Performance Grade Bitumen (PG)
Performance Grade (PG) bitumen is graded based on its performance characteristics at various
temperatures.
The Long-Term Pavement Performance (LTPP) program has developed a specific algorithm to estimate pavement temperature based on the ambient air temperature. This calculation is used to determine both the highest and lowest expected pavement temperatures. Subsequently, bitumen with performance characteristics suitable for that temperature range is chosen.
PG is the latest standard of the day. It is a comprehensive scientific approach that studies the mechanical properties of bitumen.
In PG bitumen, the classification is done based on understanding the behavior of the bitumen and its functional characteristics, so that in this classification, different characteristics against cracking and deformation due to cold and heat and fatigue and predicting the hardening of the bitumen in the factory It is taken into consideration when preparing asphalt. Also, the amount of traffic and the passage of time and speed of loading on the road are considered.
Adjustments are applied to the PG grade of asphalt cement, taking into account traffic conditions and volumes, with the aim of improving the pavement’s design life.
Among the most important categories of performance grade bitumen are:
- PG 64-22
- PG 46-22
- PG 52-28
- PG 58-16
- PG 58-22
- PG 70-10
- PG 76-10
- PG 82-10
The PG grading system comprises two numbers. For example in PG 64-22, the first number (64) signifies the high pavement temperature in degrees Celsius, and the second number (-22) indicates the low pavement temperature.
PG 64-22 is a common PG bitumen grade used in many moderate to warm climates and it is alternative to the 60/70 penetration grade bitumen. Also PG 58-22 has almost the same performance as the 85/100 penetration grade bitumen.