Flocculation in Cement Pastes Measured through Use of Laser Microscopy

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Title: Flocculation in Cement Pastes Measured through Use of Laser Microscopy

Author(s): R.P. Ferron, C. Negro, and S.P. Shah

Publication: Special Publication

Volume: 259

Issue:

Appears on pages(s): 107-120

Keywords: flocculation; FBRM; SCC; superplasticizer; viscosity-modifying agents

Date: 2/1/2009

Abstract:
Structural build-up that occurs during the induction period is of particular interest to users of self-consolidating concrete (SCC) since it can affect the workability of concrete. A novel experimental device based on scanning laser microscopy was used to directly monitor particle flocculation in SCC cement pastes. This is one of the few studies in which this experimental method has been used to study flocculation in concentrated suspensions. This paper discusses the results from a study that was carried out to investigate the flocculation and floc properties in SCC cement pastes. Results show that the floc network is immediately broken down by superplasticizers and that the rate of reflocculation decreases when the water-to-cement (w/c) ratio is decreased. An increase in w/c ratio resulted in a reduction in floc strength. Results show that viscosity modifying agents can induce flocculation due to different flocculation mechanisms.