Air entrained concrete is produced using specialist admixtures added to the concrete during production to entrain micro bubbles of air into the mix. Although specifically designed, the controlled addition of air into the concrete mix has the effect of reducing the compressive strength which must be accounted for in the concrete mix design process.
Air entrainment is utilised principally to increase the resistance to freeze thaw damage of a given concrete mix. The entrained micro bubbles increase the durability of the concrete in applications where it may become saturated and exposed to freeze thaw cycles. A secondary benefit of air entrainment is to improve the cohesion and workability of a mix and this property is most applicable to slip-formed concrete applications such as extruded central barriers and kerb mixes and climbing slip-formed structures.
It is important to note that air entrained concrete is not suited to flatwork applications where a power trowelled finish or surface hardening products are to be applied, e.g. internal floor slabs. Over working or over compacting of the concrete either on the surface or throughout the placed element can remove some or all of the entrained air.
Increased durability in applications where saturation of the concrete and freeze thaw may be a concern.