Viscosity Grade VG Bitumen (VG 10,VG 30,VG 40)

Published on 11 Sep 2023Updated on 7 Mar at 6:19 am

Share this article

Table of Contents

What is Viscosity Grade Bitumen (VG)?

Viscosity Grade VG Bitumen in the context of bitumen refers to the thickness or resistance to the flow of bituminous materials, such as asphalt or tar. Bitumen is a highly viscous and sticky black or brown substance that is derived from crude oil during the refining process. Its viscosity is a key property that determines its suitability for various applications, especially in the construction and paving industries.

Bitumen viscosity is influenced by several factors, including temperature, shear rate, and the type of bitumen.

Here are some key points to understand about bitumen viscosity:

Temperature Dependence: Bitumen’s viscosity is highly temperature-dependent. As temperature increases, bitumen becomes less viscous and flows more easily. Conversely, as temperature decreases, bitumen becomes more viscous and can become solid or very thick.
Rheology: Bitumen’s flow behavior, or rheology, is described as non-Newtonian, meaning its viscosity changes with shear rate. At low shear rates, such as when it’s not being actively mixed or agitated, bitumen can be very thick and exhibit high viscosity. When subjected to high shear rates, as in the mixing and application processes, it becomes less viscous and easier to work with.
Grading: Bitumen is often classified into different grades based on its viscosity at specific temperatures. The most commonly used grading system for bitumen is the penetration grading system and the viscosity grading system. For example, the penetration grade 60/70 bitumen has specific viscosity and penetration values at certain temperatures.
Application: The choice of bitumen viscosity is crucial in various construction and paving applications. Lower viscosity bitumen is used in applications where it needs to flow easily, such as in asphalt paving, while higher viscosity bitumen is used in roofing materials and waterproofing applications.
Modifiers: Bitumen can be modified with additives and polymers to alter its viscosity and other properties. This is done to improve its performance in specific applications, such as increasing its resistance to cracking or improving its adhesion properties.

General Description of VG Bitumen

Viscosity Grade Bitumen (Asphalt) is a standard grade Bitumen usually used as a Paving Grade Bitumen suitable for road construction and for the production of asphalt pavements with superior properties. This grade of Bitumen is mainly used in the manufacture of hot mix asphalt for bases and wearing courses and possesses characteristics and qualities unique and quite different from other agents. They achieve very flexible and tenacious connections with other materials due mainly to the viscoelastic response of bitumen, whose behavior depends on how fast charges are applied.

Viscosity Grade bitumens are specified by the methods described in ASTM Standard D3381-09 and AASHTO M226-80 (2008). Viscosity Graded specifications cover bitumen (asphalt) graded by Viscosity at 60 C (140 °F).

History of Viscosity Grade Bitumen

Bitumen has been used by civilizations for thousands of years, primarily as a waterproofing and adhesive material. Ancient civilizations like the Sumerians and Egyptians used bitumen for various applications, including building construction and shipbuilding.

As industrialization advanced, the need for standardized specifications for bitumen became evident, especially in the construction and road paving industries. Standardization was essential to ensure that bitumen met specific performance criteria.

Application of Viscosity Grade Bitumen

Grade	Viscosity Range at 60°C (Absolute Viscosity)	Typical Applications
VG-10 Bitumen	800-1200	Recommended for road construction in cold regions Ideal for spraying Used in production of bitumen emulsion
VG-20 Bitumen	1600-2400	Used in cold regions for road construction
VG-30 Bitumen	2400-3600	Maximizes asphalt performance in hot regions A more reliable choice than bitumen pen 60/70
VG-40 Bitumen	3200-4000	Works in areas with high traffic loadsWell suited for road construction in hot weather

Advantages of VG Bitumen

1–Unlike penetration depth, viscosity is a fundamental engineering parameter.

2-Test temperatures correlate well with:

25°C (77°F) – average pavement temp.
60°C (140°F) – high pavement temp.
135°C (275°F) – HMA mixing temp.

3-Temperature susceptibility (the change in asphalt binder rheology with temperature) can be somewhat determined because viscosity is measured at three different temperatures (penetration only is measured at 25°C (77°F))

4-Testing equipment and standards are widely available.

Disadvantages of VG Bitumen

1-The principal grading (done at 25°C (77°F)) may not accurately reflect low-temperature asphalt binder rheology.

2-When using the AC grading system, thin film oven test residue viscosities can vary greatly with the same AC grade. Therefore, although asphalt binders are of the same AC grade they may behave differently after construction.

3-The testing is more expensive and takes longer than the penetration test.

important tips about VG Bitumen

Performance at high temperatures by adopting a viscosity-graded of bitumen specification (based on viscosity at 60 °C), in place of the current penetration-graded specification (based on penetration at 25 °C)
Issues relating to compaction, which the tender asphalt mixtures create as push and shove under the roller wheels, have also addressed by having a requirement of minimum viscosity at 135°C, it will be helpful in minimizing the tender mix problems in the field.
Adoption of viscosity grade paving bitumen specifications will also reduce the number of total tests to 7 Without compromising the quality of bitumen and also no new tests are required in implementing this specification.

