Bitumen - Viscosity Grade

Bitumen Viscosity Grade - VG 10, VG 20, VG 30 & VG 40

The most popular type of bitumen in India, known as Viscosity Grade Bitumen in four different grades (VG10, VG20, VG30, and VG40), has been superseded by bitumen penetration grade in accordance with Indian Standard (IS:73).

Because of its benefits and characteristics, this type of bitumen is more dependable than others. You will learn more about the uses, characteristics, and specifications of each grade in the sections that follow, and you may locate the besat VG bitumen for your needs.

What distinguishes Viscosity Grade Bitumen from Penetration Grade Bitumen?
The difference between viscosity grade bitumen and penetration grade bitumen is that the viscosity grade classification is based on the Viscosity value in both 60 °C and 135 °C, whereas the penetration grade classification is based on the Penetration value in 25 °C, demonstrating that it is suitable for both low and high temperature so that the bitumen behavior in various thermal conditions can be predicted well.

Classification of Bitumen with Various Viscosities
When bitumen is subjected to a viscosity test, it is categorized into a number of grades, including VG10 Bitumen, VG20 Bitumen, VG30 Bitumen, and VG40 Bitumen. In the viscosity grading method, the harder the bitumen, the higher the number. See the table at the end of the article for further information about VG's specification and a comparison of the qualities of the grades.

Grades of viscosity Standards
IS 73, ASTM, and AASHTO all determine the viscosity grade of bitumen. The IS states that in 2006, the classification of bitumen changed from penetration grade to viscosity grade.

Viscosity Grade Bitumen Application
According to the two crucial aspects of climate and traffic conditions, each of these viscosity grades of bitumen typically has a particular application.
The existence of two crucial characteristics of this substance, namely water impermeability and strong adhesion, accounts for the significant application of VG bitumen. There are already more than 250 uses for VG bitumen, making it seem difficult to use another substance in their stead.

Benefits of Bitumen with Higher Viscosity
Since VG bitumen has undergone more thorough testing in two phases than penetration bitumen, it is now preferred. The viscosity of bitumen is measured at 60 °C and 135 °C after the penetration of bitumen, which is initially measured at 25 °C, which is the average temperature, is determined. These tests demonstrate that:

VG bitumen can withstand a wide range of temperatures, including 135°C for construction and 25°C for fatigue cracking. Temperature susceptibility can also be calculated.
A smaller number of tests saves time and money; according to IS, penetration has 14 tests whereas it just has 7.
Longer durability: The VG Bitumen pavement will perform better since the Viscosity value at 135°C provides a sufficient understanding of the mixing and compaction temperature, which increases the pavement life.
In contrast to penetration grade, any two samples of the same VG bitumen would exhibit comparable rutting performance during the hot summer.
VG bitumen is suited for locations with heavy traffic loads because it has a minimum defined kinematic viscosity value at 135 °C that helps to reduce the possibility of tender mixtures during construction.

Bitumen VG 10: Brief Description
The softest grade of viscosity bitumen is VG10. This kind of bitumen is frequently used for surface coating and spraying applications.
Instead of the conventional 80/100 penetration grade, VG 10 bitumen indicates that your bitumen is also acceptable for paving roads in a very cold climate. The range of air temperatures for VG10 bitumen is -10 C to 25 C.
The use of VG10 cannot give the desired rutting resistance due to the high temperatures in hot climate zones.
This kind of bitumen is also employed in the production of modified bitumen products, particularly in India.
As a bitumen with a higher viscosity grade, VG10 performs better in cold climates.

What are the Benefits of Using Bitumen with a Viscosity of Grade 10?

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

Bitumen VG 20: Brief Description
A grade of viscosity bitumen called VG-20 is utilized in areas with cold climates and high altitudes. When building roads in areas where the average temperature is between 30 and 37 °C, this grade of bitumen is appropriate Q
Vg20 is used in hot mix Bitumen for road construction in North India. The bitumen viscosity grade VG-20 has a specified penetration value of 60 mm at 25 °C. At 60 °C, VG-20 bitumen has an absolute viscosity of 1600 to 2400 poise.

Bitumen VG 30: Brief Description
In order to build extra-heavy bitumen pavements that can support heavy traffic loads, this bitumen is predominantly used. The most common form of bitumen used in the construction of roads, buildings, and insulation is bitumen VG30, which is also used to make cutback bitumen. Knowing that this VG30 bitumen can be utilized in place of VG60/VG70 penetration bitumen grade is preferable.
We use VG30 in hotter environments because of its excellent thermal susceptibility. In addition, VG-30 bitumen can be used in hot, rainy weather instead of bitumen penetration grades. The likelihood of bitumen being impacted by water decreases with bitumen viscosity.

