Bitumen
From Wikipedia, the free encyclopedia
Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, entirely soluble in carbon disulfide, and composed primarily of highly condensed polycyclic aromatic hydrocarbons.
Bitumen is the residual (bottom) fraction obtained by fractional distillation of crude oil. It is the heaviest fraction and the one with the highest boiling point.
In British English, the word 'asphalt' refers to a mixture of mineral aggregate and bitumen (or tarmac in common parlance). The word 'tar' refers to the black viscous material obtained from the destructive distillation of coal and is chemically distinct from bitumen. In American English, bitumen is referred to as 'asphalt' or 'asphalt cement' in engineering jargon. In Australian English, bitumen is sometimes used as the generic term for road surfaces.
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[edit] Uses
Bitumen is primarily used for paving roads. Its other uses are for general waterproofing products, including the use of bitumen in the production of roofing felt and for sealing flat roofs. It is also the prime feed stock for petroleum production from tar sands currently under development in Alberta, Canada.
In the past, bitumen was used to waterproof boats, and even as a coating for buildings; it is possible, for example, that the city of Carthage was easily burnt down due to extensive use of bitumen in construction.
Vessels for the heating of bitumen or bituminous compounds are usually excluded from public liability insurance policies.
Most geologists believe that naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae and other once-living things. These organisms died and their remains were deposited in the mud on the bottom of the ocean or lake where they lived. Under the heat and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.
[edit] Applications in climate change
The world has become increasingly concerned over the global climate change caused by pollution that is released into the atmosphere. Most of the emissions are derived from burning fossil fuels. This has led to the introduction of bitumen alternatives that are more environmentally friendly and non toxic. Bitumen can now be made from non-petroleum based renewable resources such as sugar, molasses and rice, corn and potato starches. Bitumen can also be made from waste material by fractional distillation of used motor oils, which is sometimes disposed by burning or dumping into land fills.
Non-petroleum based bitumen binders can be made light-colored, which helps reduce the temperatures of road surfaces which contribute to the urban heat island effect. [1]
