Bitumen Types and Grades

Types and grades of bitumen are classified based on several factors, such as penetration, viscosity, and composition.

 Additionally, we can classify bitumen differently based on their origins:

• Refinery Bitumen: Known as bitumen for short, it’s derived from crude oil.
• Natural Bitumen: With a chemical composition similar to refinery bitumen, this form is found in nature either in pitch lakes or as lumps extracted from mines.

Bitumen classification systems have expanded over time to reach the best performance of bitumen in different projects.

Read this article to discover key information about bitumen types, grades, and their differences.

Penetration Grade Bitumen

Penetration bitumen is the most commonly used type of bitumen in road construction. It is categorized into several grades based on a penetration test that measures bitumen hardness at 25°C.

60/70 and 80/100 are two widely used penetration grades. For a balance of flexibility and durability,  bitumen 60/70 is a popular choice with a penetration range of 60 to 70.

With a higher penetration range, the bitumen 80/100 is softer and more resistant to cracking, making it suitable for colder climates.

Beyond road construction, penetration bitumen also finds applications in waterproofing and other construction-related activities.

Learn about the different types of bitumen used in road layers, from subgrade to surface course. (+Infographic)

In the table below, you can see the specifications for this grade:

Sometimes the same grade of bitumen penetration has different behavior at high temperatures. It is the main weakness of this grading method. This led to the introduction of the viscosity grading system.

Viscosity Grade Bitumen (VG Bitumen)

The United States introduced the viscosity grading system in the late 20th century. Viscosity bitumen is graded based on viscosity at 60°C and 135°C.

In this type of bitumen, penetration at 25 °C is also measured. These properties help us to understand how bitumen responds to temperature fluctuations.

Viscosity at 60 °C shows bitumen’s resistance to flow in hot climate conditions. On the other hand viscosity at 135 °C determines the behavior of bitumen while its temperature is very high for preparing hot mix asphalt. Penetration at 25 °C measures consistency at room temperature.

Unlike the penetration test, which is an empirical method, the viscosity test of bitumen provides a more fundamental approach to analyzing bitumen’s behavior in a specific range of temperatures. 

The highest consumption of VG bitumen is in India. Viscosity bitumen has four different grades that are VG10, VG20, VG30, and VG40. You can see their specification below:

Penetration and viscosity grade bitumen have some limitations in accurately predicting how bitumen will perform in real-world conditions. That’s where PG bitumen shines, providing a more reliable and scientific estimation.

Take a closer look at viscosity bitumen, for further details such as its meaning, advantages, applications, etc.

Performance Grade Bitumen (PG Bitumen)

PG bitumen is classified based on its ability to handle different temperatures and maintain desired properties.

Compared to traditional grading methods such as penetration and viscosity, PG bitumen focuses on the overall performance of the bitumen rather than its physical properties.

Performance grade bitumen is named with two numbers that show its performance ranges. For example, PG 76-16 indicates it’s resistant to temperatures as high as 76°C and as low as -16°C. 

PG bitumen is evaluated using various rheological and aging tests. The Dynamic Shear Rheometer (DSR) measures its resistance to deformation, while the Pressurized Aging Vessel (PAV) simulates long-term aging. Additionally, Direct Tension (DT) tests determine its flexibility and resistance to cracking under repeated load applications.

These tests provide detailed information about long-term performance under varying stress and temperature conditions.

The table below lists the specifications for different grades of PG bitumen:

AH Bitumen

AH bitumen is a popular bitumen type in the China market. They are graded based on penetration value at 25°C, like penetration grades. However, they have some differences in their tests and specifications.

In contrast to the penetration grading system, viscosity at 60 °C is also measured in AH bitumen. The temperature of 60 °C corresponds to the highest pavement temperature during hot summer when rutting problems occur. Therefore, knowing the viscosity of bitumen at this temperature helps to better control one of the main problems of pavement distress.

Another difference is the testing of AH bitumen’s ductility at both 10 and 15 °C. 

At 15 °C, AH bitumen has a ductility of over 100 cm, while penetration bitumen reaches the same ductility at 25°C. This indicates that AH bitumen can maintain its flexibility well even in cold weather.

The most widely used grade of AH bitumen is AH 70, also referred to as bitumen 60/80, due to its ideal penetration range of 60 to 80 dmm. 

The specifications for AH bitumen grades are shown in the table below:

Asphalt Cement Bitumen (AC Bitumen)

AC grade, or asphalt cement bitumen, is a viscosity-based grade of bitumen, defined by the American Association of State Highway Officials (AASHTO). 

AC bitumen is categorized based on its average dynamic viscosity at 60 °C, divided by 100. For example, AC10 bitumen has a viscosity range of 800-1200 Poise.

They are demanded in some markets like Sudan, Ghana, Cameroon, Djibouti, South Africa, Guinea, and Zimbabwe. Its main specifications are: penetration at 25°C, viscosity at two temperatures of 60°C and 135°C.

See the detailed specification of AC bitumen in the below table:

Visit AC grade bitumen, if you need more information about its grades and price.

