INDIAN GEOGRAPHY

Detailed explanation-1: -Coal tar is used in metalling of roads.

Detailed explanation-2: -Metalled roads are constructed with cement, concrete, or bitumen of coal whereas unmetalled roads are natural pathways made primarily of mud. Metalled roads can be used in the rainy season, whereas unmetalled roads go out of use in the rainy season.

Detailed explanation-3: -Bitumen, a petroleum product, is used in place of coal-tar for metalling the roads. It is a very good adhesive. It sticks well to the sub layers. Bitumen is a black, oily, viscous material that is a naturally occurring organic byproduct of decomposed organic materials.

Detailed explanation-4: -Synthetic Modified Bitumen Coal, for Road Construction.

Detailed explanation-5: -Coal tar is a ready source of asphaltenes needed in asphalt production. Coal tar pitch itself, however, is unsuitable for making road-paving asphalt, since the resulting material has low ductility, high temperature sensitivity, and low resistance to wear.