Road Planings is a recycled material. It's formed when a machine known as a "planer" mills the surface of a road into small chunks. These are usually around 40mm or smaller in size. They are also sometimes produced by crushing larger pieces of tarmac from smaller projects such as driveways. This material is not suitable for use in most projects, as road planings are made from asphalt and will naturally degrade and perish over time. This is, as opposed to other aggregates which are made from inert materials that do not change shape or form when exposed to the elements. They are however suitable for use as a temporary surface to improve ground stability for example on dirt tracks and haul roads.