Bitumen
Bitumen Production Process
How crude oil becomes a specification binder — distillation, oxidation, blending, and the quality controls that sit between them.
Bitumen is not a manufactured chemical so much as a carefully separated one. The production route determines the molecular make-up of the finished binder, and that in turn decides how it behaves on the road. Understanding the process explains why two products with the same penetration value can still perform very differently.
Step one — atmospheric distillation
Desalted crude is heated to around 350 °C and fed into an atmospheric column. Gases, naphtha, kerosene and gasoil separate by boiling point and leave as side draws. The long residue collecting at the bottom still contains material that would crack if heated further at atmospheric pressure.
Step two — vacuum distillation
The long residue passes to a vacuum column operating at 10 to 100 mmHg. Lowering the pressure lowers the effective boiling points, so vacuum gasoil can be removed without thermal damage to the residue. The short residue drawn from the base of this column is straight-run bitumen, and its hardness is controlled by how deeply the column is cut.
Straight-run production is the preferred route for paving grades because it preserves the natural balance of asphaltenes and maltenes that gives the binder its flexibility.
Step three — air blowing, where required
Harder, more temperature-stable products are made by blowing hot air through the residue at 240 to 300 °C. Oxygen drives dehydrogenation and polymerisation reactions that build larger molecules, raising the softening point while reducing penetration. Fully blown grades serve roofing and industrial work; lightly blown, semi-blown material is used where a slightly stiffer paving binder is needed.
Step four — blending and modification
- Component blending of soft and hard streams to hit a target penetration
- Polymer modification with SBS or APP for elasticity and rutting resistance
- Cutting back with kerosene or naphtha to produce cutback grades
- Emulsification with water and surfactant to produce bitumen emulsions
- Addition of anti-stripping agents where aggregate compatibility requires it
Quality control through the chain
Every production batch is tested for penetration, softening point, ductility, flash point, solubility and loss on heating, with rotational viscosity and RTFO ageing added for performance-graded products. Addam retains sealed reference samples and issues a certificate of analysis tied to the specific batch and shipment, so the material in your tank can always be traced back to the test that cleared it.
