In-situ characterization of fresh-state microstructure in cementitious materials: impact of aggregation kinetics

Author(s): R. Ferron, S. Shah, C. Negro
Paper category: Symposium
Book title: 3rd International RILEM Symposium on Rheology of Cement Suspensions such as Fresh Concrete
Editor(s): O.H. Wallevik, S. Kubens, S. Oesterheld
ISBN: 978-2-35158-091-2
e-ISBN: 978-2-35158-092-9
Pages: 55 - 61
Total Pages: 7
Language: English

Abstract: 
The rheological properties of concrete are impacted by the degree of structure within the paste matrix, which in turn is governed by the aggregation mechanisms. In cementitious suspensions, direct measurement of particle aggregation is difficult due to the high solids concentration, high opaqueness and inherent aging (e.g. hydration) of the system. Hence, there is a lack of fundamental knowledge about the internal structure of cement paste and its role on the rheological behavior. An advanced experimental method that enables in-situ particle size measurements was used to characterize the fresh state microstructure. A kinetics-based model was used to determine the aggregation mechanisms (i.e. floc strength, rate of aggregation, rate of disaggregation). Results indicate that when the aggregation process dominates, there is a limiting criterion for particle aggregation during the early stages of the induction period under shear. The results indicate that the floc strength is inversely proportional to floc size.

Online publication: 2009
Publication Type: full_text
Public price (Euros): 0.00