1. Tar And Bitumen

Tar: No longer used for road construction because of its *Carcinogenic Effect and high temperature susceptibility. Presently, roads are mostly constructed using Bitumen.

Reason For Confusion Between Tar and Bitumen: Both have black color and both have very good Waterproofing and adhesion property.

Production Method:

Tar→ From Destructive Distillation (Burning in Specific Condition of Temperature, Without Presence of Oxygen) of Bituminous Coal

Bitumen→ Obtained From Refining Process (Fractional Distillation) of Crude Oil (A Petroleum Product)

* For Manufacturing of Tar, Coal is Burnt Without Presence of Oxygen. This induces formation of specific molecules called Polyclic Aromatic Hydrocarbons [PAH] which are carcinogenic.

(PAH represent 20–30% Composition of Tar. That’s the Reason the Use of Tar is Banned in Most Countries.)

[PAH is also present in Bitumen. But only approximately 0.01%. So, it is not carcinogenic]

2. Bitumen and Asphalt:

 In India and Europe, Asphalt = Aggregates + Bitumen i.e. Paving Material

In America, Asphalt = Bitumen (Black Viscous Liquid)