What is Bitumen Performance Grade (PG)?

Bitumen Performance Grade, often referred to as PG, is a classification system for bitumen (asphalt) that is based on its performance characteristics at different temperatures. This grading system provides a more precise way of specifying bitumen for various climate and pavement conditions. PG bitumen is commonly used in road construction and asphalt mix designs.

Introduction to Bitumen Performance Grade:

Bitumen is traditionally classified based on penetration (hardness) and viscosity (consistency) at specific temperatures. However, the SHRP (Strategic Highway Research Program) engineers recognized that the performance of bitumen is highly dependent on temperature. As a result, they developed the PG grading system to account for the temperature sensitivity of bitumen.

PG Bitumen Grading System:

The PG bitumen grading system is based on the performance of bitumen at low, medium, and high temperatures. It is represented by a combination of two numbers, such as PG 58-28. Here’s what these numbers mean:

• PG 58: This number represents the average temperature (in degrees Celsius) of the seven successive days of the highest pavement temperature in the summer season. In this example, it’s 58°C.
• -28: This negative number indicates the lowest temperature (in degrees Celsius) of the pavement in the seven successive days of the winter season. In this example, it’s -28°C.

So, PG 58-28 bitumen is suitable for use in an area where the maximum pavement temperature in summer is 58°C, and the lowest pavement temperature in winter is -28°C. It implies that this bitumen may not perform well in temperatures higher than 58°C or lower than -28°C.

Modified vs. Unmodified PG Bitumen:

PG grades are categorized into two main types: Modified and Unmodified bitumen. The distinction between them is determined by the sum of the high-temperature and low-temperature values. If this sum is greater than 92°C, the bitumen is considered a polymer-modified bitumen. For example, PG 76-22 is a polymer-modified binder because the sum is 98. In contrast, PG 64-10 is an unmodified binder because the sum of 64 and 10 equals 74. Generally, grades in the darker part of the table are considered modified bitumen.

PG Bitumen Tests:

PG bitumen undergoes various tests to determine its suitability for specific applications and temperature ranges. These tests include but are not limited to:

• Viscosity Determination of Bitumen Using Rotational Viscometer (RV)
• Determining the Rheological Properties of Bitumen Using a Dynamic Shear Rheometer (DSR)
• Determining the Fracture Properties of Bitumen in Direct Tension (DT)
• Determining the Flexural Creep Stiffness of Bitumen Using the Bending Beam Rheometer (BBR)
• Rolling Thin-Film Oven Test (RTFOT) to assess the effect of heat and air on bitumen
• Accelerated Aging of Bitumen Using a Pressurized Aging Vessel (PAV)
• Elastic Recovery Test
• Determining the Separation Tendency of Polymer from Polymer-Modified Bitumen

These tests help evaluate bitumen’s resistance to rutting, fatigue, thermal cracking, and other performance-related factors under specific temperature conditions.

Note: The PG bitumen grading system is widely used in the United States and other countries for specifying bitumen in road construction projects. The PG system ensures that the selected bitumen is suitable for the local climate and pavement conditions.

BituPlus Supplies the Following Bitumen PG Grades:

BituPlus offers a wide range of Bitumen Performance Grade (PG) grades to cater to diverse construction and infrastructure needs. Our PG bitumen grades are carefully selected to ensure optimal performance across various temperature ranges and environmental conditions.

Our PG bitumen product line includes grades designed to meet the specific requirements of different regions and applications. Whether you need bitumen suitable for high-temperature environments or extreme cold climates, BituPlus has you covered.

Explore our comprehensive selection of PG bitumen grades to find the perfect solution for your project. We are committed to providing high-quality bitumen that meets industry standards and delivers superior performance in a wide range of construction applications. Contact us for more information on our PG bitumen offerings and how they can benefit your projects.

Specification of Performance Grade(PG) Bitumen

	PG 46-34	PG 46-28	PG 52-28	PG 58-28	PG 58-22	PG 64-22	AASHTO Method
Original Binder
Flash Point, COC,°C	230						T 48
Flash Point, P-M, °C	NS			≥ 204			ASTM D93
Rotational Viscosity @ 135°C, Pa·s	3.00						T 316
Dynamic Shear @ Grade Temperature,°C	46	46	52	58	58	64	T 315
G*/sin @ 10 rad/sec, kPa	≥ 1.00
RTFOT Residue
Mass Loss, %	≤ 1.00						T 240
Dynamic Shear @ Grade Temperature,°C	46	46	52	58	58	64	T 315
G*/sin @ 10 rad/sec, kPa	2.20
PAV Residue (Aging Temperature, °C)	90			100			R 28
Dynamic Shear @ Grade Temperature,°C	10	13	16	19	22	25	T 315
G*/sin @ 10 rad/sec, kPa	5000
Creep Stiffness	-24	-18	-18	-18	-12	-12
S, Mpa	≤ 300						T 313
m-value	≥ 0.30						T 313

Applications of PG Bitumen

Performance Grade (PG) bitumen is widely used in flexible pavement applications due to its ability to enhance pavement durability and longevity. It helps mitigate various types of pavement distresses, ensuring smoother and safer roads. Here are some key applications of PG bitumen:

1. Rutting Prevention: PG bitumen grades like PG 70-22, PG 70-28, PG 76-28, and PG 82-22 are specifically chosen to resist rutting, which is a common pavement issue caused by repeated heavy loads.
2. Thermal Cracking Prevention: PG grades such as PG 58-34, PG 64-22, PG 64-28, and PG 76-22 are selected to prevent thermal cracking, which occurs due to temperature fluctuations.
3. Fatigue Resistance: PG bitumen helps reduce fatigue or alligator cracking, which results from the repeated application of traffic loads. It ensures longer pavement life and lower maintenance costs.
4. Other Pavement Distresses: PG bitumen also addresses various other pavement distresses, including bleeding, block cracking, corrugation and shoving, depression, joint reflection, and longitudinal cracking.

It’s important to note that the PG grading system considers fundamental properties like stresses and strains of bitumen at different temperature conditions throughout the pavement’s expected lifespan. This approach provides a more comprehensive assessment of bitumen performance compared to the viscosity grading system, which only measures consistency at a specific temperature (60°C).

By selecting the appropriate PG bitumen grades for specific applications, road engineers can design pavements that are better suited to withstand the challenges posed by traffic loads, temperature variations, and other environmental factors, resulting in safer and longer-lasting roads. Contact us to learn more about our PG bitumen offerings and how they can benefit your pavement projects.