The construction material asphalt bears the substantial amount of the paving materials. So, for example in the Federal Republic of Germany 95% of all paved roads are equipped with an asphalt surface. The need for mobility is steadily increasing.
The flexible and economical building material asphalt playing an increasing role in the aerodrome, landfill and water, as well as in the design of public squares and paths next to the classic road.
In the production of asphalt, the minerals are first dried and mixed in special mixers metered addition of bitumen into a homogeneous mass. The bitumen used in this case encloses and connects the minerals.
The changing composition of the asphalt adheres strictly to the requirements of technical regulations and is based on the proficiency tests started by production companies.
For technical and economic reasons, asphalt pavements are usually divided into various layers:
| 1.) Asphalt surface (approx. 4cm) |
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As top layer of the road, the asphalt surface is exposed to the traffic and weather directly. Due to the high mechanical and climatic stresses they must be replaced as a rule after 12 to 15 years. Particularly handy and wear resistant aggregates help to optimize their durability. |
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| 2.) Asphalt binder layer (approx. 8cm) | |
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The core function of binder is to quickly and effectively derive shear forces and vibrations from the road surface in the lower layers. Thus, it protects the outer layer particularly in high traffic and heavy braking from overloading and distortion. |
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| 3.) Asphalt base layer (approx. 22cm) | |
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The asphalt base layer serves to accommodate the high loads and to distribute them to the underlay. It is a uniform and stable surface for subsequent layers.The lowermost layer of asphalt comes to the really important role. With its coarse-grained rock mix it ensures the uniform distribution of the burden, thus increasing the load capacity of the road. If the road well maintained, a support layer can hold up to 50 years. |
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| 4.) Asphalt frost protection layer (approx. 34cm) | |
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To prevent damage caused by frost, a frost protection layer is often used below the asphalt layers. The unbound gravel, sand or chippings are extremely resistant to heat, water penetration derive quickly and prevent awakenings due to frost in the upper layers of asphalt. |
Depending on the thickness and position the different layers provide their contribution to the sustainability of road. For slightly polluted streets, paths and areas to apply the single-layer structure, which consists only of a base surface layer.
In addition to standard of mix that meet the technical regulations of the asphalt road construction, there are also special asphalts as porous/whisper asphalt, semi-rigid layers etc.
