Flexible pavement is a type of road surface composed of multiple layers designed to flex or bend under traffic loads. It typically includes a surface course made of bituminous material such as asphalt, along with underlying base and subbase layers of aggregates. The bituminous surface, often hot mix asphalt, has a plastic nature that allows it to deform elastically under loads and distribute stresses through the layers down to the subgrade soil. The pavement's flexibility helps it absorb traffic impacts and reduces damage by allowing some deflection. The structure generally consists of:
- A surface course (asphalt or bituminous concrete) providing a smooth, waterproof, and skid-resistant riding surface.
- A base course made of crushed rock or gravel to provide strength and distribute loads.
- A subbase course beneath the base for additional load distribution and frost protection.
- The subgrade soil beneath all the pavement layers.
Flexible pavements are named so because they reflect the combined deflection of all these layers due to traffic loads. This type of pavement is common worldwide due to its relatively low initial cost, ease of repair, and quick opening to traffic after construction. However, flexible pavements require regular maintenance since they are prone to deterioration like cracks and potholes with heavy use and poor drainage. Overall, flexible pavements work as a layered system where each layer contributes to load distribution and structural support, allowing the pavement to flex without breaking abruptly.
