Penetration graded bitumen is a classification of bitumen based on its hardness or consistency, which is measured by the depth (in tenths of a millimeter) that a standard needle penetrates vertically into a sample of bitumen at a temperature of 25 degrees Celsius under a specific load for a specific duration. This is known as the penetration test, standardized by ASTM D5 or EN 1426. The penetration grade indicates the stiffness of the bitumen, which is a key factor in its suitability for different paving and climatic conditions.

Lower penetration grade bitumen, like 40/50, signifies harder bitumen which is suitable for warmer climates as it softens less in the heat. Higher penetration grades, such as 100/120 or 200/300, yield softer bitumen typically used for colder regions to prevent cracking due to the material’s enhanced ability to expand and contract with temperature changes.

For more information about penetration graded bitumen, you can visit the following web pages:

1. The Asphalt Institute: A leading international organization that provides technical knowledge about asphalt and specifically penetration graded bitumen. Although access to standards might require a membership or purchase, their general resources provide valuable information about bitumen. Their website is:

Welcome

2. The Energy Institute (EI): The EI provides a range of technical documentation, including specifics on various types of bitumen, publications, and articles on research and development within the energy sector, some of which relate to bitumen and its applications. You can explore more here:
https://www.energyinst.org/