Oxidized Bitumen

Oxidized or blown bitumen is a bitumen type produced by blowing air into the pure bitumen.This process is done at high temperatures to modify its physical properties for specific uses.

The process of blowing air causes oxidation and polymerization, resulting in larger molecular weight molecules that form a harder and less temperature-sensitive product.

As the asphaltene percentage increases, oxidized bitumen has a lower penetration value and a greater softening point than pure bitumen.

The grading method for blown bitumen is based on penetration and softening points. Their grades and specifications are as below:

Read a detailed review on Oxidized Bitumen (Blown Bitumen), including its grade, packing, uses, etc.

Cutback Bitumen

Cutback is a type of liquid bitumen that is produced by blending penetration grade bitumen with a petroleum solvent such as gasoline, kerosene, and diesel. The percentage of solvent is varied from 20 to 45%.The main uses of them are in producing cold mix asphalt and sealing applications. 

Curing time is defined as the speed of solvent evaporation and remaining bitumen. Cutback bitumen has different curing times, as follows:

• Slow Curing (SC): Produced using heavy petroleum solvents, such as diesel or mazut
• Medium Curing (MC): Produced using semi-heavy petroleum solvents, such as kerosene
• Rapid Curing (RC): Produced using light petroleum solvents, such as gasoline

Cutback bitumen is classified based on curing time and viscosity. You can compare their specifications in the below tables:

What is Cutback Bitumen? Click to read everything you need to know about cutback bitumen.

All petroleum solvents in cutback bitumen will eventually evaporate, which is serious damage to the environment. To avoid this problem, emulsion bitumen came into the industry.

Emulsion Bitumen

Bitumen emulsions are a new way for liquifying bitumen by dispersing it in water. In this bitumen type, very fine particles of bitumen are suspended in water, which are stable by using an emulsifier.

The amount of bitumen in the emulsion varies from 55 to 65%. Two key factors determine the grades of emulsion bitumen:

1- Particles’ electrostatic charge of the emulsifier:

• Cationic: Bitumen particles have a positive electrical charge.
• Anionic : Bitumen particles have a negative electrical charge.

Cationic bitumen emulsion has more applications than anionic. This is due to its superior adhesion to stone materials such as silica and quartz compounds, which have a negative electric charge. This makes them a better choice in road construction, building, and sealing projects.

2- Breaking or setting time: the time that is required for water to evaporate

• Slow setting (SS)
• Medium setting (MS)
• Rapid setting (RS) 

Setting time can take from as little as 10 minutes to several hours depending on ambient temperature, humidity, aggregate water absorption, wind speed, etc.

Bitumen emulsion is more eco-friendly than cutback bitumen due to the use of water instead of petroleum solvent.

Generally, liquid bitumen doesn’t need heating because of their low viscosity. That’s a significant advantage, since their operation is easier and requires less energy.

Are you interested in reading more about the difference between cutback and emulsion? (11 Differences + Video)

Gilsonite

Gilsonite, or natural bitumen, is a solid hydrocarbon with very high purity, extracted from mines. It is rich in asphaltenes and nitrogen compounds, containing little sulfur or ash. Gilsonite is shiny and black. It breaks easily. 

Its specific compatibility allows it to be used for hardening softer petroleum compounds.

Gilsonite can be used as an additive to hot mix asphalt, which improves asphalt performance such as stiffness, flexibility, and resistance to moisture damage.

Natural bitumen is usually used as a powder, which comes in different ash contents, particle sizes, and solubility levels in organic solvents.

Based on the amount of ash content, there are four different types of micronized gilsonite powder:

• 5% ash content
• 10% ash content
• 15% ash content 
• 20% ash content

Gilsonite asphalt is also found in different mesh sizes, which show the different particle sizes of the powder. Most gilsonite is available in mesh sizes ranging from 30 to 200 mesh (595 to 74 microns). The particle size gets bigger as the mesh number goes down, and the opposite is also true.

One of gilsonite’s key properties is its solubility level in organic solvents, measured in carbon disulfide (CS₂). The higher solubility makes it valuable for various industrial applications, including in the production of paints, coatings, and asphalt modifiers.

Check out the specifications of gilsonite used in various applications below:

Specifications of Gilsonite in Different Applications
Specifications	Test Method	Drilling	Asphalt & Road	Isolation	Paint & Ink	Foundry
Ash Content, WT%	ASTM D3174	7-13	10-15	10-20	7-10	10
Mesh Size	ASTM D546	200	100-200	100	200	100-200
Moisture  Contentment, WT%	ASTM D3173	1-3	1-3	1-3	1-3	1-3
Volatile Matter, WT%	ASTM D3175	65-85	65-85	65-85	65-85	65-85
Solubility in CS2,WT%	ASTM D4	75-85	70-80	70-80	80-90	75-85
Specific Gravity, at 25 °C	ASTM D3289	1.05	1.05	1.05	1.05	1.05
Color	–	Black	Black	Black	Black	Black
Softening Point	ASTM D36	180-220	180-220	180-220	180-220	180-220

If you would like to know more about Gilsonite, click here.

Infinity Galaxy team is ready to guide you through your bitumen needs. Leave a comment or reach out via WhatsApp for expert guidance or to place an order.