Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Role of steric hindrance in the performance of superplasticizers for concrete
Interparticle potential energy calculations were performed to investigate the mechanisms by which a new class of concrete admixtures, generally referenced as poly(carboxylic acid)-type (PC) superplasticizers, which aid in dispersing cement particles, are formed. These calculations consisted of long-range Van der Waals, electrostatic, and steric interactions. The repulsive potential that resulted from electrostatic interactions was negligible, which would allow cement particles to flocculate in the absence of steric contributions. A model was developed to describe the adsorption behavior of these superplasticizers, which consisted of grafted polyethylene oxide (PEO) chains on a PC backbone on cement surfaces. Using this adsorption mode, the influence of the length of the PEO molecular chain and the density per unit area on the steric contribution was quantified. Steric hindrance effects were the dominant stabilizing mechanism in this system. As expected, enhanced stability was observed with increasing adlayer thickness (and/or density). The results of this study may be useful in designing the molecular structure of this new and important class of dispersion aids for cement-based systems.
Role of steric hindrance in the performance of superplasticizers for concrete
Interparticle potential energy calculations were performed to investigate the mechanisms by which a new class of concrete admixtures, generally referenced as poly(carboxylic acid)-type (PC) superplasticizers, which aid in dispersing cement particles, are formed. These calculations consisted of long-range Van der Waals, electrostatic, and steric interactions. The repulsive potential that resulted from electrostatic interactions was negligible, which would allow cement particles to flocculate in the absence of steric contributions. A model was developed to describe the adsorption behavior of these superplasticizers, which consisted of grafted polyethylene oxide (PEO) chains on a PC backbone on cement surfaces. Using this adsorption mode, the influence of the length of the PEO molecular chain and the density per unit area on the steric contribution was quantified. Steric hindrance effects were the dominant stabilizing mechanism in this system. As expected, enhanced stability was observed with increasing adlayer thickness (and/or density). The results of this study may be useful in designing the molecular structure of this new and important class of dispersion aids for cement-based systems.
Role of steric hindrance in the performance of superplasticizers for concrete
Die Rolle der steroiden Barriere für die Wirksamkeit von Superplastifizierern für Beton
Yoshioka, Kazuhiro (Autor:in) / Sakai, Etsuo (Autor:in) / Daimon, Masaki (Autor:in) / Kitahara, Ayao (Autor:in)
Journal of the American Ceramic Society ; 80 ; 2667-2671
1997
5 Seiten, 8 Bilder, 3 Tabellen, 16 Quellen
Aufsatz (Zeitschrift)
Englisch
Beton , plastische Masse , Kristallkorn , Polymer , Ausflocken , Adsorption , Stabilisierung , Dispersion , Modell
| Elsevier | 1980
| TIBKAT | 1979
| NTIS | 1979
Improved Superplasticizers for High Performance Concrete
| British Library Conference Proceedings | 2003
Role of Superplasticizers and Slag for Producing High Performance Concrete
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