National Research Council (U.S.). Highway Research Board. Committee on Chemical Additions and Admixtures for Concrete
Published: 1971
Total Pages: 60
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An admixture is any material other than water, aggregates, and hydraulic cement that is used as an ingredient of a concrete or mortar mixture and added to the batch immediately before or during mixing. 4 types of admixtures are discussed: (1) accelerators, the most common of which is calcium chloride; (2) air-entraining, to protect the concrete against the damage it may suffer if the paste becomes saturated with water and then freezes; (3) retarders and water reducers, which extend setting time 30 to 50 percent to compensate for placement temperatures, to avoid cold joints, or to avoid undesirable effects of displacements and deflections; and (4) pozzolans, which react with hydroxides to form compounds with cementitious properties, and usually produce a lower cost concrete.
