Asphalt road surfacing is the most important part of a road; it provides protection to vehicles, road users and the long time sustainability.
Asphalt is found as one of the products of crude petroleum or as a natural deposit found all over the world. In the Australia the world asphalt is used for the makeup of the asphalt and the aggregate that it is mixed with.
Asphalt comes in many different qualities and can be applied in many different ways. Due to the versatility of asphalt, there also become many problems that can be associated. Many problems associated with asphalt surfacing are not due to the properties and quality but the design or the way it is constructed.
There are five different ways BP Bitumen describe that asphalt surfaces can fail and many with different causes and ways in which this can happen and many different ways in which they can be rectified.
1. Deformation
Deformation results in the vertical or horizontal movement of the asphalt layer from inadequate strength, pavement thickness, compaction of the surface or base and many other defects mainly from the incorrect design of the asphalt layer.
2. Cracking
Cracking can form in many different ways, each with its own causes. Many causes of asphalt cracking is due to under layers, stressing the asphalt to cracking point. This can include, swelling of the base layers, cracking of the underlying concrete layer or the introduction of tree roots.
3. Surface texture deficiencies
Surface texture deficiencies are a great problem for grip and skip resistance of an asphalt layer. This is most commonly caused from incorrect design of the asphalt surface, and includes surface flushing, ravelling, stripping, delamination, polishing or a combination of these problems.
4. Edge defects
Edge defects occur in many regional roads where roads are thin and do not have side protection for cost savings. These defects are usually caused by traffic wearing the edges and removing the outside layer.
5. Potholes
Potholes are caused due to the top layer peeling off locally or moisture penetration causing weekness. Potholes usually occur on rural roads where road surfaces are reduced for cost savings, and usually treated by filling in with additional asphalt.
Remedies for correcting problems with road surfaces can be extremely expensive, depending on the problem.
For problems where the asphalt layer has been permanently altered and on a large scale, the usual remedy is to replace the whole layer with a new design in place. Yet for localised problems, the most common remedy is to locally replace the outside layer for a short term fix.
Many remedies for road surfaces consider many different aspects, including the cost and long term use of the road. Investigations of asphalt failure are extensive throughout the world; these investigations are very important in finding the correct remedy for the problem. In many cases problems with the asphalt is the design, and therefore the initial designs of road surfaces need to be concise due to the long time affect on the roads.
When designing pavements, long term loadings need to be taken into account. For instance a rural road may only currently take a small loading, yet what will the load be in a years time or five years time.
