Bitumen is a black, semi-solid or liquid substance with high viscosity produced by the non-destructive distillation of crude oil during petroleum refining. The core industry using bitumen is road construction (asphalt) and another significant field is the building industry (roofing membranes, water-proofing felts).
MOL’s bitumens satisfy the requirements specified by the standards completely, product development is realized taking into consideration the European directions and the industry specific needs. In our product portfolio wide range of high quality and complex products for all road construction and building industry purposes can be found.
Bitumen is loaded at minimum 170 degrees and transported mainly by road tank cars, but also rail deliveries and container fillings are part of the portfolio.
Types of bitumen
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.
Building bitumens produced by MOL fully satisfy the limit values specified in the test methods of conventional bitumens. Furthermore, they increase the durableness of the roofing and water proofing felts made from them and guarantee appropriate resistance against aging.
Modified bitumen products are more durable and are primarily used on roads subjected to high traffic loads. Compared to road bitumens these types have more flexible qualities, therefore can bear temperature changes on a wider scale.
In line with the principle of reuse and recycle, MOL and the University of Pannonia (Veszprém) have developed chemically stabilized rubber bitumen as a new type of road construction binder through several years of research and development. Rubber bitumen received a Construction Technical Permit for use in transport construction in 2008 (ÉME 13/2008). The product and the manufacturing process were patented in 2009 (HU 226481).
Test-type road construction and asphalt testing in recent years have demonstrated significantly better quality than normal bitumen and excellent user properties for rubber bitumen, in line with international experience.
The product is of significant national economic value, as the environmentally friendly recycling of used tires is achieved in a value-creating way.
The main advantages of using rubber bitumen:
- A longer service life is achieved compared to a normal bituminous road.
- Its fatigue properties are excellent, so it is less likely to crack the asphalt road.
- It results in a higher load capacity and a lower tendency to tramline.
- Its excellent adhesion to the mineral reduces the chance of pits forming.
- Longer life and better resilience result in lower maintenance costs.
- Less driving noise can be achieved
- Greater traffic safety due to better drainage.
The production and application of rubber bitumen in road construction not only improves the quality of asphalt roads compared to asphalt roads built with normal bitumen, but also offers a solution for the environmentally friendly processing and recovery of waste tires.