Email Address is required Invalid Email Address
In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Learn More
Become an ACI Member
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.
Staff Directory
ACI World Headquarters 38800 Country Club Dr. Farmington Hills, MI 48331-3439 USA Phone: 1.248.848.3800 Fax: 1.248.848.3701
ACI Middle East Regional Office Second Floor, Office #207 The Offices 2 Building, One Central Dubai World Trade Center Complex Dubai, UAE Phone: +971.4.516.3208 & 3209
ACI Resource Center Southern California Midwest Mid Atlantic
Feedback via Email Phone: 1.248.848.3800
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
Search other resources on the ACI website for answers to technical questions