Penetration grade bitumen
Penetration Grade Bitumen is classified by the depth to which a standard needle will penetrate under specified test conditions. This “pen” test classification is used to indicate the hardness of bitumen, lower penetration indicating harder bitumen. Specifications for penetration grade bitumen normally state the penetration range for a grade, e.g. 60/70. Other tests are used to classify the bitumen for specification purposes, such as softening point, solubility, flash point etc.