Viscosity Grade Bitumen
Viscosity Grade Bitumen is called a grade of refinery bitumen obtained from the vacuum aeration of the distillation tower and divided according to their viscosity. The most common use of Viscosity Grade Bitumen is in road construction, insulation, building construction and liquid bitumen production. In terms of place of use, VG30 bitumen is more suitable for temperate climates.
In the classification based on the Viscosity Grade Bitumen according to the value of absolute viscosity at 60°C or kinematic viscosity at 135°C, the classification and direction of each of them have been determined by specific technical standards. Absolute viscosity is expressed in poise and kinematic viscosity is expressed in centi-Stokes. Classification and characteristics of pure bitumen are reported in AASHTO-M226 and ASTM-D3381 standards.
Viscosity is a fundamental property of bitumen that determines how the material behaves at a certain temperature or a temperature range. The basic unit of Viscosity Grade Bitumen is pascal second (Pa.s). The absolute viscosity or bitumen dynamics measured in pascal seconds is the shear stress applied to the sample in pascals divided by the shear rate per second (1 Pa = 10 Poise). Absolute viscosity of bitumen can be measured by sliding plate viscometer.
Viscosity Grade Bitumen can also be expressed with the unit of square meters per second or with the more common unit of square millimeters per second, where one square millimeter per second is equal to one centistokes. These units are related to kinematic viscosity.
Viscosity grade bitumen
The higher the temperature, the harder the bitumen is. In the viscosity grade, the viscosity test of Viscosity Grade Bitumen is measured at 60 and 135, which is the temperature of the road surface in summer and the temperature of mixing asphalt, respectively.
The degree of penetration at a temperature of 25 degrees, which is the average annual temperature of the asphalt coating,Viscosity Grade Bitumen is also specified in the specifications of this bitumen standard.
Viscosity Grade Bitumen are classified based on the viscosity test results. Viscosity Grade Bitumen, which has many uses in areas like India, will soon replace penetrating bitumen in these areas.