BITUMEN

Bituminous materials are used for road construction, roofing, waterproofing, and other applications. For the main application, which is road construction, the major concerns, as with concrete, are cost and durability.

Production

Bitumen is made from crude oil by distillation. The crude oil is vaporised and then condensed in a distillation tower, with the lightest components (those with the lowest boiling points) condensing nearest the top. The main components are:

Top:

    Petrol (gasoline),

    Kerosene (paraffin),

    Diesel oil,

    Lubricating oil.

Base:

    Base bitumen.

By mixing base bitumen with lighter oil, different grade bitumens are produced. If increased demand for lighter oils means that more bitumen is being produced that is required, it can be “cracked” to break up the large molecules, and produce more light oils. This increases its value.

Properties: 

• Most bitumens are colloidal in nature.
• Bitumen are thermoplastics.
• They have no specific melting, boiling or freezing point.
• Bitumens are insoluble in water.
• They are highly impermeable to the passage of water.
• They are generally hydrophobic. ...
• Bitumen oxidises slowly.

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