Components Of Road Pavement Structure


Pavement or road surface is a durable surface material laid down on an area intended to sustain vehicle traffics. A pavement consists of different components and layers Its main function is to distribute the applied vehicular loads to the underneath layers.

Road pavement construction involves different steps such as groundwork, laying materials, etc. Groundwork is done to prepare sub-surfaces for the start of road construction. It is an essential job to be done properly to make the road surface durable and to increase the service period. So we should always choose a good groundwork specialist for this job.

Components Of Road Pavement Structure:

Following are the different components of road structure:

1. Subgrade

2. Sub-base

3. Base course

4. Surface course or wearing course

All these components belong to a typical flexible pavement, whereas rigid pavement usually consists of subgrade, subbase, and a concrete slab.

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.

This course is considered as the most important and major component of road structure because this course is to bear the impact of traffic transferred through the wearing course. It consists of a stable material like boulders, gravel, one or two layers of well-burnt bricks, etc. In case of rocky subgrade, this course is not provided.

4. Surface Course Or Wearing Course:

The topmost layer of the road pavement directly exposed to traffic is called wearing course or surfacing.

It may consist of one or more layers in case of flexible pavements. A good wearing course should be impervious and weather resisting. it should be able to resist the abrasive action of the traffic.

Also Read – Difference Between Flexible Pavements & Rigid Pavements.

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