Bitumen Grades Explained: 60/70, 80/100, VG-30, VG-40, PG & PMB

Introduction

Bitumen is one of the most important materials used in road, highway, and pavement construction. It is due to its excellent binding and waterproofing properties. However, not all bitumen is the same. It is available in different grading systems, such as Penetration Grade (60/70, 80/100), Viscosity Grade (VG-30, VG-40), Performance Grade (PG), and Polymer Modified Bitumen (PMB), each designed for specific climate and traffic conditions. If you’re new to these two materials, it helps to first understand the difference between bitumen and asphalt. In this article, we’ll explain the major bitumen grades, how they differ, where they are used, and how to choose the right grade for your project.

What Are Bitumen Grades?

Bitumen grades are classifications used to distinguish bitumen based on standardized properties and performance characteristics. Depending on the grading system, bitumen may be classified according to its penetration, viscosity, or performance under different temperature conditions. Proper grading helps engineers and contractors select the most suitable bitumen for specific climates, traffic loads, and pavement requirements. 

Why Are There Different Bitumen Grading Systems?

Bitumen grades systems help engineers understand how different grades of bitumen perform under traffic loads and varying temperatures. They play a vital role in selecting the most suitable binder for roads, highways, airports, and other paving applications. Different grading systems have been developed to meet varying climate conditions, traffic demands, and engineering standards across different regions. The most commonly used grading systems include Penetration Grade, Viscosity Grade (VG), Performance Grade (PG), and Polymer Modified Bitumen (PMB), each of which is discussed below. 

Penetration Grade Bitumen

Penetration grade bitumen is a conventional paving binder widely used in road construction and asphalt pavement production. It is classified into different grades based on its penetration value, which indicates the hardness or softness of the bitumen. Common penetration grades include 30/40, 40/50, 60/70, 80/100, 100/120, and 160/220, with 60/70 and 80/100 being among the most widely used for pavement applications. 

Bitumen 60/70

Bitumen 60/70 has a penetration value ranging from 60 to 70. Due to its lower penetration range, it is harder and performs well in high-temperature conditions. It can withstand thermal and traffic loads while resisting rutting, making it suitable for highways, urban roads, and other heavy-duty paving applications. 

Bitumen 80/100

Bitumen 80/100 has a higher penetration range, making it softer, more flexible, and less prone to cracking. Its higher ductility allows it to accommodate temperature variations more effectively. Which makes it suitable for colder and moderate climates. Due to its flexible nature, Bitumen 80/100 is commonly used in bridge construction and other paving and construction applications. 

Viscosity Grade (VG)

Viscosity Grade Bitumen is a paving binder widely used in road construction and asphalt pavement production. It is classified into different grades based on its viscosity, which measures the bitumen’s resistance to flow at specified temperatures. Common viscosity grades include VG-10, VG-20, VG-30, and VG-40, with VG-30 and VG-40 being among the most widely used for road and highway construction. Each grade is designed for specific climate conditions and traffic loads, ensuring optimum pavement performance.

VG-30

VG-30 is one of the most widely used viscosity grades due to its balanced performance and durability. It is suitable for regions with average temperatures ranging from 30°C to 37°C, where pavements are exposed to moderate to heavy traffic loads. With an absolute viscosity of 1600–2400 poise at 60°C, VG-30 provides good resistance to deformation while maintaining adequate flexibility for long-term pavement performance. 

VG-40

VG-40 is a high-viscosity grade designed for demanding pavement conditions. Where greater stiffness and durability are required. It performs well in regions with high temperatures and under heavy traffic loads, helping asphalt pavements resist rutting and permanent deformation. With an absolute viscosity range of 3200–4800 at 60°C, VG-40 offers enhanced stability and long-lasting performance in challenging service conditions. 

Performance Grade Bitumen

Performance Grade (PG) Bitumen is widely used in flexible pavements. It is selected based on how it performs under actual road conditions. Unlike other grading systems, the Superpave Performance Grading (PG) system considers two important factors: pavement temperature and traffic conditions, including traffic volume. By selecting the appropriate PG grade, pavements become more resistant to common problems such as rutting, thermal cracking, bleeding, block cracking, shoving, depressions, and longitudinal or joint reflection cracking. Common Performance Grades include PG 58-28, PG 64-22, PG 64-28, PG 70-22, and PG 76-22, with the choice depending on pavement temperature and traffic conditions. 

