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What are the Differences Between Bitumen, Tar and Asphalt?

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What are the Differences Between Bitumen, Tar and Asphalt?

Bitumen, tar, and asphalt often get confused with each other. They come from different sources and behave differently. Here's a clear, side-by-side comparison of all three.

mozhdeh-darbandi
mozhdeh-darbandi
Published in Sep 14, 2020
What are the Differences Between Bitumen, Tar and Asphalt?

Bitumen, tar, and asphalt often get mixed up, but they're not the same material. Bitumen and tar are close cousins, while asphalt is something else entirely: a mix of bitumen and stone, not a pure substance on its own.

Below, we compare all three across the things that actually matter: where they come from, what they're used for, how much they cost, and how they behave physically and chemically.

Difference in Origins

Bitumen 

The bitumen has two origins. 

Bitumen comes from two places: the refinery, or the ground.

Refinery bitumen starts as crude oil, heated in a distillation tower to between 300°C and 350°C. This separates out the lighter parts of the oil, leaving behind a thick, sticky residue called vacuum bottom. That residue is the raw material used to make bitumen.

Natural bitumen, on the other hand, is mined directly from the ground. This solid form is called Gilsonite.

Tar 

Tar comes from a different process altogether. Producers heat organic material, like coal, wood, or peat, without any air present. This is called destructive distillation, and it's what turns the raw material into tar.

Asphalt

Asphalt isn't a raw material at all. It's made by mixing bitumen with aggregates like sand and stone, either at a factory or right at the construction site.

Differences in Applications

Bitumen 

Bitumen has more than 130 applications in different industries. More than 85% of bitumen application is in the road construction but it can also be used in waterproofing, roofing and coating.

You can read the list of bitumen applications in the Bitumen Applications and Uses page.

Tar

Tar also has different applications as below:

  • Pavement sealer
  • Roofing material 
  • Wood preservative
  • Medicinal applications for eczema and skin treatment 
  • Industrial applications like making plastics and rubber

Asphalt 

Asphalt just can be used on the road surface. It doesn’t have any special application in other industries.

Difference in Price 

These three material prices can be determined based on different factors including the market supply and demand, quality and their grades.

But generally, the bitumen price is lower than both tar and asphalt. 

Tar has a high price compared to bitumen because usually its supply quantity is less than bitumen. 

Sometimes, due to the raw material prices of asphalt, the asphalt price can be more than bitumen and tar.

Differences in Physical Properties

Generally, these three materials have differences in the below physical properties: 

  • State
  • Color
  • Density
  • Melting Point
  • Boiling Point

State

Bitumen state can be in the liquid form with different viscosities or a brittle solid. Tar is a liquid with high viscosity and the asphalt has a solid composition that its viscosity is too high.

Color

The color of bitumen is dark brown or black which indicates it has the components of asphaltene and resins. Tar color is dark black due to the high carbon content.

Asphalt color depends on the aggregates and its binder which is bitumen. Currently, in some countries different types of asphalt with different colors are produced.

Density

The density of bitumen is in the range 1.01-1.05 g/cm³ in the temperature range of 25°C to 85°C. 

Tar density in this temperature is higher than bitumen and is in the range 1.15 to 1.4 g/cm³. 

The asphalt density is 2.2 to 2.4 g/cm³. The higher the density of the asphalt, the more durable it is. 

Boiling Point

The boiling point of tar can range from 100°C to 400°C, depending on its composition and the method of production. Bitumen boiling point is in the range 200°C to 525°C and the asphalt boiling point is typically around 400°C to 500°C. 

Melting Point

Generally, these substances don't have a clear melting point like a solid substance. When they become increasingly viscous as they are heated, they eventually become liquid. 

But, the probable melting point of these three material is as below:

  • The melting point of bitumen is around 120-150°C 
  • The melting point of tar is around 42-46°C 
  • The melting point of asphalt is around 135-165°C 

Differences in Chemical Properties

Bitumen, tar and asphalt have differences in the below chemical properties: 

  • Carbon Content
  • Reactivity
  • Flammability
  • Water resistance
  • Acid resistance
  • Adhesive power
  • Setting time

Carbon Content

The carbon content of bitumen and tar is more than asphalt. Generally, bitumen has lower carbon content in comparison to tar but 80% to 90% of bitumen is carbon.

Bitumen with a higher carbon content may be more viscous and hard, while bitumen with a lower carbon content may be less durable and more susceptible to aging and weathering.

On average, tar contains between 50% to 90% carbon. Asphalt carbon content depends on the type of bitumen that is used to bind the aggregates.

Reactivity

In general, bitumen is a relatively inert material in the ambient temperature and has low reactivity but when it is exposed to certain conditions, such as high temperatures or exposure to oxygen, bitumen can undergo chemical reactions that can cause it to degrade or become more reactive.

