Construction of paved roads can benefit from the application of geosystems. They are claimed to improve durability and resistance to thermal stress, cycling fatigue and cracking of the bituminous bound layers and to increase load bearing capacity of the sub-base/foundation layer. These in turn result in significant reduction of thickness of the layers and might increase significantly the life of the pavement.
It is argued that geosynthetic reinforcement of the asphalt laid on top of a concrete pavement delays the appearance of reflection cracking. However, trialling and long term monitoring of road and airfield sites where this technique has been applied is still underway in the UK. The interim results of this research are that the beneficial effect of the geogrids/geotextiles varies depending on the specific product and that geosynthetics are potentially more difficult to install and more costly than other techniques. Use of geosynthetics in asphalt overlay still requires special approval by the Highways Agency and the Defence Estates
Unpaved roads, used as haulage or temporary roads, can be effectively reinforced by geogrids/steel mesh inserted within the base layers. This enables a reduction in the thickness of the granular material used. Durability and resistance to chemical attacks are important considerations in the choice of geogrids if the unpaved roads are to be incorporated into permanent works. Further information on this application is given in the application specifically on “working platforms”.
Geotextiles and geogrids can be used in the maintenance of byways which might be used by motor vehicles. Geotextiles provide a separation layer between the subgrade and the granular material used to build the byway thus avoiding degradation of the granular layers. Geogrids are used to reinforce the granular layer, thus allowing for the use of lower quality materials or lower thicknesses.
Geosynthetics can be used to reinforce both paved and unpaved roads and increase their load carrying capacity and durability, thus realising both immediate and long term savings. These are some examples of the benefits that can be realised:
The savings highlighted above are matched by environmental benefits. Geosystems achieve resource efficiency through reduction of the need for virgin/imported materials.
This results in savings of natural resources. Furthermore, the considerable reduction in transport requirements (less haulage of new materials and disposal of waste) results in significant avoidance of greenhouse gas emissions.
In many cases the requirement for maintenance interventions is reduced with environmental benefits in terms of reduced construction noise and less traffic disruption in the neighbouring area.