Performance Grade Bitumen (PG Bitumen) is a special type of bitumen that is rated based on its ability to perform under specific conditions. This classification system is founded on a comprehensive understanding of bitumen’s properties and behavior and allows for the selection of the most suitable bitumen for a particular project. Key factors that are considered when evaluating the performance of bitumen include resistance to deformation, cracking due to cold, fatigue cracking, and the ability to predict how bitumen will harden over time, both in the asphalt factory and under varying temperatures.
Each type of bitumen is distinguished by two values, with the positive value representing the median temperature of the highest pavement temperature over the last seven days, while the negative value represents the lowest pavement temperature in degrees Celsius. For instance, a PG Bitumen may be used in an environment where the average maximum temperature is 52 and the minimum temperature is -40. In order to ensure that the right grade of PG Bitumen is chosen for a paving project, factors such as traffic volume, speed, and pavement structure must be taken into account.
We at Skytrade Global Enterprises Limited, we produce and distribute various grades of high-quality PG Bitumen, both from Iran and the UAE, to countries all around the world. Our production process involves the latest technology and strict quality control measures, allowing us to offer only the best PG Bitumen to our clients.
The concept of PG Bitumen has its roots in the Strategic Highway Research Program (SHRP) in the United States. In a project that ran from 1987 to 1993, the SHRP aimed to improve the performance and durability of asphalt roads and enhance safety. The program focused on improving the bitumen performance standards and developing a system for evaluating and measuring bitumen’s long-term performance in asphalt. This program was the precursor to the performance grade bitumen (PG Bitumen) system, which allows for the analysis and projection of bitumen performance by simulating real-world conditions in the laboratory.
The Super Pave grading system classifies binders as PG Bitumen based on their performance at different temperatures. The goal of selecting and grading an asphalt binder is to ensure that it has the appropriate properties for the specific environment in which it will be used. In order to determine the physical properties of the binder, a battery of tests is conducted, which are directly related to how well the binder performs during paving.
The Long-Term Pavement Performance (LTPP) offers a controlled way of computing the pavement temperature based on the air temperature, allowing for the selection of the most suitable bitumen for the conditions. Penetration and viscosity grading methods, which were previously used to define asphalt binders, were shown to be unsatisfactory, leading to the development of new specifications and binder tests as part of the Superpave research. These tests aim to solve pavement performance issues such as heat cracking, rutting, and fatigue cracking.
The PG system uses a standard set of tests to assess the qualities of asphalt binders, with the results being used to determine which binder is best suited to a particular environment. The system takes into account the aging difficulties and expected climatic conditions, as well as the unique climatic conditions in the area of application. This results in a more comprehensive and accurate assessment of the suitability of an asphalt binder for a specific project, compared to the previous penetration and viscosity grading methods.
List of Perfomance Grade Bitumen Applications as per Specifications
Performance grade bitumen has several applications in road construction and maintenance. Each grade has unique properties that make it suitable for specific projects.
PG 52-28 is commonly used in new construction and road maintenance paving, as well as in dense-graded and open-graded Hot Mix Asphalt (HMA). This solution can also be used to seal cracks in paving and the margins of the paving. Additionally, it is used in membrane spraying, such as on bridge decks and pavement protection membranes.
PG 58-22 is used in dense-graded and open-graded Hot Mix Asphalt (HMA) paving, as well as in road construction, spraying, and crack sealing applications. PG 58-28 is used for the same applications and is often used in very cold climates.
PG 58-34 is used on higher elevation roads and is primarily used in the manufacture of Hot Mix Asphalt (HMA). It can also be used to seal the margins of new and old paving, as well as to fill cracks.
PG 58-40 is generally employed in high elevation areas and is used in the manufacture of Hot Mix Asphalt (HMA). It is mainly used for crack treatment and sealing.
PG 64-22 is primarily used in paving for new construction and pavement treatment projects, as well as in dense-graded and open-graded Hot Mix Asphalt (HMA). It is suitable for sealing and crack treatment, and it can be used in spray treatments for bridge decks and pavement protection layers. This grade is observed to exhibit less tenderness than lower viscosity/softer asphalt and is therefore ideal for reducing the issues of mixture pushing and checking during paving.
PG 64-28 is widely used in road construction and paving for new and pave maintenance projects, as well as in dense-graded and open-graded HMA. It is often used in low-elevation environments and can be used in spray treatments for bridge decks and pavement protection layers.
PG 70-22 is generally used in high-traffic areas and is the paving asphalt cement used in the manufacture of Hot Mix Asphalt (HMA). This grade is also suitable for pavement edge sealing and crack sealing.
The PG grades with the best thermal cracking resistance are PG 64-22, PG 76-22, PG 64-28, and PG 58-34. The grades with the best rutting resistance are PG 82-22, PG 76-28, PG 70-28, and PG 76-22. PG 64-22 is commonly used on toll roads (high volume), PG 70-22 is typical in toll booths (high volume and slow traffic), and PG 76-22 is typical in rest areas (high volume and standing traffic).