For most projects, bitumen grade selection comes down to two variables: climate and traffic load. Soft bitumen ruts in hot climates; hard bitumen cracks in cold ones. This guide is here to get you to the right grade quickly.
What does a penetration grade mean?
The penetration test measures how far a standard needle sinks into bitumen at 25 °C under a 100 g load in 5 seconds, expressed in tenths of a millimetre. "50/70" means the needle sinks between 5.0 and 7.0 mm.
The higher the number, the softer the bitumen. 50/70 is medium-hard, 160/220 is distinctly soft. Softness means flexibility at low temperature; hardness means holding shape at high temperature.
Which grade, for which conditions?
| Grade | Climate | Traffic | Typical application |
|---|---|---|---|
| 50/70 | Hot – temperate | Heavy | Motorways, arterial roads, airport runways |
| 60/70 | Hot – temperate | Medium – heavy | Dual carriageways, urban arterials, industrial floors |
| 70/100 | Temperate – cold | Low – medium | Rural roads, base layers, maintenance mixes |
| VG 30 | Hot | Heavy commercial vehicles | Motorways, heavy-load corridors (Indian standard) |
| 160/220 | Cold | Low – medium | High thermal cracking risk areas, base–binder layers |
Penetration or viscosity grading?
Two classification systems exist and usage varies by region. Penetration grades (50/70, 70/100) are common in Europe, the Middle East and Africa, based on EN 12591. Viscosity grades (VG 10, VG 30, VG 40) are used in South Asia, particularly India, and are defined under IS 73.
The two are not directly convertible, but in practice VG 30 is treated as performing in a similar range to 60/70. Whichever system the specification names, that is the system the grade should be requested in.
Information to share when requesting a quote
- Project geography and annual temperature range
- Expected traffic load and heavy vehicle share
- Standard named in the specification (EN 12591, IS 73, ASTM D946, etc.)
- Required tonnage and delivery schedule
- Destination port and discharge facilities
Common mistake: Looking only at the penetration value. Softening point, ductility and penetration loss after heating also determine performance. Ask for all of these on the certificate of analysis — a product may match on penetration alone and still not behave as expected in the field.