Modelling of the Flocculated Polydisperse Microstructure of Fresh Cement Paste
Open access
Date
2023Type
- Conference Paper
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yes
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Abstract
Granular materials present in nature are commonly polydisperse, featuring an inconsistent grain size distribution. This characteristic directly affects particle packing, and consequently influences attributes such as maximal packing fraction, bulk density, rheology, and derived properties. For cement, this has direct consequences as polydispersity, among other factors, influences considerably the rheology and concurrent microstructural build-up in the fresh paste. Previous studies on polydispersity in granular systems considered only mechanical contact forces among particles, but omitted non-contact colloidal interactions, which dominate the microstructure in cement paste. Therein, the flocculation of particles, caused by these interactions, creates a percolated network, which is strongly affected by the polydispersity, but is not fully understood yet. In this paper, we show how flocculation affects the microstructural build up and the resulting rheological and mechanical properties of fresh cement paste. By accounting for flocculation in our numerical modelling, we can produce statistically representative microstructures, which maintain physically consistent rheological properties. We observed that the mechanical properties of percolated particle networks due to flocculation depend on their packing fraction and size distribution. A higher packing ratio offers a higher shear resistance of the fresh paste. Accounting for polydispersity in flocculated build-up does influence the shear resistance, as opposed to a granular system with only contact forces, where the shear strength is independent of grain size span. Our model provides insight into the micro-mechanical origin of the rheology of fresh cement paste, contributing to a better balance between workability and buildability in early stage, and to a better understanding reignited for the design of new concrete mixtures for digital fabrication. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000636045Publication status
publishedBook title
Further Reduction of CO2-Emissions and Circularity in the Cement and Concrete Industry, 16th International Congress on the Chemistry of Cement 2023 - ICCC2023Volume
Pages / Article No.
Publisher
Thailand Concrete AssociationEvent
Subject
Polydispersity; Flocculation; Fresh cement paste; Colloidal interaction; Granular systemOrganisational unit
09650 - Kammer, David / Kammer, David
09650 - Kammer, David / Kammer, David
Funding
200343 - Early structural build-up in accelerated cement (SNF)
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