：
--
作者：
Douba, AlaEddin;Ma, Siwei;Kawashima, Shiho
纳米粘土（NC）可以作为新混凝土的触变性改性剂，并显示出满足3D混凝土打印流变要求的潜力。在这里，我们提出了一种干法分散技术，生产NC涂层水泥和比较传统的分散方法。通过剪切流变学、扫描电子显微镜和等温量热法测试了掺入NC的浆料。干分散被认为是最有效的方法，其中将4.0重量%的NC增加了静态屈服应力和储能模量的水泥浆的1500%和550%，分别与90%的粘度的最小增加。小振幅振荡剪切和等温量热法的结果表明，NC可以提高新鲜状态硬化通过播种，虽然剪切流变学的煤油基水泥系统的结果表明，NC的静态屈服应力的增加主要是由于离子力。最后，我们将讨论如何将这些特性转化为高可构建性和稳定的层沉积。
Nanoclays (NC) can serve as thixotropy modifiers for fresh concretes, and show potential to meet the rheological demands of 3D concrete printing. Here, we propose a dry dispersion technique that produces NC-coated cement and compare to conventional methods of dispersion. Pastes incorporating NC were tested via shear rheology, scanning electron microscopy, and isothermal calorimetry. Dry dispersion was found to be the most effective method, where incorporating 4.0 wt% NC increased the static yield stress and storage modulus of cement paste by 1500% and 550%, respectively, with a minimal increase in viscosity of 90%. Results of small amplitude oscillatory shear and isothermal calorimetry indicated NC can enhance fresh-state stiffening through seeding, although shear rheology results of kerosene-based cement systems indicated the increase in static yield stress by NC is mainly due to ionic forces. Finally, we discuss how these properties translate to high buildability and stable layer deposition.