The so-called refinery bitumen is obtained from the aeration of vacuum baton in the distillation tower and is divided according to viscosity (viscosity). This type of bitumen is mostly used in road construction, insulation, construction and also production of liquid bitumen.

In the classification based on bitumen viscosity, they are classified according to the amount of absolute viscosity at 60 یا C or kinematic viscosity at 135 سان C. > The temperature of 60 and 135 degrees Celsius is the temperature of the road surface in summer and the temperature of mixing asphalt, respectively. AC-30 bitumen is more suitable for temperate climates