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66. Influence of mineral and organic admixtures on the stability of cementitious pastes under flow



Title: 66. Influence of mineral and organic admixtures on the stability of cementitious pastes under flow
Author(s): J. Yammine, M. Chaouche, M. Moranville
Paper category : conference
Book title: 5th International RILEM Symposium on Self-Compacting Concrete
Editor(s): G. De Schutter and V. Boel
Print-ISBN: 978-2-35158-047-9
e-ISBN: 978-2-35158-088-2
Publisher: RILEM Publications SARL
Publication year: 2007
Pages: 443 - 448
Total Pages: 6
Nb references: 6
Language: English


Abstract: The influence of mineral fillers and high water reducing admixtures (HWRAs) on the stability of cementitious pastes relative to phase separation is considered using the squeeze test. The investigation is undertaken at the cement paste scale.
The fresh pastes are squeezed out at controlled speeds between two parallel plates set on a compression machine. Since cementitious pastes are power-law fluids with a yield stress, the normal force is expected to follow the Scott’s law under lubricating homogeneous conditions.
At sufficiently high speeds and/or gaps, the behaviour of the squeeze force is found to be indeed in agreement with the prediction of the Scott’s law. On the contrary, at low speeds and/or gaps it is observed a significant deviation from the Scott’s law, which may be attributed to the filtration of the finest phase through the porous media made up by the coarsest grains of the paste. The squeeze test can be then used as a tool to determine flow conditions under which phase separation and eventually blockage may occur. It is found that the microfillers and HWRAs significantly improve the stability of pastes, that is attributed to the decrease of the paste’s permeability due to the filling ability of microfillers and the deflocculation of cement particles by the HWRAs.


Online publication: 2009-06-16
Publication type : full_text
Public price (Euros): 0.00


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