Bitumen is a black, paste-like substance that is used in moisture insulation and asphalt construction, and it is used as the main building material in moisture insulation and asphalt. There are different types of bitumen, each of which has a different application. This substance is produced in an oil refinery.

Bitumen is a hydrocarbon substance that has a definition, sources, and special characteristics. Bitumen materials are more diverse than oil because bitumen has other resources besides oil. Bitumens are divided into the following three categories depending on their origin

A- Natural bitumen

2- Petroleum bitumen

3- Tar


1- Natural bitumen

A black substance that comes out of the earth and is usually in the form of large pieces of stone, is called GilSonite, which is also called natural bitumen. The production of this product has been done inside the ground, which makes this mineral more valuable in the Iranian and international markets. Iran is one of the countries that has large gilsonite production mines and has been able to supply most of the gilsonite produced in the world market. Natural bitumen in natural conditions and in the open environment is caused by the evaporation and conversion of crude oil in nature and due to the passage of time (Millions of years) it is gradually produced and obtained. This type of bitumen is called natural or mineral bitumen, which has special uses.

And this natural bitumen in our country is usually known as Gilsonite, and in fact it is crude oil hardened by pressure to determine the characteristics of natural bitumen, its color, smell, softening point, humidity, amount of ash, amount of carbon, and solubility of that item. Attention and measurement are placed.


2- Petroleum bitumen

At the beginning of the 20th century, petroleum bitumen obtained from refining crude oil came to the market and replaced mineral and natural bitumen in asphalt pavements and other industrial uses. This type of bitumen is obtained from the refining of crude oil in distillation towers and finally remains at the bottom of the tower at a temperature of more than 380 degrees. Usually, this type of bitumen is obtained from the distillation of crude oil. Such bitumen is called petroleum bitumen or distillate bitumen. Oil bitumen is the product of two stages of crude oil distillation in the distillation tower. In the first stage of distillation, light substances such as gasoline and propane are separated from crude oil. This process is carried out in a pressure close to one atmosphere (unit). Heavy compounds such as diesel and kerosene are removed in the second stage. This process takes place in a pressure close to a vacuum.


3- Tar

Types of bitumen Chemically, there are different classifications for bitumen, two of the most common of which are the classification based on whether the bitumen is natural or petroleum, and the more common one is based on the type of bitumen source, i.e., oil, coal, or wood.

(Tar) Bitumen This type of bitumen is sometimes known by the same name due to its similarity in appearance and similar use to petroleum bitumen. Because the source of this type of bitumen is different from petroleum bitumen, it has different chemical composition and physical properties, as a result, it is a general word for liquids that Tar. It has a different behavior during use and performance in service than burning natural organic materials such as wood or coal and their destructive distillation in the absence of air. Two types of tar can be prepared by burning or carbonizing coal according to the type of process.