The asphalt pavement structure layer can be composed of a surface course, base course, subbase course, and cushion course. The asphalt structural layer of asphalt pavement itself belongs to the category of flexible pavement, but in addition to flexible materials, the base layer can also use rigid cement concrete or semi-rigid hydraulic materials.
1. Topping
The surface layer is a structural layer that directly bears the repeated action of the wheel load and the influence of natural factors, and can be composed of 1 to 3 layers. The surface layer should be equipped with an anti-slip, wear-resistant, dense, and stable asphalt layer according to the requirements of use; the middle surface layer and the lower layer should choose appropriate asphalt structure layers according to road grade, asphalt layer thickness, and climatic conditions.
2. Grassroots
The base layer is set under the surface layer, and together with the surface layer, transmits the repeated action of the wheel load to the base layer, cushion layer, and soil foundation, and plays the main load-bearing role. The strength index of the base material should have higher requirements. The base layer can be set up with one or two layers depending on the road grade or traffic volume. When the base layer is thicker and needs to be constructed in two layers, it can be called the upper base layer and the lower base layer respectively.
3. Subbase
The sub-base layer is set under the base layer, and together with the surface layer and the base layer, it bears the repeated load of the wheel and plays a secondary load-bearing role. The strength index requirements of the subbase material can be slightly lower than that of the base material. One or two layers can be set up for the base layer depending on the road grade or traffic volume. When the sub base is thicker and needs to be constructed in two layers, it can be called the upper subbase and the lower subbase respectively.
4) Cushion
A cushion is a structural layer set between the subbase and the soil foundation, which plays the roles of drainage, water isolation, antifreeze, and antifouling.
