Penetration Graded Bitumen
Penetration Graded 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 graded bitumens normally state the penetration range for a grade eg 50/70. Other tests are used to classify the bitumen for specification purposes, such as softening point, solubility, flash point etc.
Viscosity graded bitumen
Bitumens are also graded and specified by their viscosity at a standard temperature (typically 600C). Specifications for viscosity graded bitumens normally give the normal viscosity prefixed by a V e.g. V15000. We usually do not supply viscosity graded bitumen in our standard range, but can supply on special client requisitions.
Oxidized Bitumen Grades
Passing air through bitumen at elevated temperature can be used to alter its physical properties for certain commercial applications. The degree of oxidation can range from very small, often referred to as air rectification, or semi blowing which only slightly modifies the bitumen properties, through to “full” blowing whereby the properties of the bitumen are significantly different to penetration grade bitumens. Nomenclature and grading for the oxidized bitumen products is based on a combination of the temperature at which the bitumen reaches a certain “softness” when being heated up as expressed by the ring and ball softening point test, and the penetration value.