The viscosity grade of bitumen is categorized according to Viscosity (degree of fluidity) grading. The higher the grade, the stiffer the Bitumen. In the Viscosity Grade, Viscosity tests are conducted at 60°C and 135°C, which represents the temperature of the road surface during summer and mixing temperature respectively. The penetration at 25°C, which is the annual average pavement temperature

Bitumen is graded based on absolute viscosity at 60 ºC or kinematic viscosity at 135 ºC. The SI physical unit of dynamic viscosity is Poise and kinematic viscosity is expressed in CentiStokes. Pure bitumen has been graded based on AASHTO-M226 and ASTM-D3381 standards.

Production Process of Viscosity Grade Bitumen

Crude Oil Extraction: The first step involves extracting crude oil from oil wells. This crude oil consists of various types of hydrocarbons, including the heavy fractions that form bitumen.
Distillation: The extracted crude oil undergoes atmospheric distillation in a refinery. This process heats the oil, causing different fractions to evaporate and condense at different temperatures. The lighter fractions, such as gasoline and diesel, are removed at lower temperatures, while the heavy bitumen fraction is left behind.
Vacuum Distillation: The remaining heavy oil from the atmospheric distillation unit is then subjected to a second distillation process under vacuum conditions. This step enables the removal of the remaining lighter fractions without causing thermal cracking of the bitumen.
Air Blowing: To achieve desired properties, the vacuum residue is then subjected to an air-blowing process, where hot air is passed through the residue. This procedure induces certain reactions that enhance the bitumen’s physical and performance properties, allowing it to withstand various weather and load conditions.
Viscosity Grading: The final stage of the process is the grading of the bitumen based on its viscosity. The bitumen is heated to a standard temperature of 60°C, and its viscosity is measured in centistokes (cSt). Depending on the viscosity, the bitumen is categorized into different grades, such as VG10, VG20, VG30, or VG40.

Definition of HS code, chemical Number, and CAS Number of VG Bitumen

HS Code: The Harmonized System (HS) Code for bitumen, including VG Bitumen, is 27132000.
This HS code refers to “Bituminous or oil shale and tar sands.”
Chemical Formula: Bitumen doesn’t have a precise chemical formula as it is a complex mixture of hydrocarbons. The composition of bitumen can vary widely, containing thousands of different molecules, mainly composed of carbon and hydrogen, and often also containing oxygen, sulfur, and nitrogen.
CAS Number: Similar to the chemical formula, there isn’t a specific Chemical Abstracts Service (CAS) number for VG Bitumen as it is a mixture of various compounds. However, the CAS number generally used for bitumen is 8052-42-4, though it’s crucial to remember that this covers a broad range of materials, including the different viscosity grades of bitumen.

Grades of Viscosity Grade Bitumen

General Description of Viscosity Grade 10

Bitumen Viscosity Grade 10, which has a permeability rating of 80/100, is the method of choice for coating surfaces and roads. This particular variety of bitumen is required for the manufacturing of emulsion bitumen and other modified bitumen products. This grade of bitumen can be a good substitute for penetrating bitumen 80/100.

Advantage of VG Bitumen 10

It is appropriate for temperatures below 30 °C.
It has an 800 absolute viscosity.
When compared to VG30 and VG40, it has a better penetration value.

Description of Bitumen Viscosity Grade 20

Bitumen Viscosity Grade 20 (often abbreviated as VG-20) is a standardized classification of bitumen, which is a black, viscous, and semi-solid form of petroleum used primarily in road construction and waterproofing applications. Viscosity grading is a common method used to categorize bitumen based on its flow characteristics at a specific temperature, typically measured in centistokes (cSt) or Saybolt Furol seconds (SFS).

Advantage of VG Bitumen 20

High-altitude, cold climate areas employ VG-20 bitumen, a grade of viscosity bitumen.
When building roads in areas where the average temperature is between 30 and 37 °C, this grade of bitumen is appropriate.

Viscosity Grade Bitumen 30 Description

Bitumen Viscosity Grade 30 is used to build super-heavy bituminous pavements. These types of sidewalks must withstand high and significant traffic loads, so this type of grade is used more often. Road construction, construction, insulation, and liquid bitumen are the most common industries that use this type of bitumen.
VG30 bitumen is very suitable for temperate climates and can be used instead of bitumen 60/70.

Advantage of VG 30 Bitumen

It can withstand temperatures higher than 30 °C.
Bitumen with a greater viscosity is more suited for clayed soil.
In wet conditions, VG30 is better appropriate for road building.

VG Bitumen 40 Description

In highly stressed areas such as intersections, highways near tolls, and truck parking lots, VG 40 bitumen with a permeability of 40/50 is used instead of the old bitumen. Due to its high viscosity, this type of mixed hard bitumen is suitable for surfaces that are supposed to bear high tensile strength loads and heavy traffic loads. This type of bitumen is used at higher temperatures and on surfaces that require more resistance and it can be a suitable alternative to penetration bitumen 40/50 and penetration bitumen 30/40.

