What is asphalt?

Asphalt pavement is made up of stone (aggregate), sand, additives and liquid (petroleum) asphalt. Liquid asphalt – a sticky black substance – is used as the binding material in asphalt pavements. It is viscous in nature and can also be found in semi solid forms. Another common term for asphalt is bitumen. The pavement – once mixed – consists of 90 to 95% aggregate and sand, and 5 to 10% asphalt or bitumen. Asphalt pavements high viscosity binds the materials that make up asphalt, while allowing it to simultaneously retain flexibility. The cooler the asphalt surface the less flexible the overall pavement. This flexibility found in asphalt pavement is one of its greatest strengths, allowing the surface to adapt to changing conditions produced by weather and the constantly changing surface beneath it. Another chief characteristic of asphalt is its ability to repel water.