What is Viscosity Grade Bitumen (VG Bitumen)?
Viscosity Grade Bitumen (VG Bitumen) is a high-quality road construction, asphalt production, and waterproofing product. VG Bitumen is refined from crude oil when being processed and graded by its viscosity (capacity to resist flow) at various temperatures, thereby ideal for diverse climates and applications. This handbook outlines VG Bitumen, its grades, applications, and benefits in global infrastructure development.
Understanding Bitumen Viscosity
Bitumen is a black, highly viscous, adhesive construction material. The viscosity, or thickness, determines how it will perform in uses like road construction and roofing. Key determinants of viscosity are:
Temperature: VG Bitumen is liquid at warm temperatures (i.e., asphalt mixing time) but becomes thicker or even solid when cooler.
Shear Rate: When applied or mixed, VG Bitumen loses viscosity and is more easily workable.
Modifiers: Additives or polymers can regulate viscosity to enhance performance, for instance, adhesion or crack resistance.
VG Bitumen is graded according to 60°C (140°F) and 135°C (275°F) viscosity, in compliance with ASTM D3381 and AASHTO M226 standards, for assured global quality.
Viscosity Grade Bitumen is a conformity bitumen grade used in road construction, asphalt pavements, and industrial applications. The viscoelastic property of its kind provides superior strong, elastic binding to aggregate, therefore suitable for durable roads and surfaces. VG Bitumen is available in grades like VG10, VG20, VG30, and VG40, with larger numbers indicating harder bitumen for higher traffic or hot climates.
Typical VG Bitumen Grades
VG10: Ideal for cold climates (below 30°C), penetration range of 80/100. Used in emulsion bitumen and as a substitute for penetration grade 80/100.
VG20: Ideal for cooler or mountainous regions (30–37°C). Ideal for moderately trafficked roads.
VG30: Ideal for temperate climates and heavy traffic. Ideal substitute for penetration grade 60/70.
VG40: Used in high-stress areas (e.g., highways, intersections) with temperatures above 40°C instead of penetration grades 40/50 and 30/40.
VG Bitumen Applications
Road Construction & Surfacing
VG bitumen is used extensively in highway asphalt surfacing, city roads, and country roads.
According to traffic loading and climate:
VG-10: For low-temperature climates and sprayed application.
VG-20: For moderately cold climate roads with medium traffic.
VG-30: In high-temperature climates and heavily trafficked roads.
VG-40: In extremely heavy traffic areas, including expressways and industrial roads.
Hot Mix Asphalt (HMA)
VG bitumen is a key binder in the production of HMA.
It helps bind aggregates together and provides the necessary flexibility and durability.
Surface Dressing
VG bitumen is used for surface dressing (a maintenance treatment where bitumen is sprayed onto the road and then overlaid with aggregates) in low-volume roads.
Bituminous Macadam and Dense Bituminous Macadam (DBM)
Used in base and binder courses of flexible pavements.
VG-30 and VG-40 also receive common usage due to their higher stiffness and rut resistance.
Waterproofing
VG bitumen can additionally be used in basement and roofing applications as a water-resistance protective coating.
Industrial Applications
Used as binder and protective covering in cement industries—e.g., in pipe paints, battery sealants, cement cables insulation, etc.
Airport Runways & Port Pavements
VG-40 bitumen, being stiffer, is utilized in the runways and port areas where heavy loads and stress are experienced.
Benefits of VG Bitumen
Engineering Precision: Viscosity grading tests performance at three temperatures (25°C, 60°C, 135°C) for compatibility between climates.
Increased Durability: viscosity grade Bitumen is resistant to heavy traffic and extreme weather conditions, reducing maintenance costs.
Global Standards: Meets ASTM and AASHTO standards, trusted by Saudi Arabia, UAE, and other contractors.
Efficient Testing: Quality assurance is achieved with only seven tests, which will reduce time and costs.
Limitations of VG Bitumen
Low-Temperature Performance: 25°C grading will not precisely simulate behavior in very cold climates (e.g., Russia).
Testing Costs: Viscosity testing is expensive and time-consuming as compared to penetration testing.
Variability: Some VG grades can perform differently when they are aged, so one has to choose them very carefully.
Why Use viscosity grade Bitumen?
VG Bitumen is high-performance for road construction and roof waterproofing, meeting international market demands like India’s infrastructure projects, Saudi Arabia’s roads, and European urban developments. Its viscosity grading provides a consistent performance in heat and cold conditions, thus the ideal choice for contractors worldwide.
How to Select the Proper Viscosity Grade Bitumen?
To select the proper viscosity grade bitumen based on the IS73 standard, the mean temperature of the field should be in one of the divisions of the following table:
| Grade | Suitable for 7 days Average Maximum Air Temperature ° C |
|---|---|
| VG 10 | < 30 |
| VG 20 | 30 – 38 |
| VG 30 | 38 – 45 |
| VG 40 | > 45 |
Specification of Viscosity Bitumen (ASTM D3381-09)
| Property | Units | AC-10 | AC-20 | AC-30 | AC-40 | Test Methods |
|---|---|---|---|---|---|---|
| Viscosity, 140°F (60°C) | P | 1000±200 | 2000±400 | 3000±600 | 4000±800 | ASTM D-2171 |
| Viscosity, 275°F (135°C), Min | cSt | 150 | 210 | 250 | 300 | ASTM D-2171 |
| Penetration, 77°F (25°C), 100g, 5sec, Min | 0.1MM | 70 | 40 | 30 | 20 | ASTM D-5 |
| Flash point, Cleveland open cup, Min | °C | 219 | 232 | 232 | 232 | ASTM D-92 |
| Solubility in trichloroethylene, Min | %Wt | 99 | 99 | 99 | 99 | ASTM D-2042 |
| Viscosity, 140°F (60°C), Max | P | 5,000 | 10,000 | 15,000 | 20,000 | ASTM D-2171 |
| Ductility, 77°F (25°C), 5cm/min, Min | CM | 50 | 20 | 15 | 10 | ASTM D-113 |
Technical Data Sheet of VG Bitumen (IS 73:2013)
| Property | Units | VG-10 | VG-20 | VG-30 | VG-40 | Test Methods |
|---|---|---|---|---|---|---|
| Penetration at 25°C, 100g, 5sec, Min | 0.1MM | 80 | 60 | 45 | 35 | IS 1203 |
| Absolute viscosity at 60°C | P | 800-1200 | 1600-2400 | 2400-3600 | 3200-4800 | IS 1206 (Part 2) |
| Kinematic viscosity at 135°C, Min | cSt | 250 | 300 | 350 | 400 | IS 1206 (Part 3) |
| Flash point (Cleveland open cup), Min | °C | 220 | 220 | 220 | 220 | IS 1448 [P : 69] |
| Solubility in trichloroethylene, Min | %Wt | 99 | 99 | 99 | 99 | IS 1216 |
| Softening point (R&B), Min | °C | 40 | 45 | 47 | 50 | IS 1205 |
| Viscosity ratio at 60°C, Max | - | 4 | 4 | 4 | 4 | IS 1206 (Part 2) |
| Ductility at 25°C, Min | CM | 75 | 50 | 40 | 25 | IS 1208 |
