Bitumen is a key ingredient in creating flexible pavement roads. It’s a mixture of various organic materials such as vegetation, dead insects, and algae. Derived from petroleum through distillation, bitumen is composed of aromatic hydrocarbons and is typically found in a solid or semi-solid state, appearing black or brownish-black.
Composition of Bitumen
Breaking it down, bitumen comprises three elements: carbon (87%), hydrogen (11%), and oxygen (2%). The presence of different organic matter, especially in areas with abundant vegetation, contributes to its formation.
Natural Formation of Bitumen
Bitumen naturally occurs where there’s abundant vegetation. It forms from the remains of dead plants, insects, algae, and other organic matter. The pressure and heat beneath the earth transform these remains, deposited in water bodies like lakes, into bitumen. Additionally, alternate sources include sugar, molasses, starch from potatoes, corn, rice, and waste materials via fractional distillation.
Exploring Bitumen’s Properties
- Black in color, bitumen is viscous in both its natural and artificial states.
- Specific gravity stands at 1.09.
- Adhesive in its liquid state, bitumen prevents water penetration, making it highly impermeable.
- Chemically inert, bitumen exhibits stability in various conditions.
Versatile Uses of Bitumen
- Flexible Pavements for Roads: Bitumen is primarily used in road construction, creating what is known as a flexible pavement.
- Waterproofing: Its impermeable nature makes it suitable for sealing leaky joints in roofs.
- Damp-Proof Course (DPC): Applied in walls, basements, tanks, swimming pools, and urinals.
- Historical Sealing Agent: Previously employed for sealing boats and baskets.
Introducing Tar: A Carbon-Rich Liquid Substance
Tar, similar to bitumen, is a liquid with a high carbon content. Its viscosity, temperature sensitivity, and affordability distinguish it from bitumen.
Formation of Tar : Tar, in its various forms, is derived differently. Two commonly used varieties are coal tar (from petroleum) and wood tar (from vegetation).
Tar’s Practical Applications
- Road Pavements: Used akin to bitumen in road construction.
- Roofing Material: Applied in creating roofs.
- Sealing Agent: Employed to seal boots and roof tiles.
- Wood Preservative: Coal tar serves as a preservative for wood.
Distinguishing Bitumen from Tar
- Source of Origin: Bitumen is derived from coal and oil, while tar comes from wood, petrol, and coal.
- Physical State: Bitumen is solid or semi-solid, whereas tar is in liquid form.
- Natural Occurrence: Bitumen occurs naturally; tar is artificially produced through distillation.
- Cost: Bitumen is relatively costlier, while tar is a more economical option.
- Temperature Sensitivity: Bitumen is less sensitive to temperature changes, unlike tar.
- Durability: Bitumen is highly durable, whereas tar is comparatively less durable.
- Specific Gravity: Bitumen has a lower specific gravity; tar possesses a higher specific gravity.
