What is Bitumen?

The term bitumen refers to a substance produced through the distillation of Crude oil. Bitumen is known for its waterproofing and adhesive properties and is commonly used in the construction industry, notably for roads and highways. Production occurs through distillation, which removes lighter crude oil components like gasoline and diesel, leaving the heavier bitumen behind.

Bitumen is a byproduct of crude oil. It is commonly produced through a refining process in which crude oil is reduced. It removes lighter crude oil components and leaves behind the heavier bitumen. This product has many industrial applications. It is used in the construction of roads, where it is known as asphalt, and in roofing.

Properties of Bitumen

  • Adhesion: Bitumen is capable of adhering to a solid surface in a fluid state depending on the type of the surface. The presence of water on the surface prevents adhesion.
  • Resistance to Water: Bitumen is known as a water proof substance. Under some conditions water may be absorbed by adding slight amount of inorganic salts in the bitumen or filler therein.
  • Hardness: To measure the hardness of bitumen, the penetration test is carried out, which measures the depth of penetration a weighted needle in tenths of mm. of bitumen after a given time, at a certain temperature (generally a weight of 100 gm is applied for 5 sec at a temperature of 77 °F). The penetration is a measure of hardness. Typical results are 10 for hard coating asphalt, 15 to 40 for roofing asphalt and up to 100 or more for water proofing bitumen.
  • Viscosity and Flow:The viscous or flow properties of bitumen are of importance both at high temperature during processing and application and at low temperature to which bitumen is subjected during service. The flow properties of bitumen vary considerably by temperature and stress conditions. Deterioration, or loss of the desirable properties of bitumen, takes the form of hardening which, consequently, decrease the adhesive and flow percentage and an increase in the softening point temperature and coefficient of thermal expansion.
  • Softening point: Softening point is the temperature at which a steel ball be thrown at a known distance through the bitumen when the test subject is heated at a known rate. Usually the test consist of a 3.8-cm-diameter steel ball, weighted 3.5 gm, which is allowed to sink through a 5.8 cm in diameter, 1.4 cm in thick disk of bitumen in a brass ring. The whole subject is heated at a rate of 9 °F per min. Typical values would be 240 °F for coating grade asphalts, 140 °F to 220 °F for roofing asphalt and down to 115 °F for bituminous water proofing material.
  • Ductility: Ductility test is conducted to determine the amount at which bitumen will stretch at temperature below its softening point. A briquette having a cross sectional area of 1 in 2 is placed in a tester at 77 °F. Ductility values ranges from 0 to over 150 depending on the type of bitumen.

Bitumen Uses

The product has several modern uses. It's generally meant for industrial use and is commonly found in road paving. The majority of U.S. roads are made of either bitumen or a combination of bitumen and aggregates, such as concrete.

Bitumen is primarily used for industrial purposes. It can be found in the construction industry where it is used to make roads, which is why it is commonly called asphalt in this application. It also has waterproofing and adhesive properties, which makes it a good product for roofing.

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