PG 64-22

PG 64-22 is one of the most widely used Performance Grades for asphalt pavements. It is designed to perform in regions with warm summers and moderately cold winters, offering a balanced combination of durability and resistance to rutting and thermal cracking.

PG 70-22

PG 70-22 is designed for roads exposed to higher temperatures and heavier traffic loads. Its improved high-temperature performance helps asphalt pavements resist rutting and permanent deformation, making it suitable for highways and busy urban roads.

PG 76-22

PG 76-22 is a high-performance binder used in demanding pavement conditions. It provides excellent resistance to heavy traffic, high pavement temperatures, and repeated loading, making it ideal for expressways, airports, and industrial roads.

Polymer Modified Bitumen (PMB)

Polymer Modified Bitumen (PMB) is conventional bitumen that is modified by adding polymers to improve its overall performance. The polymers used are mainly elastomers and plastomers. They enhance the bitumen’s flexibility, elasticity, and durability. As a result, PMB is better able to withstand heavy traffic loads, resist rutting, cracking, and deformation. These improved properties make it a preferred choice for highways, expressways, bridges, airports, and other infrastructure projects that require long-lasting pavement performance. 

Bitumen Grade Comparison Table

How To Choose Right Bitumen Grade

Choosing the right bitumen grade is very important in any construction project. As the durability, performance, and overall quality of the pavement largely depend on the selected grade. Different bitumen grades are designed for different applications based on their specific characteristics, such as their performance under varying temperatures and traffic loads. Several factors should be considered before selecting a bitumen grade, including climate conditions, pavement temperature, traffic volume, and the specific requirements of the project. 

• Climate

Harder grades of bitumen are generally used in hot climates, as they provide better resistance to rutting and deformation. In contrast, softer grades are preferred in cold climates because they offer greater flexibility and help reduce thermal cracking.

• Traffic

Roads carrying heavy traffic loads require stronger and more durable binders, such as PMB or VG-40, to withstand repeated loading and resist permanent deformation. For light to moderate traffic, conventional grades such as 60/70 or VG-30 are often sufficient.

• National Standards and Specifications

The selected bitumen grade should comply with the national standards. It also depends on project specifications of the country (where the construction is taking place). Different regions may recommend or require different grading systems, such as Penetration Grade, VG, or PG bitumen.

• Project Requirements

Every construction project has unique requirements. Based on its design, expected service life, environmental conditions, and budget. Choosing a bitumen grade that meets these requirements. Helps ensure better pavement performance, durability, and long-term cost efficiency. Once you’ve selected a grade, the next step in mix design is to calculate the bitumen content needed for your project.

FAQs

1. What is the difference between 60/70 and 80/100 bitumen?

Bitumen 60/70 is harder and performs better in warm climates and under heavier traffic loads, while Bitumen 80/100 is softer and more flexible, making it suitable for moderate to cold climates where thermal cracking is a concern.

2. What is the difference between Penetration Grade and Viscosity Grade bitumen?

Penetration Grade (PG) classifies bitumen based on its penetration value, while Viscosity Grade (VG) classifies bitumen according to its viscosity, or resistance to flow, providing a better indication of its performance.

3. What is Performance Grade (PG) bitumen?

Performance Grade (PG) bitumen is classified using the Superpave Performance Grading system. It is selected based on pavement temperature and traffic conditions, allowing engineers to choose a binder that performs well under specific environmental and loading conditions.

4. What is Polymer Modified Bitumen (PMB)?

Polymer Modified Bitumen (PMB) is conventional bitumen enhanced with polymers to improve its strength, flexibility, and durability. It is commonly used in highways, bridges, airports, and other heavy-duty pavement applications.

5. Which bitumen grade is best for road construction?

There is no single best bitumen grade for every project. The appropriate grade depends on factors such as climate, pavement temperature, traffic volume, pavement type, and project specifications.

Conclusion

Selecting the right bitumen grade is essential for achieving durable, safe, and cost-effective pavements. Whether using Penetration Grade, Viscosity Grade, Performance Grade, or Polymer Modified Bitumen. Each grading system is designed to meet specific construction and environmental requirements. Understanding the characteristics and applications of different grades helps engineers, contractors, and project owners make informed decisions. Ultimately improving pavement performance and extending the service life of roads and other infrastructure.