Pavement Structural Layers

To ensure all-year-round operation of vehicles traffic on a road, the carriageway is covered with a pavement. The pavement is laid on the surface of the roadbed. It can have rigid or semi-rigid structure. The pavement resists traffic stresses and climatic factors.

The stresses induced in the pavement by motor vehicle wheels attenuate with the depth. This enables the pavement to be designed in the form of a multilayer structure. The pavement consists of the following layers: the surfacing, the pavement base, the sub-base and the subgrade.

2. Below the surfacing base coat is the pavement base, a strong bearing layer of stony material or stone with a binding matrix. This layer is designed to distribute the individual wheel-loads. The pavement base is not subjected to the direct action of automobile wheels.

3. The sub-base is a layer of earth or stone materials, resistant to moisture, inserted when necessary between the pavement base and the roadbed. The sub-base is made of gravel, slag, soil treated with binding agents, sand, etc. Subbase is often the main load-bearing layer of the pavement. The primary functions of the sub-base are to provide structural support and improve drainage. The quality of subbase is very important for the useful life of the road.

4. The subgrade is the native material underneath a pavement. It comprises the thoroughly compacted upper layers of the roadbed upon which the layers of the pavement are laid. It is also called formation level.

Source: Английский язык. Контрольные задания. / Л.В. Лукина, Л.Н. Крячко, О.Ф. Нестерова,Н.В.Сидорова. Воронеж: Воронеж. гос. арх.-строит. ун.-т., 2009 – C.72-73