What are the VG-30's Minimum and Maximum Viscosities?
The range of viscosity [(100 +- 20) * 30] in terms of Poise is what is meant by the number 30 in the viscosity bitumen classification for VG 30 bitumen. Calculating the VG30's minimum and maximum is achievable. Calculating the maximum viscosity at 120°C also uses the formula 80 * 30 to determine the minimum viscosity at 60°C, which is 2400 poise.
The Distinction from VG10 to VG30:
The viscosity of VG10 and VG-30 bitumen differs from one another. Because bitumen VG30 is more viscous than bitumen VG10, it performs better when used to build roads in hot climates.

What are the benefits of using bitumen with a viscosity grade of 30?

It can withstand temperatures higher than 30 °C.
Higher viscosity bitumen is more suited for a clayed soil.
In wet conditions, VG30 is more suited for road building.
The density of VG 30 bitumen, according to ASTM, is 1.01.

Bitumen VG 40: Description

VG40 bitumen is utilized in places like junctions, close to toll booths, and truck parking lots where there is high pressure from significant traffic loads.

This bitumen's high viscosity makes it more suitable for enhancing resistance to pushing and other issues brought up by hotter temperatures and strong traffic loads. Industries have traditionally used VG-40 in place of penetration grade bitumen 40/50.

The Distinction from VG30 to VG40:

The VG30 and VG40 bitumen differ in that the VG30 bitumen is more suited for usage in moderate climates while the VG40 bitumen is better suited for use in hot climates.

What are the benefits of using bitumen with a viscosity grade of 40?
It is appropriate for temperatures higher than 40 °C.
It has a 3200 absolute viscosity.
In situations where there will be a lot of traffic, this type of bitumen is preferred.
The kinematic and absolute VG-40 bitumen viscosities are 400 and 3200, respectively.

The Table shows several uses and characteristics of VG Bitumen.

Bitumen VG 10: Specification

Bitumen VG 20: Specification

Bitumen VG 30: Specification

Bitumen VG 40: Specification

How to Choose the Right Bitumen Grade for Viscosity?
The field's mean temperature needs to fall within one of the divisions of the following table in order to choose the right viscosity grade bitumen in accordance with the IS73 standard:

3 Different Bitumen Viscosity Tests: Tools and Techniques

The bitumen viscosity is measured by the viscosity test. This characteristic demonstrates how fluid bitumen is. The harder it is for bitumen to flow, the higher its viscosity. It acts more like semi-solid stuff as a result. Viscometers are used to measure the viscosity of bitumen.

The following is a list of various methods for defining and measuring viscosity based on the Indian Bureau standard definition:

Industrial Viscosity: This term refers to the dynamic viscosity that the cup viscometer measures.
Absolute/Dynamic Viscosity: Vacuum capillary viscometers of various varieties are used to measure it.
Kinematic Elasticity: Different kinds of capillary viscometers are used to measure it.

To conduct a bitumen viscosity test, a sample is typically put into a viscometer, after which the bitumen's flow-out time is determined under specific guidelines. Finally, the viscosity is calculated by dividing the flow time in seconds by the viscometer's calibration coefficient. Based on mm2/s [cSt], the bitumen viscosity unit is calculated.

Why Do We Use the Bitumen Viscosity Test?

The uniformity and stability of the Bitumen is the goal of standard construction. This is obtained by tightly packing the aggregates and adequately filling the gaps between them. Viscosity is a useful characteristic to demonstrate bitumen's coating and adhesive abilities.

Low viscosity bitumen does not attach to aggregates well since it flows and behaves more like a lubricant than a binder.

Additionally, an Bitumen mix that uses a high viscosity bitumen binder will not compact particles evenly. As a result, picking a bitumen with the right viscosity is crucial.

A characteristic that is impacted by temperature variations is viscosity. Engineers evaluate bitumen's viscosity at 60 °C and 135 °C, two different temperatures, for this reason. We can thus forecast the ideal temperature at which bitumen should mix and compact.

The resistance of bitumen to melting and flowing is determined by measuring its absolute or dynamic viscosity at 60 °C.

