DEFINITION of 'Bitumen'
A substance produced through the distillation of crude oil and known for its waterproofing and adhesive properties. Bitumen production through distillation removes lighter crude oil components, such as gasoline and diesel, leaving the “heavier” bitumen behind. It is often refined several times in order to improve its grade.
BREAKING DOWN 'Bitumen'
In modern times bitumen is most likely to be manufactured from crude oil, but bitumen can be found in nature. Deposits of naturally occurring bitumen can be found at the bottom of ancient lakes, where prehistoric organisms have since decayed and have been subjected to heat and pressure.
Bitumen is generally for industry use. Early uses of bitumen involved its natural adhesive and waterproofing characteristics, but it was also used as a medicine. It was used to bind building materials together, as well as to line the bottoms of ships. Herodotus, a fifth century BC Greek historian, claimed that the walls of ancient Babylon were strengthened through the use of bitumen. The material was traded between ancient civilizations.
Bitumen is composed of complex hydrocarbons, and contains elements such as calcium, iron, sulfur, and oxygen. The quality of material and ease of production is dependent on the source and type of crude oil it is derived from.
The material is used most often in road paving, in which bitumen is called asphalt. Most roads in the United States is made of either bitumen, or a combination of bitumen and aggregates, such as concrete. Bitumen can be recycled, meaning that engineers replacing asphalt roads can reuse the material on other road projects. It is also used in the creation of roofing products due to its waterproofing qualities
Under heavy loads bitumen can be permanently deformed, depending on the composition of the asphalt mixture, the ambient temperature, and the amount of stress places on the material. Bitumen oxidizes, which can leave the asphalt brittle and result in it cracking.