Types of road treatment
The treatment we use will depend on how damaged the road is. It may be sealed to restore grip, or the existing surface could be replaced with a new one.
Surface dressing involves sweeping the road clear of debris before a hot bitumen binder is sprayed over the existing surface. This softens the surface and seals cracks and joints. While the surface is still soft, a layer of new stone chippings is spread over it and rolled to help them bed in to the existing road. This is continued as traffic drives over the road. The treatment leaves loose chippings on the surface of the road for several weeks after the dressing until the bedding in process is complete.
Micro asphalt works, also known as microsurfacing, involve sweeping the road clear of debris then laying a thin layer of asphalt over the existing surface, usually in two coats, to fill defects and even out dips in the road surface. Unlike conventional asphalt, the material is laid cold and sets after about 30 minutes. Although the road can be opened to traffic after about 30 minutes, the material stays relatively soft for several weeks after laying, so not all roads are suitable for this treatment.
Resurfacing involves replacing the surface of a road. In some, mainly rural areas, it is possible to ‘overlay’ a new surface straight over the top of an existing one. But on roads with kerbs, pavements or manholes covers, a layer of the old surface is usually scraped away – known as planing – and a new surface is ‘inlayed’ at the same level. Sometimes only 30-40mm of the surface layer is removed but if the damage to the surface is deeper, more of the existing road will be removed before the planed surface is cleaned and sprayed with bitumen to help the new surface stick to it. The new asphalt is laid at a high temperature before being rolled to compact it and give an even surface.
Retreading involves breaking up the existing road surface which is then mixed with bitumen and rolled to create a solid structural layer, then sealed. In most cases, a surface layer of asphalt or microasphalt is also applied, which can happen several weeks after the road has been retread.
Velocity patching involves blasting all debris from the defect with high velocity air, before a cold bitumen emulsion is applied to seal any cracks. An aggregate mix is then evenly applied to help level out the defect as it bonds to the existing surface of the road. This repair is fast and efficient, repairing defects in around two minutes.