Technical Works & Road Construction
Sector
Construction
Location
Greece
Years of Experience
1986 - today
Remote Support
Consulting Available
The vast majority of refined asphalt is used in construction: primarily as a constituent of products used in paving and roofing applications. According to the requirements of the end use, asphalt is produced to specification. This is achieved either by refining or blending. It is estimated that the current world use of asphalt is approximately 102 million tonnes per year.
Approximately 85% of all the asphalt produced is used as the binder in asphalt concrete for roads. It is also used in other paved areas such as airport runways, car parks and footways. Typically, the production of asphalt concrete involves mixing fine and coarse aggregates such as sand, gravel and crushed rock with asphalt, which acts as the binding agent. Other materials, such as recycled polymers (e.g., rubber tyres), may be added to the asphalt to modify its properties according to the application for which the asphalt is ultimately intended.
Earthwork is one of the major works involved in road construction. It involves the removal of topsoil, along with any vegetation, before scraping and grading the area to the finished ‘formation level’. This is usually done using a tractor shovel, grader or bulldozer. Below the formation level, the soil is known as the ‘subgrade’. It is essential that the strength of the subgrade is tested prior to earthwork beginning. Most earthworks are formed by cut-and-fill, and the type of ‘fill’ material must be considered, not only in terms of its physical properties, but on the conditions in which it is to be used, and the methods of compaction.
Depending on its quality, compressible subsoil may be removed or stabilised. If the cost of full or partial excavation of subsoil is uneconomical and would be likely to result in consolidation, sand wicks or sand drains may be used. Sand wicks are sand-filled boreholes beneath the road embankment that give greater stability to the soil by decreasing the length that water has to travel in a drainage path, so dissipating water pressure. Sand drains alongside the road are used to intercept ground water. Subsoil drainage should be provided to deal with seepage through pavements and verges, from higher ground and a result of the seasonal rise and fall of the water table.