What is bitumen? And what materials is it obtained from?
First, we will explain the concept of bitumen. In fact, we can say that bitumen is a black and dark brown solid. This solid substance is completely soluble in carbon sulfur and tetrachlorocarbon. As mentioned, it exists in a solid state at room temperature, and as the temperature increases, it becomes a paste and becomes liquid after a while. One of the important properties and characteristics of bitumen that makes it have significant applications is its impenetrability to water and high adhesion.
Pure bitumen is the bitumen that is extracted from oil or special minerals. According to the extraction source, it is placed in different categories. However, after the process of extracting pure bitumen, it must be subjected to different processes in order to be usable. These processes convert different types of bitumen into different forms of blown bitumen, soluble bitumen, non-emulsion bitumen, polymer bitumen, etc.
The history of the use of bitumen
At the beginning of the bitumen industry, or in other words, the application of bitumen, it was spread in the form of powder on the surface of the roads, and this technique has been quite successful. Of course, after a short time, the heated powder eased the asphalting of the roads. With the advancement of technology, the use of bitumen in the fields of road construction, floor covering, roofing, underground pipes, use in the construction of isogam, canals and bridges, and painting expanded.
Getting to know the types of bitumen
Among the types of bitumen, we can mention petroleum bitumen, natural bitumen, blown bitumen, mixed bitumen and emulsion bitumen, each of which has its own characteristics and production conditions. We will briefly explain each of the different types of bitumen:
1- Petroleum and natural bitumen
As mentioned, it is usually obtained from the distillation of crude oil and various minerals. The product is obtained from two stages of crude oil distillation in the distillation tower. At a pressure close to atmospheric pressure, the distillation process continues. Then those heavy compounds and kerosene are removed. Finally, a mixture of very fine particles that have turned into a solid state remains. These particles are immersed in the fluid like grease.
Natural bitumen is obtained in nature as a result of the conversion of crude oil after long periods of time. That is why it is named like this. Iran’s Behbahan Bitumen Lake and a lake called Trinidad Bitumen Lake in America have natural bitumen.
2- Blown bitumen
It is obtained by blowing hot air into the pipes. Very hot air with a temperature of 200 to 300 degrees Celsius is blown through mesh pipes. By doing this, the hydrogen and oxygen atoms of the air combine and create water. In terms of penetration degree, blown bitumen is less penetrating than other types of bitumen. It also shows less sensitivity to changes, which indicates the quality and impressive level of application of blown bitumen. The abbreviation of blown bitumen is represented by the English letter R.
3- Mixed or soluble bitumen
Mixed or dissolved bitumen becomes liquid at high temperature. The speed and time required for the bitumen to harden depends on the type of solution that is added to the bitumen. For example, due to the high evaporation rate of gasoline, the hardening of bitumen whose solution is gasoline is faster than other types of mixed and soluble bitumen. But the rate of evaporation of oil is low, as a result, bitumen whose solvent is oil hardens more slowly.
4- bitumen emulsion
To make emulsion bitumen, mix enough emulsion material and water. Of course, it is said that the amount of emulsion is very low and is approximately 3-5% of the bitumen weight. The maximum amount of bitumen used is 30 to 50% of the weight of bitumen. In making bitumen emulsion, the emulsifier can usually be ammonium salt, organic acid, or alkali; which causes bitumen particles to become charged.
The use of bitumen emulsion has many benefits, including the reduction of environmental pollution. Another use of emulsion bitumen is its use in the field of cold asphalt in wet environments or insulation.
Some of the best features of emulsion bitumen
In the following, we will mention some features of emulsion bitumen:
- Emulsion can be used in asphalt with low thickness.
- There is no need for heating during the storage of emulsion bitumen or the initial start-up.
- Due to the fluidity of bitumen emulsion, its permeability is suitable.
- Bitumen emulsion is free of any toxic substances.
- It is not capable of igniting or igniting during execution.
- We will not need complicated tools and machines to set up and implement bitumen emulsion.
- Emulsion bitumen changes color from brown to black after the breaking process and is ready for traffic in a short time.
Technical and qualitative specifications of bitumen in different types
By knowing the characteristics and technical specifications of bitumen, you can recognize the quality and guarantee the health and useful life of the product.
Degree of penetration
The lower the penetration in millimeters, the harder the resistance and the higher the quality and use of the bitumen.
By using Cbolt Fiorel device, it is possible to determine the fluidity of bitumen, but it is clear that the fluidity of the product decreases at high temperatures.
Degree of ignition
The maximum temperature that bitumen can withstand in the workshop is known as ignition degree.
Bitumen is one of the important and fundamental characteristics. This property is usually measured at a temperature of 163 degrees Celsius and a period of 5 hours (asphalt curing temperature).
And among the other characteristics of bitumen, we can mention malleability, degree of purity and softness.
Factors affecting bitumen quality grading
Solid bitumens are classified or graded based on characteristics such as permeability, oxidation, viscosity or efficiency, for example:
The bitumens obtained from the distillation of crude oil are softer and are of better quality than the bitumens which are composed of several types of metals with aeration.
Application of bitumen in different fields
In general, the following can be mentioned from the applications of bitumen:
• Road Construction
• Industrial applications
• Waterproofing of commercial and residential buildings
• Electrical insulation
Of course, it should be noted that the main use of bitumen is seen in road construction, and in later stages, it is used as a moisture insulation as the main material in the construction of insulation under the name of Izogam.
90% of bitumen is used in road construction and only 10% is left for other uses.
Application of bitumen in work insulation
Another use of bitumen is usually used for insulation in different parts of the building, such as the roof and bathroom floor. You must have heard that “it is better to use bitumen in a bitumen form” this means that in order to stabilize the bitumen and isogam work of the building, in order not to need an isogam repairman shortly after installing the isogam, it should be used together with a sack. This stabilizes the infrastructure.