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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Effect of Chemical Structure on Fluidizing Mechanism of Concrete Superplasticizer Containing Polyethylene Oxide Graft Chains
Author(s): M. Kinoshita, T. Nawa, M. lida, and H. lchiboji
Publication: Special Publication
Appears on pages(s): 163-180
Keywords: adsorption; mixing time; superplasticizer
Abstract:Methacrylic graft copolymers (hereafter referred to as graft copolymers) were synthesized to investigate the effects of chemical structures on the fluidizing mechanism of concrete superplasticizer containing polyethylene oxide graft chains. The cement-dispersing performance of graft copolymers is strongly affected by the length of the polyoxyethylene graft chains and is governed more by steric repulsion than electrostatic repulsion. Graft copolymers having longer graft chains and a relatively short backbone required a shorter mixing time and exhibited excellent fluidity immediately after mixing. Conversely, the fluidity-retaining capability was lower. The authors therefore synthesized a graft copolymer having different graft chain lengths to attain the high fluidity and fluidity-retaining capability, and investigated its properties. As a result, the graft copolymer having graft chains with different lengths was found to satisfy both performance requirements for fluidity and fluidity retention. Moreover, this copolymer was found to be adsorbed less onto cement particles, resulting in a low set-retarding effect. It was also confirmed that the cement-dispersing capability of graft copolymers varies depending on the cement type. Belite-rich low-heat portland cement with a low C3A content leads to high fluidity with a much lower dosage of graft copolymers than normal portland cement. These properties of graft copolymers and cement suggest their promising applicability to production of high performance concrete.
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