The strata of material between the underlying native sub-grade and upper base course. Sub-base material is larger than base course.
Commonly made from stone pieces, larger than that in the base materials. It is a layer of particular thickness, placed on a subgrade, giving support to the base material.
The layer of material placed to furnish strength to the base of a road.
Imported material that is intended to form the foundation for final surface preparation.
The layer or layers of specified or selected material of designed thickness placed on a subgrade to support a base course. Aggregate sub-bases are typically made of stone pieces larger than that in bases.
A layer of material on the sub-grade that provides a foundation for a pavement surface.