High temperature in laying bituminous pavement

Generally bituminous materials are also broadly categorized into two types viz bitumen McAdamsand hot-rolled asphalts. At the time of compaction, increase of temperature causes the reduction of viscosity of binder. The binder behaves as a lubricant among aggregates particles since it is mobile in a fluid state under high temperatures. Internal resistance between the bituminous materials is drastically decreased resulting in the formation of a mixture with better aggregate interlock.

Bitumen McAdamsmostlycomprises continuously graded aggregates. Compaction of this type of bituminous material is eased with an increase of mix temperature as lubricating effect of decreased viscosity of binder helps in the rearrangement of aggregates.  

Aggregate of hot-rolled asphalt aren't well graded. With a rise in mixing temperature, binder would stay unset and mixture has little resistance to compaction.