Research Engineer, United States Bureau of Reclamation, Denver, Colo.
Pages: 13 Published: Jan 1956
Frequently powdered mineral admixtures can be used in concrete with advantage. They may improve the physical texture of the fresh concrete, imparting to it extra workability; alleviate bleeding; and, when possessing pozzolanic properties or hydraulic properties, add to its final strength. However, the advent of air-entrainment, with its marked effect on the workability of concrete, has in great measure displaced mineral admixtures as a means for improving concrete mixes. The contribution of admixtures to concrete quality is more noticeable in lean mixes than in rich ones and is most marked in mixes which are deficient in fines. Those admixtures possessing pozzolanic properties offer the greatest advantage to mass concrete, lowering the heat of hydration and permitting the use of otherwise difficult but desirable lean mixes. Many mineral admixtures have also been shown to inhibit the alkali-aggregate reaction.
Paper ID: STP39450S