Bitumen grades explained: 60/70 penetration vs VG-30 viscosity grade

How penetration grades and viscosity grades differ, which standards they come from, and how to choose the right one for a road project.

Bitumen is sold under two grading systems, and buyers often mix them up. Knowing which one your project specifies avoids rejected cargoes.

Penetration grades (60/70, 80/100). The grade comes from a needle test. A standard needle sinks into the sample for five seconds at 25 °C under a 100 g load, and the depth is measured in tenths of a millimetre (ASTM D5, EN 1426). A 60/70 bitumen has a penetration between 60 and 70. The lower the number, the harder the bitumen. These grades are common in the Middle East, Africa, Europe and much of Asia, usually under ASTM D946 or EN 12591.

Viscosity grades (VG-10, VG-20, VG-30, VG-40). The grade comes from the viscosity at 60 °C, measured in poise. Roughly, VG-30 sits at 2,400 to 3,600 poise. The system is used mainly in India under IS 73. A higher number means a stiffer binder that holds up better in hot climates and heavy traffic.

Which one do you need? Check the tender or the contract. If it says 60/70, a VG-30 certificate does not satisfy it, even though the two are often close in practice. [Check the exact limits against the current standard before publishing any table.]

What to ask the supplier: the grade and standard, softening point, flash point, ductility, a certificate of analysis for the batch, and the packing (bulk, drums or jumbo bags).

Need a price or a certificate? Request a quote with the grade, quantity and destination port.