Bitumen Grade Equivalence Across Grading Systems
How penetration, viscosity, performance and Chinese road grades relate to one another, what each system actually measures, and why the correlation is a starting point for discussion rather than a substitution licence.
Indicative equivalence across the four systems
Read across the row for the closest counterpart in each system. Read the caveat below before using any of it in a tender.
| Penetration | Viscosity (IS 73) | Performance | Chinese (JTG F40) | Character |
|---|---|---|---|---|
| 20/30 | — | — | — | Hard, high modulus and industrial |
| 30/40 | VG-40 | PG 70-10 | No. 30 | Hard, hot climate paving |
| 40/50 | VG-40 | PG 70-10 | No. 50 | Hard paving |
| 50/70 | VG-30 | PG 64-22 | No. 70 | General paving, European reference |
| 60/70 | VG-30 | PG 64-22 | No. 70 | The global export default |
| 70/100 | VG-20 | PG 58-22 | No. 90 | Soft, cooler climates |
| 80/100 | VG-10 | PG 58-22 | No. 90 | Soft paving |
| 85/100 | VG-10 | PG 58-22 | No. 90 | South Asian standard soft grade |
| 120/150 | — | PG 52-10 | No. 130 | Very soft, cold climate and feedstock |
| 200/300 | — | — | — | Softest, almost entirely feedstock |
Why the four systems are not interchangeable
Penetration grading
One consistency reading: needle penetration at 25 °C under 100 g for 5 s. Simple, century-old, and silent on how the binder behaves at pavement temperature or after ageing.
Viscosity grading
Absolute viscosity at 60 °C, the temperature a hot pavement actually reaches, plus kinematic viscosity at 135 °C for mixing. Closer to service conditions than penetration, and the basis of Indian procurement.
Performance grading
Rheology at both service extremes, measured on original binder and after two ageing simulations. The only system that certifies low-temperature cracking resistance explicitly.
Chinese road grades
Penetration-based, designated by number, with additional requirements layered on for climate zone and traffic class within the national road specification.
What changes if you move one grade
Where a tender permits an alternative, this is what actually changes in the field.
| Change | Effect at high temperature | Effect at low temperature | Effect on laying |
|---|---|---|---|
| One grade harder | Better rutting resistance | Higher thermal cracking risk | Higher mixing and compaction temperatures needed |
| One grade softer | Higher rutting and bleeding risk | Better crack resistance | Lower working temperatures, wider compaction window |
| Adjacent standard, same consistency | Usually none | Usually none | None, but the certificate may not satisfy the tender |
| Polymer modified equivalent | Substantially better | Usually better | Higher temperatures, agitated storage required |
Grade substitution is a decision for the specifying engineer or the client, never for the supplier. Any change should be agreed in writing before shipment, because it affects the paving contractor’s working window as well as the pavement’s design life.
Equivalence questions buyers ask
What penetration grade is equivalent to PG 64-22?
Penetration grade 60/70 is the correlation most often quoted, and VG-30 under IS 73 sits in the same region. None of the three is a substitute for the others. PG 64-22 carries verified rheology at 64 degrees, at the intermediate temperature after pressure ageing, and at minus 12 degrees on the bending beam. A 60/70 certificate establishes none of that, so where a contract names a performance grade only an AASHTO M320 certificate satisfies it.
Is VG-30 the same as bitumen 60/70?
They overlap in consistency and are frequently offered against one another, but they are graded on different properties. VG-30 is defined by absolute viscosity at 60 degrees and kinematic viscosity at 135 degrees under IS 73; 60/70 is defined by needle penetration at 25 degrees under ASTM D946 or EN 12591. A binder can satisfy one and miss the other, and Indian tenders written to IS 73 will not accept a penetration certificate.
What is Chinese No. 70 asphalt?
A penetration-based road grade under JTG F40, where the number refers to the penetration band in the same way European and ASTM grades do. No. 70 corresponds broadly to 60/70 and No. 90 to 80/100. As with every cross-system comparison the correlation is indicative; Chinese tenders written to JTG F40 should be answered with a certificate issued against that standard where the specifier requires it.
Why is there no exact conversion between grading systems?
Because they measure different physical properties at different temperatures. Penetration grading takes one consistency reading at 25 degrees. Viscosity grading measures flow at 60 and 135 degrees. Performance grading measures rheology at both service extremes and after two ageing simulations. A single number in one system cannot encode what another system tests, so any conversion table is a starting point for discussion rather than a substitution licence.
Can a supplier substitute a neighbouring grade without asking?
No. Grade substitution is the specifying engineer or client decision, never the supplier decision. Moving one grade harder reduces low-temperature crack resistance; one grade softer reduces rutting resistance at the top of the range. Both changes shift the mixing and compaction window, which affects the paving contractor as well. Any substitution should be agreed in writing before shipment.
Other technical references
Not sure which grade your tender needs?
Send the specification clause or the tender extract and the matching grade, the certificate it would be issued against, and the packing options come back with the offer.