When a road surface reaches the end of its useful life it must be replaced. This is generally caused by the number of vehicles that have passed over the road, changes in the drainage of the road or structural failure of the sub-base layers/construction. These conditions are not caused by any chemical changes in the surface material itself.
The surface that needs replacing can be removed in several ways, including the use of pneumatic and hydraulic breakers and road planers. When such a milling operation is undertaken on an asphalt road using a road planer it will produce a variation of material that can be used in a number of different civil engineering applications, this can include: capping, sub base, driveways, hard-standings, car parks and the manufacture of new road surfacing materials.