In-situ investigation of superplasticizers: From fluorescence microscopy to concrete rheology
In-situ investigation of superplasticizers: From fluorescence microscopy to concrete rheology
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DOI：
10.1016/j.cemconres.2018.08.011
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发表时间：
2018-11-01
影响因子：
11.4
通讯作者：
Middendorf, B.
中科院分区：
文献类型：
--
作者：
Arend, J.;Wetzel, A.;Middendorf, B.
具有高强度和耐久性的混凝土需要有机聚合物来获得均匀的混凝土混合物，这是由于低混合水量和高含量的具有大内表面的细填料。这些所谓的高效减水剂的基本工作机理在理论上得到了广泛的理解，但仍然存在不清楚的现象，如与某些添加剂的不相容性。本研究提供了一种新的方法来研究高效减水剂与矿物颗粒的相互作用。随着荧光显微镜的应用，它是可能的第一次本地化和量化的超增塑剂颗粒的吸附，并在测量过程中改变实验参数。该方法首次实现了高效减水剂与矿物表面相互作用的原位研究。在所示的荧光显微镜实验中，钙离子对于这些聚合物对矿物颗粒表面的必要吸附的重要作用是显而易见的。此外，取决于所用悬浮液中存在的钙离子浓度的吸附聚合物的检测量与各种矿物质的ζ电位的发展相关。最后，两种不同的高效减水剂的微观测量的吸附试验砂浆的流变性能之间的相关性成功。
Concretes with advanced strength and durability necessitates organic polymers to receive a homogeneous concrete mixture due to a low amount of mixing water and a high content of fine fillers with large inner surface. The basic working mechanisms of those so-called superplasticizers are widely understood in theory, but still there are unclear phenomena like incompatibilities with certain additives. This study presents a novel method to investigate the interaction of superplasticizers with mineral particles. With the application of fluorescence microscopy, it is possible for the first time to localize and quantify the adsorption of superplasticizers to particles and to vary experimental parameters during the measurement. The presented results prove this method, which enables first time to investigate the superplasticizer interaction with mineral surfaces in situ. The important role of calcium ions for the necessary adsorption of those polymers to mineral particle surfaces is obvious in the shown fluorescence microscopic experiment. Furthermore, the detected amount of adsorbed polymers depending in the concentration of calcium ions present in the used suspension correlates with the development of the zeta potential of various minerals. Finally, a correlation between the microscopically measured adsorption of two different superplasticizers to rheological properties of a test mortar succeeded.