Bitumen is a black-coloured substance that consists of hydrocarbons with a high molecular weight and their derivatives. It is insoluble in water. It is found in solid as well as in the resinous state. It is formed as a result of natural oxidative polymerization of petroleum. On the other hand, artificial bitumen is formed by processing black gold.
Bitumen mixture is an amalgamation of natural, as well as artificial ingredients. It is extensively used in road constructions, road repairs, and industrial constructions like roofing, paint production, insulation pipelines, etc.
A chemical supplier provides bitumen in both forms, natural, as well as artificial.
Importance of bitumen modification or improvement
When used for road construction, bitumen serves the purpose of a binding agent. It binds mineral materials like gravel, sand, etc. to enhance concrete’s hydrophobic properties, as well as to fill the gaps. But, as it is exposed to various agents like solar radiation, temperature fluctuation, air oxygen, traffic load, etc. it gets destroyed and hence, the surface of the road gets damaged prematurely. Bitumen modification is done to prevent this. Modifying bitumen improves its properties making it apt for road construction.
How is bitumen modification done?
There are two ways of enhancing the properties of bitumen. They are:
- Changing the technology used in production
Changing the technology used in producing bitumen demands alteration in the entire production process right from preparation of the raw materials to equipment used for finishing. Every part of the production has to be changed to use this approach. Plus, it incurs heavy charges.
- Directly upgrading the final product: Bitumen modification
Bitumen modification is the approach of choice to enhance the properties of bitumen. Various kinds of modifiers are used for this purpose. The most commonly used bitumen modifiers are thermoplastic polymers, thermoplastic elastomers, rubber, as well as rubber resin.
- Thermoplastic polymers:
They soften as the temperature increases and harden as it drops. The thermoplastic polymers that are used for bitumen modification include polyethylene (PE), polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), thermoplastics and viscoplastic.
- Thermoplastic elastomers:
Thermoplastic elastomers possess elastic properties for adhesive applications. They are available in the form of powders and granules with a chemical supplier.
They are used in the modification of roofing, as well as road bitumen. The commonly used thermoplastic elastomers are styrene-butadiene diblock copolymers (SB), styrene-ethylene / butylene-styrene polymers (CE / BS), styrene-isoprene-styrene polymers (SIS), and styrene-butadiene-styrene polymers (SBS).
- Rubber and rubber resin
When the load is applied, rubber and rubber resin tend to elongate up to ten times. On removal of load, they tend to return to their original state. Owing to this property, they are used to enhance the properties of bitumen.
The common rubber modifiers used in the process of bitumen modification are ethylene-propylene polymers, styrene-butadiene rubber (SBR), and butyl rubber.
The process of bitumen modification is carried out in colloid mill where bitumen is mixed with the polymer. It grinds the components and makes a homogenous mixture.
Advantages of bitumen modification
Bitumen modification has many benefits. The final product that comes out as a result of bitumen modification possesses the below-mentioned characteristics:
- It binds excellently with the mineral materials
- It is elastic, as well as flexible, at low temperature. It does not deform or change in shape when the temperature rises.
- It is resistant to temperature variation. It amazingly bears fatigue loads that occur as a result of temperature variation.
- It readily imbibes mechanical, as well as thermal stresses, in the pavement’s asphalt layers.
- It has wide plasticity, as well as the service temperature interval.
- It possesses excellent mechanical properties.
- It is hard.
Bitumen is widely used in various industries. A little modification makes it more effective in all its applications.