What Are The Components Of Road Pavement Structure ?
1. Subgrade
The finished and compacted surface of earthwork on which a road pavement rests is called subgrade or formation.
The subgrade of a road may be provided on an embankment, in cutting or existing ground level depending upon the topography and the finalized formation level. It consists of well compacted natural soil brought to the required camber and gradient.
The thickness and type of pavement structure depend upon the supporting power of the subgrade because the entire load of the pavement, including the load of traffic transmitted through the pavement, is ultimately taken up by the subgrade.
2. Sub-base
A layer of granular material provided in between the subgrade and the base course in a road pavement is known as a sub-base.
It is provided as an additional layer when the subgrade is of poor quality. It consists of a layer of comparatively cheaper material like burnt clinker, natural gravel, or slag.
3. Base Course
A layer of boulders or bricks provided over the subbase or immediately over the subgrade in the absence of sub-base in a road pavement is called base course or soling or foundation course.
