The asphalt pavement structure layer can be composed of surface layer, base layer, base layer and cushion layer. The asphalt structural layer of asphalt pavement itself belongs to the category of flexible pavement, but its base layer can also use rigid cement concrete or semi-rigid hydraulic materials in addition to flexible materials.
The surface layer is a structural layer that directly bears the repeated action of wheel load and the influence of natural factors, and can be composed of 1 to 3 layers. The surface layer should be set up according to the requirements of the use of anti-slip, wear-resistant, dense and stable asphalt layer; The asphalt structure layer should be selected according to highway grade, asphalt layer thickness, climate conditions and so on.
The base layer is set under the surface layer, and together with the surface layer, the repeated action of the wheel load is transmitted to the base layer, the cushion layer and the soil foundation, which plays the main bearing role. The strength index of base material should have higher requirements. The basic level can be set up one or two layers according to the needs of highway grade or traffic volume. When the base is thick and needs to be divided into two layers, it can be called the upper base and the lower base respectively. Superior Driveway Paving Companies Charleston SC Homeowners Prefer.
The base layer is set under the base layer, and together with the surface layer and the base layer, bear the wheel load repeatedly, and play a secondary bearing role. The strength index of the base material is slightly lower than that of the base material. One or two layers can be set up according to the needs of highway grade or traffic volume. When the base is thick and needs to be divided into two layers, it can be called the upper base and the lower base respectively. Cushion layer is a structural layer between the base and the soil foundation, which plays the role of drainage, water insulation, antifreeze and antifouling.
Performance of asphalt pavement
Asphalt pavement is usually used to pave the pavement surface, it is directly affected by vehicle load and atmospheric factors, while the physical and mechanical properties of asphalt mixture produced by asphalt plants are greatly affected by climate factors and time factors, so in order to make the road to provide stable and durable services for vehicles. Asphalt pavement must be required to have the following important characteristics:
- Asphalt pavement has high temperature stability
High temperature stability is the ability of asphalt pavement to resist flow deformation. Since the strength and stiffness of asphalt pavement decrease significantly with the increase of temperature, asphalt pavement should have good high temperature stability in order to better ensure that the asphalt pavement will not produce diseases such as wave, push, rutting, hugging and other diseases under the repeated action of driving load in high temperature season.
- Asphalt pavement has low temperature crack resistance.
Low temperature crack resistance refers to the ability of asphalt pavement to resist low temperature shrinkage cracks. As the temperature of asphalt pavement decreases, the stiffness increases and the variable swelling capacity decreases. Under the action of external loads, some of the stress is too late to relax, and the stress gradually accumulates. When the cumulative stress exceeds the tensile strength of the material, the cracking occurs, which will lead to the destruction of the pavement. Therefore, the asphalt pavement should have lower stiffness and greater anti-deformation ability at low temperature to meet the low temperature anti-cracking performance.
- Asphalt pavement has water stability
Water stability refers to the ability of asphalt pavement to resist the erosion of water and gradually produce asphalt film stripping, dropping grain, loose, pit and damage. This is because the existence of water on the one hand reduces the adhesive force of the asphalt itself, but also destroys the adhesive force between the asphalt and the mineral in the asphalt pavement, thus accelerating the occurrence of spalling phenomenon, resulting in water damage on the road. Therefore, the asphalt pavement must have water stability, so as to ensure the durability of the pavement.
- Asphalt pavement should have fatigue resistance
Fatigue resistance refers to the ability of asphalt pavement to resist damage under repeated loads. It is because the asphalt pavement is subjected to the repeated action of the wheel load during use, and is in the state of stress and strain overlapping for a long time, resulting in the gradual decline of the structural strength of the pavement. When the load is repeated for more than a certain number of times, the stress generated in the pavement under the load will exceed the structural resistance after the strength is reduced, causing cracks in the pavement and fatigue fracture damage. Therefore, the asphalt pavement should have fatigue resistance.