What does the second number (22) in the PG 67-22 classification indicate?

The second number in the PG 67-22 classification denotes the average low temperature that the asphalt binder can withstand without becoming brittle. Specifically, this value is represented in degrees Celsius.

In the case of PG 67-22, the "22" indicates that the binder is designed to perform well at temperatures as low as -22 degrees Celsius. This classification helps in selecting the appropriate asphalt for different climate conditions, ensuring that the material maintains its necessary properties during colder weather without cracking or losing its structural integrity.

Understanding this classification is crucial for engineers and contractors when deciding which type of asphalt binder to use based on the expected temperature range of the location where the asphalt will be applied.