This specification covers the materials and the test methods for use in chemical admixtures to be added to hydraulic-cement concrete mixtures in the field. The seven types of admixtures are indicated as follows: Type A—water reducing; Type B—retarding; Type C—accelerating; Type D—water reducing and retarding; Type E—water reducing and accelerating; Type F—water reducing, high range; and Type G—water reducing, high range, and retarding. The materials used in the concrete mixtures shall include Type I or Type II cement, pozzolan, fine and coarse aggregates, and air-entraining admixture. Samples of freshly mixed concrete from at least three separate batches for each condition of concrete shall be tested in accordance with the slump, air content, time of setting, and water content tests. Physical properties retesting shall consist of uniformity and equivalence tests using infrared analysis, which is intended to compare qualitatively the composition of different samples; residue by oven drying, which shall be either a forced circulation type or one with provision for free access of air; and specific gravity determination using hydrometers. Test specimens of the hardened concrete shall be prepared in accordance to compressive strength, flexural strength, resistance to freezing and thawing, and length change.
KeywordsASTM C494 - Chemical Admixtures for Concrete
ICS CODE91.100.30 (Concrete and concrete products)
ASTM C494 / C494M-17, Standard Specification for Chemical Admixtures for Concrete, ASTM International, West Conshohocken, PA, 2017, www.astm.org