Viscosity Grade Bitumen (Asphalt) is a standard grade Bitumen usually used as a Paving Grade Bitumen suitable for road construction and for the production of asphalt pavements with superior properties. This grade of Bitumen is mainly used in the manufacture of hot mix asphalt for bases and wearing courses and possesses characteristics and qualities unique and quite different from other agents. They achieve very flexible and tenacious connections with other materials due mainly to viscoelastic response of bitumen, which behavior depends on how fast charges are applied.
Viscosity Grade Bitumen is petroleum grade bitumen, manufactured from fractional / vacuum distillation of crude oil, which practical appliance and behavior vary according to its temperature. The Bitumen supplied is produced from vacuum residue (short residue) feedstock.
Viscosity Grade bitumens are specified by the methods described in ASTM Standard D3381-09 and AASHTO M226-80 (2008). Viscosity Graded specifications cover bitumen (asphalt) graded by Viscosity at 60°C (140 °F).
There are two methods of grading:º
- Standard Viscosity Grade Bitumen (AC-Grades), in which the Viscosity of the standard bitumen (asphalt) is measured at 60 ºC (140 ºF).
- RTFOT Viscosity Grade Bitumen (AR-Grades), in which the Viscosity of bitumen (asphalt) is measured at 60 °C (140 °F) after the roll on thin film oven test.
All types of viscosity grade bitumen include VG10, VG20, VG30, and VG40.