Where Does Bitumen Come From 6g122p

Where does bitumen come from? Bitumen can be found in the natural state, but the bitumen used nowadays for the surfacing of roads and a variety of industrial uses is produced in refineries from special qualities of crude oil. Natural bitumen In its natural state, bitumen is found oozing out onto the surface of the earth (USA, Israel, Mexico, Venezuela). Not far from Los Angeles (USA), accumulations of natural bitumen have been found, resulting from oozing of oil from the remains of numerous herbivorous animals, of something like a thousand smilodons (a genus of sabre-toothed tigers with prominent canine teeth alive in the Pleistocene period) and of more than one thousand five hundred wolves. The carnivorous animals, attracted by the presence of their prey bogged down in this natural trap, became prisoners of the sticky viscous bitumen in their turn. Dating the remains has shown that some of these animals lived fifteen thousand years ago. Archaeologists have found traces of the use of natural bituminous materials dating from 5 000 BC. Bitumen as caulking for Noah’s Ark and Moses’ cradle is mentioned in the Old Testament. More recently, particularly in the XIXth century, painters used asphalt or bitumen on their canvasses to obtain blacks with a brown tint. For example, in his celebrated painting, The Raft of the Medusa, Géricault made use of bitumen of Judea to obtain the brownish tones and a violent chiaroscuro. A special distillation Nowadays, natural deposits are no longer sufficient for our requirements. The greater part of the bitumen used to meet the demands of civil engineering and construction is extracted from crude oil. Scientists agree today on the animal origin of crude oil. Over geological ages, the transformation of marine micro-organisms (plankton), deposited in the sedimentary layers of rocks, led to the formation and accumulation of numerous varieties of crude. Bitumen is obtained essentially by distillation of a blend of crudes containing at least one bitumen crude. The others, which are lighter, go to satisfy requirements for different types of fuel and combustibles. Contrary to a common but mistaken idea, bitumen is not an oil residue that the petroleum industry wants to get rid of at little cost. In reality, to produce bitumen of good quality with constant properties, refiners meticulously select one or more bitumen crudes, following very strict internal approval procedures. Of the 1 300 types of crude oil classified worldwide, only 10 % are suitable for producing bitumen capable of meeting the specifications for use. These types are known as bitumen crudes (in practice, about 30 are usable in Europe). In a nutshell, bitumen is a blend of hydrocarbons, solid and semi-solid and brown or black in colour. The properties of bitumen products Each type of bitumen has its own characteristics: there are those capable of evacuating water and of deadening noise, those with high cohesion resistance to powerful mechanical forces (such as the age of heavy-goods vehicles) and also synthesized bitumen products. Bitumen types can be defined by two properties: - penetrability: a measure of hardness; - softening temperature: the maximum temperature for the use of bitumen as a road surfacing.

Industrial applications of bitumen 90 % of all bitumen is used in road construction and 10 % for industrial purposes. Thus industrial applications constitute the second domain of application for bitumen. Its watertight and airtight properties, its binding power and its flexibility make it an excellent proofing material. Its insulating properties and its vibration-absorption capacity mean that it can contribute to the thermal and acoustic insulation of buildings. Bitumen enters into the composition of paints and varnishes to ensure protection against humidity and corrosion.

Bitumen can play a part in many other applications: - Sound insulation of automobile and electrical appliance components (reduction of noise caused by vibration and resonance, by capitalizing on the sound-deadening capacity of bitumen) ; - ting mastic for works of art ; - coatings for wrapping papers ; - insulation in electric batteries ; - protective sheathing for pipes and electric cables ; - condensers ; - carpet linings ; - pulverized bituminous ‘mulch’ for treating cultivation areas or fixing bare surfaces and paintwork ; - material for containment of many types waste, including nuclear waste.