Viscosity Grade Bitumen is a standard grade Bitumen, manufactured from a fractional / vacuum
distillation of crude oil, which practical appliance and behavior varies according to its temperature.
This grade of bitumen is mainly used in the manufacture of hot mix asphalt suitable for road construction, the production of asphalt pavements, roofing, and industrial processes with superior properties.
This type of bitumen has a thermoplastic property which causes the material to soften at high temperatures and to harden at lower temperatures.
The viscosity grading system is more rational than the penetration grading system. Some countries, mainly India, use this type of bitumen. Bitumen is graded based on absolute viscosity at 60 ºC or kinematic viscosity at 135 ºC which are the temperature of the road surface in summer and the temperature of asphalt mixing, respectively.
This type of bitumen is divided as follows:
Grades Minimum of Absolute
Viscosity, Poise@ 600°C
Approximate penetration grade