Air Entraining

BTA 5700

Air entraining is an admixture that causes the development of a system of microscopic air bubbles in cement paste during mixing, usually to increase its resistance to freezing and thawing and to improve workability

Air-entraining agents are compounds that entrain microscopic air bubbles in cement compositions, which then harden into concrete having microscopic air voids. Entrained air dramatically improves the durability of concrete exposed to moisture during freeze–thaw cycles and greatly improves the concrete’s resistance to surface scaling caused by chemical deicers. Air-entraining agents can also reduce the surface tension of a fresh cement composition at low concentration, increase the workability of fresh concrete, and reduce segregation and bleeding. Air-entraining agents are added in an amount of about 0.001–0.1 wt%, based on the weight of dry cement to yield a desired level of air in a cement composition. The particular amount used will depend on materials, mix proportion, and mixing conditions.