Air-entraining agents are liquid chemicals added during mixing to produce microscopic air bubbles in concrete. These bubbles:

•  Improve durability by increasing resistance to freeze- thaw cycles.

•  Improve workability.

•  Reduce bleeding and segregation of concrete mixtures.

Air entrainment is usually specified for outside concrete slabs and is specified at 5-8% of the mix. Air entrainment is not necessary for interior concrete. Air Entrainment is covered in ASTM C260 & ACI 116R-90.