The wearing course, also known as a friction course or surface course, is the upper layer in roadway, airfield, and dockyard construction.
The term 'surface course' is sometimes used slightly different, to describe very thin surface layers such as chip seal.
In rigid pavements the upper layer is a portland cement concrete slab.
In flexible pavements, the upper layer consists of asphalt concrete, that is a construction aggregate with a bituminous binder.
Stone mastic asphalt is a type of flexible pavement wearing course which is typically used for heavily trafficked roads.