Tar is also the same as bitumen that has low reactivity. But sometimes it can react with other chemicals such as oxygen, nitrogen oxides and sulfur dioxide in the environment. These reactions of tar and chemicals can lead to the formation of secondary pollutants such as acid rain.

Asphalt can react with oxygen, water, and acids which can cause changes in its resistance against the cracking.

Flammability

Generally, according to the flash and fire point test of bitumen, bituminous materials have a high flammability. Their flash point is in the range 200 °C  to 300 °C  and the fire point is between 250 °C to 350 °C.

Tar is flammable too, it can be ignited by spark and friction. Its flash point is in the range 150 °C to 300 °C while its fire point is 200°C to 400 °C.

Asphalt itself is not flammable but the protective asphalts that are cut back bitumen can be flammable because there exists petroleum based solvent in its composition.

Water Resistance

The water resistance of asphalt and bitumen is high, but tar has less water resistance in comparison to these materials. 

Acid Resistance

Compared to bitumen and asphalt, tar is generally more resistant to acids. This is because tar is typically made from coal or wood and contains a higher percentage of aromatic hydrocarbons than either bitumen or asphalt. These hydrocarbons have a greater resistance to chemical degradation, including acid attacks.

Bitumen and asphalt, on the other hand, are both derived from petroleum and contain fewer aromatic hydrocarbons than tar. As a result, they are generally less resistant to acid attacks than tar. However, the exact level of acid resistance can vary depending on the specific type and quality of the material used.

Adhesive Power

One of the main reasons that bitumen and tar are used in waterproofing, insulation and sealing is their adhesive power. The asphalt itself has no adhesive power but the bitumen and tar have a strong adhesion. Bitumen adhesion is less than tar and tar adhesion is too high.

Setting Time

In comparison to bitumen and asphalt, the setting time of tar is high. 

Generally the setting time of bitumen depends on its grades, temperature and wind. For example, the setting time of bitumen emulsion CRS-1 is higher than the CMS-1. 

Asphalt setting time is too low and it takes time for asphalt to be set on the surface.

Bitumen vs Asphalt: What's the Real Difference?

Bitumen and asphalt are not the same thing, even though people often use the two words for the same material. Bitumen is a thick, sticky liquid binder, while asphalt is the finished mixture made by combining bitumen with sand and crushed stone.

Part of the confusion comes from location, not chemistry. In the UK, Europe, and most of Asia, people use "bitumen" for the binder and "asphalt" for the paved mixture, just like we do in this article. But in the US and parts of North America, "asphalt" is often used to mean the binder itself, the same thing the rest of the world calls bitumen.

This matters more than it sounds for buyers and exporters. If a US buyer asks for "asphalt," they usually mean bitumen in drums or bulk, ready to be shipped. If a European or Asian buyer asks for "asphalt," they mean the finished road mixture, which is made locally and can't be exported. Knowing which one your buyer means can save a lot of confusion in a trade deal.


Here's a quick summary of the three materials side by side:

FeatureBitumenAsphaltTar
What it isA sticky liquid or semi-solid binderA mix of bitumen, sand, and stoneA liquid from burning coal or wood
Made fromCrude oil (or found naturally)Bitumen + aggregatesOrganic material, heated without air
Where it's usedRoads, roofing, waterproofingRoad surfaces onlyRoofing, sealants, some medical uses
Can it be exported?Yes, in drums, bulk, or tankersNo, made fresh near the job siteYes, though far less common in trade
Typical priceLowest of the threeCan be higher due to aggregate costsUsually the most expensive

To see it in higher resolution, click here.

Differences Between Bitumen, Tar and Asphalt

At Infinity Galaxy, we supply refinery bitumen in all major grades, ready for export in drums or other packages. See our full bitumen range and request a quote.

Frequently Asked Questions

Is asphalt the same as bitumen?


No. Bitumen is the sticky liquid binder, and asphalt is the finished mix of bitumen with sand and stone. But in the US, "asphalt" often means the binder itself, so the answer can depend on where you're asking.

Why do people confuse bitumen and asphalt?


Mostly because of location. The UK, Europe, and Asia use "bitumen" for the binder, while the US uses "asphalt" for the same thing. Both are correct in their own region.

Is bitumen or tar more expensive?


Tar is usually more expensive than bitumen, mainly because it's harder to produce in large amounts. Asphalt price depends on the cost of the aggregates used with it.

Can bitumen, tar, and asphalt all be recycled?


Bitumen and asphalt can both be recycled and reused in new road projects. Tar is recycled far less often, partly because of its different chemical makeup.

Which one should I buy for export: bitumen or asphalt?


Bitumen is the one you can export. It ships in drums, bulk, or tankers. Asphalt is made fresh close to the construction site and isn't practical to ship internationally.

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