Asphalt

Asphalt, basically a by product of the distillation of types of petroleum, is a sticky semi solid substance with a dark color. The molecular structure of asphalt is complex and in general it can be said to be composed of a different saturated and unsaturated hydrocarbons with their molecules containing more than 150 atoms. On mentioning the word asphalt, the general idea that comes to mind is “the stuff used to construct road”. Indeed asphalt does find enormous usage as a cementing material for construction of roads and pavements – in fact, among other uses such as waterproofing, this is its primary use.

Composition and Properties

Asphalt is composed of molecules of hydrocarbon, both saturated and unsaturated having more than 150 atoms in its molecules. Although the materials which constitute it are not well characterized, it basically contains oxygen, sulfur, nitrogen, hydrogen and nickel, among other trace elements like vanadium and nickel. It is regarded as a thermoplastic. A thermoplastic is defined as a polymer which becomes soft on application of heat and hardens on being cooled.


Due to its nature of cementing the particles together, asphalt is used to make roads. This is owing to the fact that a large number of the compounds that make up asphalt are polar in nature. These compounds contain functional groups such as alcohol, thiol and carboxyl groups among others. This resulting polarity is thought of to be the reason due to which it clusters into molecules of high molecular weights almost giving it a polymer like effect. This sticky nature results it in forming composite material with the aggregate matter used in making roads. This is actually known as asphalt concrete which is used in road making. Although the thermoplastic nature does in fact act more as a problem when it is used in roads, there are various ways of removing the complications caused by its nature and maximizing its utility.

 

Production

Asphalt is produced as residual matter left after the fractional distillation of petroleum or from coal as a result of destructive distillation. Further processing of the black sticky residue left behind is done keeping in mind the uses it should serve:

 

Uses

Asphalt has numerous uses with one of the primary being its use in making roads, that is, asphaltic concrete. There are numerous forms and methods of applying it on roads and pavements. Owing to its waterproofing and binding properties, is also used as a roofing material or even in underground tanks.