This standard provides a method for calculating the penetration index {'PI) of bitumen from penetrations determined at two different temperatures, or from the softening point of ring and ball and the penetration determined at 25 °C. The standard applies to those bitumens for which the logarithm of the penetration (f, 100 g, 5 s) is approximately a linear function of the temperature f, in the temperature range accessible for penetration.
NEN 3950-1982 history
1982NEN 3950-1982 Bitumen and tar products - Penetration-index (PI) of bitumen