Bitumen

Bitumen is a petroleum-based product that is virtually non-volatile and extremely viscous or almost solid. It is mainly produced from crude oil and is characterized by excellent sealing and binding properties.

Definition of bitumen
Bitumen, also known as natural bitumen, is an almost non-volatile, sticky and sealing product which, according to DIN EN 12597, is composed of various hydrocarbons. It is mainly used in industry as a binder in asphalt and other applications.

Background / Origin
The term "bitumen" is derived from the Latin "bitumen", which means "earth pitch". From a chemical point of view, bitumen is a mixture consisting of an oily base mass, the maltenes, and higher molecular weight asphaltenes. It should not be confused with tar, which is made from coal and is no longer used as a building material.

Bitumen can occur both naturally, such as in the La Brea asphalt lake in Trinidad, and industrially from crude oil, mainly as a residue from vacuum distillation. This process produces bitumen, which is further processed by air blowing to optimize its properties. A short blowing time produces road bitumen, while a longer blowing time produces oxidation bitumen, which is mainly used as industrial bitumen.

Bitumen has no properties that are hazardous to health or water, but the vapors produced during heating may contain carcinogenic polycyclic aromatic hydrocarbons (PAHs). It is chemically stable against certain acids and bases, but reacts violently with oxygen at high temperatures and in the event of fire.

Properties
Bitumen has specific physical and chemical properties that make it suitable for various applications:

Composition:

Bitumen consists of maltenes and asphaltenes.
- Physical characteristics: At ambient temperature, bitumen is extremely viscous or almost solid.
- Quality differences: Bitumen is classified according to the needle penetration test in accordance with DIN EN 1426. Examples include grades such as 70/100, 50/70, 30/45 and 20/30, with smaller numbers indicating "harder" bitumen grades.
- Chemical characteristics: Bitumen is virtually insoluble in water and can be modified by additives to produce polymer-modified bitumen (PmB), which has improved properties such as better stability and fatigue behavior.

Application and importance in the market
The main application of bitumen is in the production of asphalt, which combines aggregates with bitumen. Other industrial applications include the production of roofing and waterproofing membranes and sealants. In 2014, 3.7 million tons of bitumen were produced in Germany, while global consumption was around 100 million tons. Around 85% of this consumption is accounted for by asphalt production for roads and runways. Bitumen consumption is highly cyclical and depends on the respective economic cycles in road and building construction.

Differentiation from similar terms
Bitumen differs from tar, which is extracted from coal and is no longer permitted as a building material in Germany. While bitumen comes from crude oil and is chemically stable, the decomposition of bitumen at high temperatures leads to different reactions.