Datum
2020-02-27Schlagwort
660 Chemische Verfahrenstechnik, Technische Chemie Ultrahochfester BetonBetonverflüssigerAdsorptionVerzögerungFluoreszenzmikroskopieMetadata
Zur Langanzeige
Aufsatz
Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC
Zusammenfassung
The adsorption of superplasticizer molecules to particle surfaces in cementitious systems is a very important aspect for the desired liquefaction of pastes and concretes. This way, the comb shaped polymers shield attractive forces between the particles and induce a well-dispersed, homogeneous suspension. These admixtures allow the usage of fine fillers even in combination with low amounts of mixing water, and thus, are the basis for modern high performance concretes. However, the adsorption does not cause beneficial effects only: The polymer covered particle surfaces, especially clinker, are hindered to interact with water, thus hydration is retarded. This is the reason for lower early strength and is very disadvantageous for certain applications. Today it is known that the molecular structure of the polymers, for instance the chain length and charge density, affects the retardation strongly. The complexity and diversity of cementitious systems is the main reason why research in this field is quite empiric and time as well as cost intensive. To investigate the adsorption of superplasticizers in various systems in-situ, a fluorescence microscopic approach was applied: By staining the polymers with fluorescent dye they become localizable and the adsorption quantifiable. This work shows the influence of molecular structure to adsorption characteristic of different polymers and the correlation to the retarding effect of superplasticizers, especially concerning the presence of silica fume, which is indispensable for ultra-high performance concrete (UHPC).
Zitierform
In: Materials Volume 13 / Issue 5 (2020-02-27) eissn:1996-1944Zitieren
@article{doi:10.17170/kobra-202108044482,
author={Arend, Johannes and Wetzel, Alexander and Middendorf, Bernhard},
title={Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC},
journal={Materials},
year={2020}
}
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2021-08-04T11:07:52Z 2021-08-04T11:07:52Z 2020-02-27 doi:10.17170/kobra-202108044482 http://hdl.handle.net/123456789/13073 eng Namensnennung 4.0 International http://creativecommons.org/licenses/by/4.0/ UHPC superplasticizer retardation fluorescence microscopy 660 Fluorescence Microscopic Investigations of the Retarding Effect of Superplasticizers in Cementitious Systems of UHPC Aufsatz The adsorption of superplasticizer molecules to particle surfaces in cementitious systems is a very important aspect for the desired liquefaction of pastes and concretes. This way, the comb shaped polymers shield attractive forces between the particles and induce a well-dispersed, homogeneous suspension. These admixtures allow the usage of fine fillers even in combination with low amounts of mixing water, and thus, are the basis for modern high performance concretes. However, the adsorption does not cause beneficial effects only: The polymer covered particle surfaces, especially clinker, are hindered to interact with water, thus hydration is retarded. This is the reason for lower early strength and is very disadvantageous for certain applications. Today it is known that the molecular structure of the polymers, for instance the chain length and charge density, affects the retardation strongly. The complexity and diversity of cementitious systems is the main reason why research in this field is quite empiric and time as well as cost intensive. To investigate the adsorption of superplasticizers in various systems in-situ, a fluorescence microscopic approach was applied: By staining the polymers with fluorescent dye they become localizable and the adsorption quantifiable. This work shows the influence of molecular structure to adsorption characteristic of different polymers and the correlation to the retarding effect of superplasticizers, especially concerning the presence of silica fume, which is indispensable for ultra-high performance concrete (UHPC). open access Arend, Johannes Wetzel, Alexander Middendorf, Bernhard doi:10.3390/ma13051057 Ultrahochfester Beton Betonverflüssiger Adsorption Verzögerung Fluoreszenzmikroskopie publishedVersion eissn:1996-1944 Issue 5 Materials Volume 13 false 1057
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