Penetration Grade Bitumen ( like Bitumen 60-70) is classified using penetration property. It is a kind of bitumen, which is provided during the process of oxidation of vacuum bottom (the bitumen Definition: production feed-stock that derives from distillation tower residue in vacuum oil refineries) at bitumen production units in a manner that its penetration point (kind of test to indicate the hardness of bitumen) becomes between 60 70.