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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 > Tools > Frequently Asked Questions
Q. Are retarding admixtures reliable as to the time of setting? A. Yes, unless they are grossly overdosed. In addition to variation in the dosage of the retarding admixture and properties of the cement, initial and final times of setting of the concrete depend on the w/cm, temperature of the concrete, and ambient conditions. Changes in these conditions will alter time of setting with or without a retarding admixture. When other admixtures are used in combination with the retarding admixture, care should be exercised to avoid unexpected extension in time of setting. Large dosages of water reducing admixtures may also extend the setting times. Lowering the temperature of concrete and making use of some of the pozzolans also extend the time of setting (ACI 207.1R). References: SP-1(02); E4-12; ACI 212.3R-16; SP-288; ACI 207.1R-05; ASTM C494 Topics in Concrete: Admixture; Concrete Fundamentals; Hot Weather; Pozzolan
Q. Are retarding admixtures reliable as to the time of setting?
A. Yes, unless they are grossly overdosed. In addition to variation in the dosage of the retarding admixture and properties of the cement, initial and final times of setting of the concrete depend on the w/cm, temperature of the concrete, and ambient conditions. Changes in these conditions will alter time of setting with or without a retarding admixture. When other admixtures are used in combination with the retarding admixture, care should be exercised to avoid unexpected extension in time of setting. Large dosages of water reducing admixtures may also extend the setting times. Lowering the temperature of concrete and making use of some of the pozzolans also extend the time of setting (ACI 207.1R).
References: SP-1(02); E4-12; ACI 212.3R-16; SP-288; ACI 207.1R-05; ASTM C494
Topics in Concrete: Admixture; Concrete Fundamentals; Hot Weather; Pozzolan
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