Studying Admixtures with the 5C Rheometer


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Title: Studying Admixtures with the 5C Rheometer

Author(s): R.J. Flatt and I. Schober

Publication: Special Publication

Volume: 239


Appears on pages(s): 93-104

Keywords: admixtures; adsorption; rheology; superplasticizers

Date: 10/1/2006

Testing of admixtures performance is done routinely in industrial laboratories with spread tests in which a cylindrical mould is filled with cement paste and then lifted. The sample spreads and the measured diameter is used to infer the efficiency of the admixture. Recent results link this measurement quantitatively to yield stress. On the other hand, expressions for the dependence of yield stress on interparticle forces and volume fraction of cement have been proposed. In this paper, it is shown that the combination of both approaches brings new insights into the mechanisms by which admixtures modify the rheology of cementitious materials.