Penetration Grade Bitumen

Penetration grade bitumen is one of the most common types of bitumen used in road construction. It is a petroleum-grade bitumen that is manufactured at different viscosities through fractional or vacuum distillation of crude oil.This refinery bitumen consists of a wide category of bitumen, which includes more than 5 subgrades: bitumen 30/40, 40/50, 50/70, 60/70, 85/100, and 100/120. These subgrades differ in their level of stiffness—the lower the number, the harder the bitumen is. The level of stiffness of each subgrade is determined through the penetration method.In this process, an expert pierces the bitumen while it is being maintained at 25ºC using a standard needle and measures the speed of penetration. For example, bitumen 30/40 has a penetration of between 30 to 40 mm, while the penetration of bitumen 60/70 is between 60 to 70 mm.