Asphalt is a bituminous product that is produced from crude oil by a distillation process. It is mixed with aggregate to produce a waterproof, smooth wearing surface that is resilient and will resist pressures exerted by wheeled loads. The asphalt binds the aggregate particles together in a matrix and waterproofs the mixture. The aggregate provides the load-bearing capacity of the mixture and resists abrasion to the surface. Because of their plastic nature, asphalt pavements often are referred to as flexible pavements.