What is a/an....‎ > ‎

... AB?

AB, ABC, Aggregate Base or Aggregate Base Course refers to the sub-layer material under concrete or asphalt paving that is placed directly on top of the undisturbed soil so as to provide a foundation to support the top layer of concrete or asphalt. Generally consisting of a specific type of construction aggregate, it is placed by means of spreading and compacting to a minimum depth and compaction specified by the Construction Documents, thus providing the stable foundation needed to support either additional layers of aggregate or the placement of concrete or asphalt.

Aggregate Base (AB) is typically made of a recipe of mixing different sizes of crushed rock together forming the aggregate which has certain desirable properties.   An aggregate is normally made from newly quarried rock, or it is sometimes allowed to be made from recycled asphalt concrete and/or portland cement concrete.