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In-situ investigation of superplasticizers: From fluorescence microscopy to concrete rheology
Cement and Concrete Research ( IF 10.9 ) Pub Date : 2018-11-01 , DOI: 10.1016/j.cemconres.2018.08.011
J. Arend , A. Wetzel , B. Middendorf

Abstract 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.

中文翻译:

超塑化剂的原位研究:从荧光显微镜到混凝土流变学

摘要 具有先进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,因为混合水量少,内表面大的细填料含量高。那些所谓的超塑化剂的基本工作机制在理论上已经被广泛理解,但仍然存在与某些添加剂不相容等不清楚的现象。本研究提出了一种研究超塑化剂与矿物颗粒相互作用的新方法。随着荧光显微镜的应用,首次有可能对超塑化剂对颗粒的吸附进行定位和量化,并在测量过程中改变实验参数。所呈现的结果证明了这种方法,这使首次能够原位研究超塑化剂与矿物表面的相互作用。在所示的荧光显微实验中,钙离子对于将这些聚合物必要地吸附到矿物颗粒表面的重要作用是显而易见的。此外,根据所用悬浮液中存在的钙离子浓度检测到的吸附聚合物量与各种矿物质的 zeta 电位的发展相关。最后,两种不同减水剂的微观测量吸附与测试砂浆的流变特性之间的相关性成功。根据所用悬浮液中存在的钙离子浓度,检测到的吸附聚合物量与各种矿物质的 zeta 电位的发展相关。最后,两种不同减水剂的微观测量吸附与测试砂浆的流变特性之间的相关性成功。根据所用悬浮液中存在的钙离子浓度,检测到的吸附聚合物量与各种矿物质的 zeta 电位的发展相关。最后,两种不同减水剂的微观测量吸附与测试砂浆的流变特性之间的相关性成功。
更新日期:2018-11-01
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