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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. How is workability measured and specified? A. The customary measure of workability is slump. ASTM C143 covers the determination of slump. The lowest acceptable slump is normally selected in preference to high slump due to a low w/cm and low amount of cementitious material, which are desirable; it also means less likelihood of segregation. The use of water-reducing admixtures, however, enables the preparation of concretes with a low w/cm and high slump values without adding more cementitious material and water and without segregation. Low slump is necessary in certain applications, such as slip-form paving, where concrete retains a certain shape without the need for formwork. On the other hand, a high-slump concrete may be necessary where complicated forms or closely spaced reinforcement is used. Under such conditions, it may be necessary to require self-consolidating concrete. References: SP-1(02); ACI 238.1R-08; ACI PRC-211.1-22; ACI 301-20; ASTM C143 Topics in Concrete: Concrete Fundamentals; Mixture Proportioning; Placing; Self-Consolidating Concrete; Testing of Concrete
Q. How is workability measured and specified?
A. The customary measure of workability is slump. ASTM C143 covers the determination of slump. The lowest acceptable slump is normally selected in preference to high slump due to a low w/cm and low amount of cementitious material, which are desirable; it also means less likelihood of segregation. The use of water-reducing admixtures, however, enables the preparation of concretes with a low w/cm and high slump values without adding more cementitious material and water and without segregation. Low slump is necessary in certain applications, such as slip-form paving, where concrete retains a certain shape without the need for formwork. On the other hand, a high-slump concrete may be necessary where complicated forms or closely spaced reinforcement is used. Under such conditions, it may be necessary to require self-consolidating concrete.
References: SP-1(02); ACI 238.1R-08; ACI PRC-211.1-22; ACI 301-20; ASTM C143
Topics in Concrete: Concrete Fundamentals; Mixture Proportioning; Placing; Self-Consolidating Concrete; Testing of Concrete
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