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61. Field measurements of SCC rheology and formwork pressures



Title: 61. Field measurements of SCC rheology and formwork pressures
Author(s): E.P. Koehler, L. Keller, N.J. Gardner
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: 411 - 416
Total Pages: 6
Language: English


Abstract: Field measurements were made of the rheology and formwork pressures of 3 separate selfconsolidating concrete (SCC) mixtures. Rheology measurements were made directly with the ICAR rheometer-a portable, vane-type rheometer-and indirectly with the slump flow test.
An attempt was made to match the shear history of the concrete used for rheological measurements to that of the concrete in the forms. The maximum, recorded, lateral formwork pressures varied from 28% to 98% of hydrostatic pressure. The rate of increase of the static yield stress-measured either with the rheometer or slump flow test-was found to be important for evaluating formwork pressure. This rate of increase was affected by the loss of superplasticizer efficacy, hydration, and thixotropy. Concrete rheological properties were shown to be highly influenced by changes in mixture proportions, especially changes in admixture type and dosage. Increasing yield stress retention by varying the types and dosages of superplasticizer and retarder were beneficial for lengthening transport and placing times but resulted in significantly higher formwork pressures.


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