Bitumen may refer to either a naturally occurring mixture of various organic liquids, also called crude bitumen, or a residue yielded in the distillation process of coal or petroleum, called refined bitumen. It is a brown-black, extremely viscous, tar-like material that was the first oil product utilized by humans because of its adhesive and cohesive properties. Its principle contemporary usage is in the paving of roads. In North America, it is referred to as asphalt.
Crude bitumen can be found as a solid or semi-solid material, and consists mostly of hydrocarbons. Its formation can be traced to the decomposition of organisms deep within the Earth’s crust, where they were affected by intense pressure and heat. This process produced materials such as bitumen. Natural deposits can be found all over the world, with the largest located in Canada and Venezuela.
Historical usages of bitumen can be traced back 8,000 years with its presence in various Neanderthal tools. Human usages of this material are dated as far back as 5000 BC. Its ancient origin can also be seen in what is believed to be the source of the name, from the ancient Sanskrit term "jatu" and "jatu-krit," meaning "pitch" and "pitch creating" respectively, a reference to tree resin pitch.
Bitumen use varies according to geographical and societal contexts; however, it was historically employed for tasks such as water-proofing, building construction, and the composition of more complex tools that required some binding element. It was also believed that it was used in the mummification process in Ancient Egypt, serving as a type of preservative. While this claim has been disputed, the term mummy is derived from the Arabic term for bitumen, "mumiye."
Natural deposits of of this substance are too low for present human consumption and demand. Thus, the majority is produced through a fractional distillation processes. Refined bitumen is made from crude petroleum oils, and has been produced in this manner since the late 19th century. The heating of crude oil produces a residue, which is then used to manufacture various grades of bitumen. More recent advancements have led to its production from non-petroleum sources such as corn, rice, and molasses starches.
The construction industry uses 85% of bitumen for the binding of asphalt within roads, while 10% is applied for roofing. It has proved a valuable material because of its resistance to the elements.