Advantage of VG 40 Bitumen

It can withstand temperatures exceeding 40 °C.
It has a 3200 absolute viscosity.
It is the ideal kind of bitumen when there will be a lot of traffic.

Standards of VG Bitumen

Viscosity Grade bitumen is determined by IS 73, ASTM and AASHTO. According to the IS, grading of Bitumen is changed from penetration grade to viscosity grade in 2006.

There are two Methods of Grading:

1- Standard Viscosity Grade Bitumen (AC-Grades), in which the Viscosity of the standard bitumen (asphalt) is measured at 60 ºC (140 ºF).

2- RTFOT Viscosity Grade Bitumen (AR-Grades), in which the Viscosity of bitumen (asphalt) is measured at 60 °C (140 °F) after the roll-on thin film oven test.

Viscosity grade bitumens have a thermoplastic property which causes the material to soften at high temperatures and to harden at lower temperatures. This unique temperature/ viscosity relationship is important when determining the performance parameters such as the adhesion, rheology, durability, and application temperatures of bitumen. In the Viscosity Graded Bitumen specifications, special emphasis is placed on the Bitumen ductility.

Standard Viscosity Grade Bitumen Blinders, Including:

VG Bitumen AC-2.5
VG Bitumen AC-5
VG Bitumen AC-10
VG Bitumen AC-20
VG Bitumen AC-30
VG Bitumen AC-40

Maintaining Surfaces of VG Bitumen

Regular inspections for wear, cracks, potholes, and fading road markings.
Promptly repair minor damage to prevent expansion.
Resurface when necessary by replacing the top layer.
Apply sealcoat for protection against UV, rain, and chemicals.
Ensure proper drainage to prevent water pooling.
Control traffic to avoid excessive weight on the surface.
Consider professional assistance for major maintenance tasks, prioritizing longevity and safety.

Installation of VG Bitumen

The installation of Viscosity Grade Bitumen (VG Bitumen), particularly for road construction, involves several stages. The process is generally as follows:

Preparation: The first step is preparing the surface where the bitumen will be laid. This might involve removing any old pavement and leveling or compacting the surface to ensure it is smooth and stable.
Heating: The VG Bitumen needs to be heated before it can be used. This is typically done in a specially designed heater or boiler that can bring the bitumen up to the necessary temperature without overheating it.
Mixing: The heated bitumen is then mixed with aggregate materials to create the asphalt. This mixture is also heated to ensure it remains workable during the installation process.
Laying the Asphalt: The hot asphalt mixture is then spread onto the prepared surface using an asphalt paver. The paver evenly distributes the asphalt, and then heavy rollers compact it to create a smooth, hard surface.
Cooling: Once the asphalt is properly compacted, it needs to cool down before it can be used. During this time, the bitumen hardens and binds the aggregate together, forming a strong, durable road surface.
Sealing: In some cases, the surface may be sealed with a thin layer of bitumen or a bitumen-based sealant. This provides additional weather resistance and can help extend the lifespan of the pavement.

How to Select the Proper Viscosity Grade Bitumen?

To select the proper viscosity grade bitumen based on the IS73 standard, the mean temperature of the field should be in one of the divisions of the following table:

Grade	Suitable for 7 days Average Maximum Air Temperature ° C
VG 10	< 30
VG 20	30 – 38
VG 30	38 – 45
VG 40	> 45

Specification of Viscosity Bitumen (ASTM D3381-09)

Property	Units	AC-10	AC-20	AC-30	AC-40	Test Methods
Viscosity, 140°F (60°C)	P	1000±200	2000±400	3000±600	4000±800	ASTM D-2171
Viscosity, 275°F (135°C), Min	cSt	150	210	250	300	ASTM D-2171
Penetration, 77°F (25°C), 100g, 5sec, Min	0.1MM	70	40	30	20	ASTM D-5
Flash point, Cleveland open cup, Min	°C	219	232	232	232	ASTM D-92
Solubility in trichloroethylene, Min	%Wt	99	99	99	99	ASTM D-2042
Viscosity, 140°F (60°C), Max	P	5,000	10,000	15,000	20,000	ASTM D-2171
Ductility, 77°F (25°C), 5cm/min, Min	CM	50	20	15	10	ASTM D-113

Technical Data Sheet of VG Bitumen (IS 73:2013)

Property	Units	VG-10	VG-20	VG-30	VG-40	Test Methods
Penetration at 25°C, 100g, 5sec, Min	0.1MM	80	60	45	35	IS 1203
Absolute viscosity at 60°C	P	800-1200	1600-2400	2400-3600	3200-4800	IS 1206 (Part 2)
Kinematic viscosity at 135°C, Min	cSt	250	300	350	400	IS 1206 (Part 3)
Flash point (Cleveland open cup), Min	°C	220	220	220	220	IS 1448 [P : 69]
Solubility in trichloroethylene, Min	%Wt	99	99	99	99	IS 1216
Softening point (R&B), Min	°C	40	45	47	50	IS 1205
Viscosity ratio at 60°C, Max	-	4	4	4	4	IS 1206 (Part 2)
Ductility at 25°C, Min	CM	75	50	40	25	IS 1208