Thixotropy-enhancing agent - A key component to reduce formwork pressure of self-consolidating concrete

Title: Thixotropy-enhancing agent - A key component to reduce formwork pressure of self-consolidating concrete
Author(s): K. Khayat
Paper category : conference
Book title: SCC'2005-China: 1st International Symposium on Design, Performance and Use of Self-Consolidating Concrete
Editor(s): Zhiwu Yu, Caijun Shi, Kamal Henri Khayat and Youjun Xie
Print-ISBN: 2-912143-61-6
e-ISBN: 2912143624
Publisher: RILEM Publications SARL
Publication year: 2005
Pages: 3 - 16
Total Pages: 14
Nb references: 6
Language: English

Abstract: A comprehensive research program was undertaken to evaluate the effect of concentration and type of thickening agents on the variations in lateral pressure that can be developed by self-consolidating concrete (SCC). Three conventional viscosity-enhancing agents (VEA), including a liquid polysaccharide, a powder polysaccharide, and a cellulose-based VEA as well a thixotropy-enhancing agent (TEA) were tested. All mixtures had similar initial slump flow of 650 ± 15 mm. The concrete was cast in an experimental column measuring 2800 mm in height to monitor variations in lateral pressure using a series of pressure sensors. Irrespective of the thickener in use, the incorporation of VEA or TEA at low concentration is shown to increase the rate of pressure drop with time compared to reference mixtures made without any thickener. Further increase in the concentration of conventional VEA can lead to reduced rate of pressure drop given the increase demand in high-range water-reducing admixture (HRWRA), which enhances fluidity retention. Unlike conventional VEA, the increase in TEA content decreases the initial maximum pressure as well as the rate of pressure drop. Combination of powder polysaccharide or cellulose-based VEA with TEA at low concentration was found to reduce the maximum lateral pressure and increase the rate of pressure drop compared to mixtures SCC containing VEA only at similar concentration. The incorporation of VEA/TEA combination resulted also in better fluidity retention.

Online publication: 2005-04-11
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143624.001