Multifunctional Chemical Admixture to Reduce Quality Control Requirements of Self-Consolidated Concrete

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Title: Multifunctional Chemical Admixture to Reduce Quality Control Requirements of Self-Consolidated Concrete

Author(s): A.A. Jeknavorian, E. Koehler, A. Abelleira, D. Geary, and R. Cook

Publication: Special Publication

Volume: 262

Issue:

Appears on pages(s): 35-46

Keywords: dynamic and static yield stress; moisture tolerance; rheology; self-consolidating concrete (SCC); slump flow; superplasticizers; thixotropy; viscosity; workability box.

Date: 10/1/2009

Abstract:
Self-consolidated concrete (SCC) is increasingly being used for both precast and ready mixed concrete applications. For ready mixed concrete, slump flow retention becomes a concern when the concrete is transported for long distance, and when delays in placing the concrete occur due to unexpected traffic problems or incomplete jobsite preparations. In this study, the performance of a special multifunctional superplasticizer is discussed that can enable SCC mixtures to have slump flow retention up to two hours without any significant extended setting properties and delay in strength gain. Furthermore, during the period of extended slump-flow, the SCC demonstrates rheological properties adequate to ensure segregation resistance once the concrete has been placed, as well as good moisture tolerance. This capability provided by the special superplasticizer formulation is expected to significantly reduce quality control operations and facilitate the successful production and placement of self-consolidating ready mixed concrete by imparting an appropriate amount of thixotropy to the SCC mixture without compromising suitable flow properties.