This test may also be used in place of the softening point test. because the viscosity property is closely related to the softening point test. It also gauges the bitumen's resistance to melting and flowing.

To further understand bitumen's capacity to coat aggregates effectively at higher temperatures, bitumen viscosity measurements are required. Therefore, 135 °C is used to measure the kinematic viscosity.

Here is an illustration of the viscosity value of various grades of bitumen based on sections II and III of the IS 1206 method:

The following is a description of Industrial, Dynamic, and Kinematic Viscosity Tests in accordance with IS 1206 methods I, II, and III:

Bitumen Viscosity Testing using IS 1206
According to IS 1206 sections I, II, and III, the following is a description of the apparatus's components and the test procedure for several types of bitumen viscosity:

Various Techniques for Bitumen Viscosity Testing under International Standards. The viscosity of bitumen can be assessed using the following accepted techniques

Industrial Viscosity

EN 12846-1
EN 12846-2
IS 1206 (I)

Absolute or Dynamic Viscosity

AASHTO T202-03
AASHTO T316-06
EN 12596 dynamic at 60
EN 13302
ASTM D2171
ASTM D4402
IS 1206 (II)

Kinematic Viscosity

AASHTO T201-03
EN 12595 kinematic at 135
IS 1206 (III)
IP 543
ASTM D2170
ASTM D2161
ASTM D445

1. Bitumen Industrial Viscosity Test
A fluid's capacity to obstruct flow is referred to as its industrial viscosity. Utilizing a cup viscometer, it is measured.
In addition to measuring the viscosity of bitumen emulsions, tar and cutback bitumen are also measured with cup viscometers. The size of the drain hole (orifice) of a cup viscometer can be used to categorize it into several categories.

Using a cup viscometer, one may calculate how long it will take 50 ml of bitumen to flow through an aperture of a particular size and temperature in seconds. The next step is to multiply the duration by the viscometer's calibration coefficient to obtain the viscosity value.

1.2. The Industrial Viscometer Test Procedure

Put the tar viscometer in the cup as the first step. Make sure the cup's top surface is level. The water bath should be heated to the test temperature and kept there throughout the test. It is best to gently stir the stirrer.
The bitumen sample needs to be heated by roughly 20 °C above the test temperature. It is necessary to cool the bitumen sample to the required testing temperature. Until the leveling peg on the valve is just submerged, pour the specimen into the cup. Throughout this operation, the valve rod should remain upright..
Use an appropriate solvent to clean the orifice. Fill the graduated cylinder that is positioned underneath the opening of the cup with 20 ml of mineral oil or a 1% by weight solution of mild soap.
In the cup, place the thermometer. Till the tar reaches the test temperature, keep stirring. The thermometer should be placed parallel to the cup in the middle of the tar. Give the device 5 minutes to stand. The thermometer reading should not exceed the designated test temperature by more than 0.05 °C throughout this time. Take the thermometer off. Additionally, make sure to take out any extra samples as soon as you can. When the valve is vertical, make sure the bitumen level is in the center of the leveling peg. On the valve support, suspend the valve.
At 25 ml on the cylinder, start the stopwatch. Once the cylinder reading hits 75 ml, stop the process and record the time in seconds.
Repeat the test several times using the same subject matter. The final result is the average value of the recorded times.
Keep in mind that for repeated measurements, the difference between the greatest and lowest readings should not be greater than 2 seconds if the mean viscosity value is less than 40 seconds. Additionally, the difference between the highest and lowest values for an average value of more than 40 seconds should not be greater than 5% of the mean value.

2. Absolute or dynamic viscosity Test of Bitumen
The internal resistance between moving fluid layers known as dynamic viscosity, also known as absolute viscosity, is brought on by the molecules of the fluid adhering to one another.
Using a vacuum capillary viscometer, it is measured. A capillary (very thin) tube is inserted into the water bath to measure the viscosity. The water bath can be either 60 °C or 135 °C in temperature.
Bitumen is passed through the capillary tube and the amount of time it takes is noted. Viscosity is calculated by multiplying the calibration coefficient by the time.

2.1 Tools for Determining Dynamic or Absolute Viscosity:
There will be a need for the following equipment:
Cannon-Manning Vacuum Capillary Viscometer, Bitumen Institute Vacuum Capillary Viscometer, Modified Koppers Vacuum Capillary Viscometer,
Water bath, Thermometer, Vacuum Pump, Oven, Stopwatch, Stirrer.

