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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: Progress in Understanding the Functional Properties of Superplasticizers in Fresh Concrete
Author(s): C. Jolicoeur, P. C. Nkinamubanzi, M. A. Simard, and M. Piotte
Publication: Special Publication
Appears on pages(s): 63-88
Keywords: adsorption; calorimeters; cement pastes; cements; heat of hydration; mineral admixtures; rheological properties; slurries; superplasticizers; Materials Research
Abstract:A variety of new literature and data on the properties of cement pastes and concentrated slurries of various types of mineral particles are examined to elucidate the origin of the fluidification of cement pastes by superplasticizers. The influence of sodium poly-¯-naphthalene sulfonate superplasticizers (NaPNS) of different molecular weights on the rheological properties of pastes and on the early heat of hydration of cement, together with results from other physicochemical measurements (adsorption, zeta potential), suggests that the unique fluidification effect of these admixtures depends on at least four distinct phenomena. With reference to fluidification of slurries of "inert" minerals, the superplasticizer effect in concrete can be understood in terms of nonspecific (physical) and specific (chemical) effects. The "physical" effects comprise: adsorption of the superplasticizer molecules by van der Waals and electrostatic forces (direct or assisted by cations); surface charging that induces long-range interparticle repulsive forces; steric hindrance between adsorbed polymer molecules on neighboring particles, leading to added short-range repulsive forces. The "chemical" effect involves a reaction of the PNS superplasticizer molecules with the most reactive sites of cement particles (particularly C 3A), substantially reducing the initial surface hydration rate. This description is largely based on data relevant to PNS-type superplasticizers, but with proper allowance for specific chemical effects, it should also be valid for other types of superplasticizer.
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