Viscosity Grade Bitumen (VG Bitumen) is a refined petroleum binder classified based on its absolute viscosity at 60°C and kinematic viscosity at 135°C, in accordance with IS 73:2013, ASTM, and EN standards.
Unlike penetration-graded bitumen, VG Bitumen provides a performance-oriented and scientific classification that reflects actual behavior during mixing, laying, compaction, and service life.
VG grading was introduced to overcome limitations of penetration grading, especially in regions with extreme temperatures, heavy axle loads, and high traffic density.
Common Viscosity Grades
VG-10
VG-20
VG-30
VG-40
Manufacturing & Refining Process
Vacuum Distillation:
High-boiling residues are extracted after removal of lighter hydrocarbons.
Controlled Blending & Oxidation:
Residues are blended and mildly air-blown to achieve precise viscosity values.
Viscosity Calibration:
Adjusted to meet absolute viscosity @60°C and kinematic viscosity @135°C limits.
Batch Testing & Certification:
Each batch is tested as per IS 73, ASTM D4402, ASTM D2171, EN 12596.
Why Viscosity Grading Is Superior
Direct correlation with rutting resistance and load-bearing capacity
Better performance prediction at actual pavement temperatures
Reduced variability and improved quality control
Higher resistance to temperature-induced cracking and deformation
Preferred by modern highway authorities
Key Technical Characteristics
Temperature-Based Performance:
Viscosity @60°C ensures high-temperature stability, while viscosity @135°C ensures workability.
Superior Rutting Resistance:
High VG grades resist deformation under heavy loads and slow-moving traffic.
Improved Temperature Susceptibility:
Lower bleeding at high temperatures and reduced cracking at low temperatures.
Enhanced Workability:
Better aggregate coating, reduced fuel consumption, uniform compaction.
Aging & Oxidation Resistance:
Lower hardening rate, longer pavement life.
Grade-Wise Mechanical & Physical Properties
VG-10 Bitumen
| Property | Typical Value |
|---|---|
| Viscosity @60°C | 800 – 1200 Poise |
| Kinematic Viscosity @135°C | ~250 cSt |
| Softening Point | 40 – 47°C |
| Ductility @25°C | >75 cm |
| Typical Use | Cold regions, spray works |
VG-20 Bitumen
| Property | Typical Value |
|---|---|
| Viscosity @60°C | 1600 – 2400 Poise |
| Kinematic Viscosity @135°C | ~300 cSt |
| Softening Point | 45 – 52°C |
| Ductility @25°C | >50 cm |
| Typical Use | Moderate climates |
VG-30 Bitumen
| Property | Typical Value |
|---|---|
| Viscosity @60°C | 2400 – 3600 Poise |
| Kinematic Viscosity @135°C | ~350 cSt |
| Softening Point | 47 – 55°C |
| Ductility @25°C | >40 cm |
| Typical Use | High-traffic highways |
VG-40 Bitumen
| Property | Typical Value |
|---|---|
| Viscosity @60°C | 3200 – 4800 Poise |
| Kinematic Viscosity @135°C | ~400 cSt |
| Softening Point | 50 – 60°C |
| Ductility @25°C | >25 cm |
| Typical Use | Heavy axle loads, airports |
Climate & Traffic Suitability Guide
| VG Grade | Climate | Traffic Condition |
|---|---|---|
| VG-10 | Cold | Light to Moderate |
| VG-20 | Mild | Moderate |
| VG-30 | Hot | Heavy |
| VG-40 | Very Hot | Very Heavy / Slow |
Available Supply Forms
Bulk Tankers
Steel Drums (150–180 kg)
Poly Bags / Jumbo Bags
IBC Containers
Storage & Handling Guidelines
Storage temperature: 130–160°C
Avoid prolonged overheating
Use insulated storage tanks
Prefer gentle agitation over direct heating
Applications of VG Bitumen
Road Construction: HMA, DBM, BC, tack & prime coats
Industrial: Waterproofing, roofing, paints, mastic asphalt
Heavy Infrastructure: Airports, ports, bridges, container yards
Advantages of VG Bitumen
Scientifically graded for real-world performance
Higher load-bearing capacity
Reduced maintenance cycles
Compatible with modern paving technologies
Widely accepted by national & international standards