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Whats the difference between asphalt and coal tar?

April 26, 2017Asphalt Coal tar

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Whats the difference between asphalt and coal tar?

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Asphalt is derived from crude petroleum. Its an aliphatic or straight-chain hydrocarbon resin. Coal tar is derived from the destructive distillation or coal. It is an aromatic ring shaped hydrocarbon resin. The two are different and generally incompatible. Asphalt is normally lower in cost, can be used on pitched roofs to vertical, has fair resistance to UV degradation and can be left bare or surfaced in a variety of manners, but it has poor resistance to ponding water. Coal Tar can only be used on near to dead level roofs and has poor resistance to UV degradation so it must always be surfaced with a layer of gravel, pavers or vegetation. Coal tar has good resistance to ponding water and exhibits cold flow or self-healing characteristics.