Bitumen is the adhesive used for asphalt toppings and bituminous layers of roadway structures, jointing the inorganic components of asphalt (sand, broken stone, ballast, most frequently limestone dust).
Important features of our bitumen products are the following:
- Having wide temperature range of usability. (Do not become fragile at low temperatures and do not undergo structural changes at the temperature of hot asphalt production.)
- Suitable for the laying of durable asphalt topping, age only at a slow rate.
In the oil refinery, bitumen suitable for various uses can be produced from the heavy product of vacuum distillation. The bulk of bitumen’s weight is composed of high molecular paraffinic, naphthenic, aromatic combinations of hydrocarbons, but many molecules contain heteroatoms as well like: sulphur, nitrogen, oxygen, and metal. There is a continuous transition between the molecular size and the chemical nature of the compounds that make up bitumen.
Bitumens can be divided into groups of asphaltene and maltene (saturated, aromatic, resinous) substances with specific chemical and physical properties by means of a group identification method. Asphaltenes form the backbone of bitumens, so the characteristic properties of bitumens (e.g., heat sensitivity, viscosity, and partially colloidal structure) depend on this group of compounds.
In terms of the elemental composition of bitumen, it is 80-85% carbon, 9-10% hydrogen and contains various amounts of heteroatoms. The amount of oxygen can vary from 2 to 8%, depending on the origin and production technology, and the sulfur content can range from a few tenths of a percentage to 7%, depending on the origin.
Bitumen is a viscous or viscoelastic material depending on the test temperature. Upon heating, it gradually softens and then becomes liquid. Bitumen with viscoelastic properties over a wide temperature range can be tested by rheological measurements. Rheological characterization allows performance-based classification of bitumens.
