Overview of Rheological Parameters Affecting Stability of SCC

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Title: Overview of Rheological Parameters Affecting Stability of SCC

Author(s): Ya Peng, Stefan Jacobsen, Klaartje De Weerdt, Bard Pedersen, and Britt Blom Marstrander

Publication: Special Publication

Volume: 288

Issue:

Appears on pages(s): 1-16

Keywords: stability, sedimentation, segregation, bleeding, chemical admix¬ture, fillers

Date: 9/14/2012

Abstract:
The improved fluidity of self-consolidating concrete by using chemical admix¬tures sometimes causes stability problems. In this paper some fundamentals of particle settling theory, such as Stokes’ law, are used to investigate particle sedimentation. Some preliminary calculations of stresses from particles (>0.125 mm [4.93E-4 in.]) on matrix (liquid and powder < 0.125 mm) with viscous fluid properties, indicate that yield stress is more important than plastic viscosity for the stability of aggregates when settling in matrix. The Kozeny-Carman equation (KCE) is used to analyse bleeding rate of fresh matrix with three main factors involved: solid fraction, specific surface area and liquid viscosity. Different stabilizing mechanisms of viscosity modifying agents (VMA) and fillers are also reviewed. Finally a settlement model is set up for further investigation.