2.2. Bitumen Dynamic Viscosity Test Procedure:
Heat the sample until it is sufficiently liquid to pour, which should be done by heating it above its rough softening point temperature. The temperature shouldn't exceed 60 °C or 90 °C for samples of bitumen or tar, respectively.
Fill line E of the viscometer with the sample. For a few minutes, place the viscometer in an oven or a paraffin bath that is kept at 135 °C until the air bubbles disappear.
Place the viscometer upright in the water bath that has been heated to the test temperature. Create a vacuum of 40 kPa at standard pressure using a vacuum pump, then attach the instrument to the viscometer. After 30 minutes, open the valve and allow the bitumen sample to pass through the viscometer. Keep track of how long the bitumen takes to pass between adjacent timing markings. Keep in mind that the duration is greater than 60 seconds.

The recorded time is multiplied by the viscometer's calibration coefficient to provide the viscosity value.

Kinematic Viscosity, third Test of Bitumen
A fluid's kinematic viscosity is calculated by dividing its dynamic viscosity by its density (or mass to volume ratio).

Kinematic viscosity is measured using a capillary viscometer. It comes in two separate varieties:
1. Cannon-Fenske Viscometer (for Opaque liquids)
2. BS U-Tube Modified Reverse-flow Viscometer

3. Kinematic Viscosity, third Test of Bitumen
A fluid's kinematic viscosity is calculated by dividing its dynamic viscosity by its density (or mass to volume ratio).

Kinematic viscosity is measured using a capillary viscometer. It comes in two separate varieties:

Cannon-Fenske Viscometer (for Opaque liquids)
BS U-Tube Modified Reverse-flow Viscometer

3.1. Kinematic viscosity measurement equipment
The following equipment will be required:
Viscometer, Water Bath, Thermometer, Oven, Stopwatch, Stirrer

3.2 The Kinematic Viscosity Test for Bitumen Procedure:
An Example of Preparation
Bitumen cutback Stirring the cutback sample into the container will ensure that it is well-combined. When stirring, take care not to stir up air bubbles. It is preferable to heat a particularly viscous sample to 60 °C before transferring 20 ml to a container with a 30 ml capacity.

Bitumen: Warm the sample up till it turns into a consistent liquid. The needed heating temperature ought to be higher than the softening point. Additionally, the bitumen and tar samples shouldn't be heated above 90 and 60 degrees Celsius, respectively. A 30 ml container should then receive 20 ml of the sample.

The Kinematic Viscosity Test of Bitumen Procedure

Viscometer for Opaque Liquids made by Cannon-Fenske

•Invert the Cannon-Fenske viscometer and apply suction to tube L to fill it. Tube N should be submerged in the liquid sample. Fill bulbs D with liquid through tube N until mark G is reached. Take the tube N's extra sample out. Put the viscometer back in its upright position. In the bath, the viscometer ought to be placed vertically.

•Until the bitumen sample reaches the test temperature, the viscometer should stay submerged in the water bath. After that, open the stops on tubes N and L, respectively, and allow the sample to fall naturally..

•Lastly, time how long it takes bitumen to travel from timing mark E to timing mark F. In the event that this efflux time is shorter than 60 seconds, choose a viscometer with a smaller capillary diameter.

Modified Reverse-Flow Viscometer by BS U-Tube

Install the BS U-tube viscometer in the bath of constant temperature in a vertical position. Sample should be poured through tube N to just above fill mark G. Lavishly permit the sample to pass through capillary R. Pay attention to keeping the liquid column intact till the bottom mark H. Then, stop its flow by fitting a stopper in tube L to the timing tube.
Allow the sample to warm up to room temperature so that the air bubbles trapped in the bitumen progressively rise to the surface and the sample is free of them.
Let the sample flow after removing the stopper. Press back the stopper to stop the flow once it is roughly at the lower filling mark H.
It is necessary to eliminate the extra sample above filling mark G. This is accomplished by inserting the special pipette all the way up until the top of tube N is reached by its stopper. Apply mild suction after that until air is pulled in. The sample's highest level must fall on mark G.
The viscometer must spend enough time in the constant temperature bath for the sample to reach thermal equilibrium.
Next, open tubes N and L's stoppers and allow the sample to fall naturally. Calculate how long it takes for bitumen to travel from timing mark E to timing mark F. In the event that this efflux time is shorter than 60 seconds, choose a viscometer with a smaller capillary diameter.

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