Bitumen penetration grade 85/100 means the penetration value is in the range 85 to 100 at standard test ,Bitumen 85/100 is a standard penetration grade bitumen usually used as a paving grade bitumen suitable to be used in producing hot mix asphalt for road construction and production of asphalt pavements. This grade of Bitumen is mainly used in the manufacture of hot mix asphalt for bases and wearing courses. Penetration Grade bitumens are specified by the penetration and softening point test. Designation is by penetration range only. The penetration grade bitumens have a thermoplastic property which causes the material to soften at high temperatures and to harden at lower temperatures. This unique temperature/viscosity relationship is important when determining the performance parameters such as the adhesion, rheology, durability and application temperatures of bitumen.