Blown bitumen
In order for petroleum bitumen with high degree of softness to have elasticity even in cold,
they blow air into it to oxidize. The result is blown bitumen about which we will talk in this article. Generally, blowing hot air into the pure bitumen in the final stage of the filtration process results
in a blown bitumen (Rubbery Grade). In this process, hot air at a temperature of 200 to 300 ° C blows into the chamber containing the bitumen through perforate pipes. As a result of this process, the hydrogen atoms in the molecules of bitumen hydrocarbons combine with the oxygen in the air,
and with the formation of water, the polymerization takes place and bitumen with the properties of mineral bitumen appears.
Types of bitumen
In general, the types of bitumen are in four general categories as follows:
The first category is solid bitumen types, which are directly from crude oil refining. Besides, solid bitumen types’ names are according to the degree of penetration and different types.
Including:
60/70, 85/100, 130/150, 180/200, 250/220, 280/320
Also, by blowing air into the above bitumen types at high temperatures,
other grades of bitumen such as 30/20, 40/50 bitumen and in some cases 70/60 bitumen can appear.
The second category of bitumen includes oxidized solid bitumen or blown bitumen,
which indicate this type of oxidized bitumen with the symbol R. To be more specific, oxidized bitumen grades or blown bitumen
types are the result of blowing air into a mixture of heavy oils and bitumen and their name are according to their softening point and degree of permeability.
The third category is modified bitumen,
which is commonly applicable in the road construction and insulation industry or isogum. As an example, the production of 70/70 modified bitumen is by mixing (vacuum bottom (VB) with natural bitumen (Gilsonite)
without the need for aeration. Since the price of natural bitumen is low, modified bitumen can be economical. In addition, modified bitumen have more
resistance to climate change and their adhesion to minerals is very good. Importantly, improved bitumen in the northern regions of the country, which are very prone to wear,
play an important role in increasing the life of road asphalt.
The fourth category is polymer-modified bitumen types. In polymer-modified bitumen types, they try to improve the properties of bitumen
by mixing one or more polymers with bitumen.