A layer used in a pavement system between the subgrade and the base coarse material.
the lowest molding of an architectural base or of a baseboard
a portion of a base, usually consisting of a single axial polygon.
The material laid on the subgrade below the base either for the purpose of making up additional pavement thickness required over the subgrade, or to prevent intrusion of the subgrade into the base, or to provide a working surface on which the remainder of the pavement can be constructed.
The material placed immediately over the subgrade.
The compacted soil which forms the base for the base of a paved road.
In highway engineering, subbase is the layer of aggregate material laid on the subgrade, on which the base course layer is located. It may be omitted when there will be only foot traffic on the pavement, but it is necessary for surfaces used by vehicles.