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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: Working Mechanisms of Air-Entraining Admixtures and Their Subsequent Activation Potential
Author(s): Eberhard Eickschen
Publication: Special Publication
Appears on pages(s): 1-11
Keywords: air-entraining agent; air void; alkylsulfate; alkylsulfonate; alkylpolyglycolethersulfate; concrete; mixing time; precipitation; vinsol resin.
Abstract:From some job sites it was reported that the air void content of the hardened concrete was higher than that of the fresh concrete. Investigations with commercial air-entrainers based on synthetic and natural active agents showed that a substantial increase in air content can occur only if the fresh concrete is supplied with air-entrainer that is insuffi¬cient activated. The air void content may increase if mixing energy is subsequently applied during placement or transport. The air void formation was studied as a function of the type and quantity of the admixture added and of the mixing time. Furthermore, the precipitation of admixtures in calcium hydroxide was investigated. A subsequent increase in air content is to be expected only with admixtures based on synthetic active agents due to their better solubility in the pore solution. The knowledge of the working mechanisms allows giving recommendations for practice to avoid an increase in the air content.
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