Bitumen is a material widely used in construction, characterized by excellent hydrophobic and adhesive properties. It is mainly used for paving roads. Also very often this material is used as a waterproofing agent in the construction of buildings and structures. In this article, we will understand in detail what bitumen is, what its properties and scope are.
Definition
Bitumen is a dense, viscous, resinous substance of black color. It is usually delivered in pieces that are melted at high temperatures before use . The composition of bitumen is very complex. It is a combination of a hydrocarbon base with its derivatives, as well as metals, oxygen and nitrogen. Various heteroorganic compounds are also present in this material. In general, the composition of bitumen is so rich that the identification of all its components is simply impossible.
How is it made
The main product used for the preparation of bitumen is oil. There are only three main ways of producing this material:
- Concentration of oil residues by vacuum distillation. The final product is soft and fusible. By this technique, bitumens are obtained from highly resinous (sulfur) oil.
- Oxidation of tar (oil residue) by blowing it with oxygen at a temperature of +180 ... + 300 degrees. With this method, a thermostable elastic material is obtained.
- Mixing residual and oxidized oil products with distillates.
Natural bitumen
Most often, this material is produced artificially using the three technologies described above. However, there is natural bitumen, the characteristics and application of which are about the same as that of ordinary. It lies in nature in oil fields and forms a kind of lens. In its pure form, natural bitumen is practically not found. Most often, it impregnates some kind of sedimentary layer. Typically, these are rocks such as sandstone or limestone. In this case, pure natural bitumen is obtained by previously grinding the stones. Sometimes such asphalt rock is simply carefully frayed and used in road construction.
Types of Bitumen by Use
By scope, this material is divided into four large groups:
- Building bitumen. It is used for waterproofing walls, foundations, wooden structures immersed in the ground, etc.
- Roofing. It is used to protect roofs of residential, industrial and public buildings from moisture.
- Road bitumen. The most common option used for the preparation of asphalt.
- Insulating. It is used to protect against moisture and corrosion of metal pipelines.
Road bitumen
In the construction of highways, this hydrophobic material is used most often. There are two main types of road bitumen:
- Viscous. Obtained from oil.
- Liquid. This variety is made from viscous bitumen. In this case, petroleum products are used as a diluent.
Viscous oil road bitumen is used in the construction of highways in the warm season. Liquid material is used in the cold season. Viscous bitumen before laying is heated to the melting point. Liquid material can be used both in cold form and in heated. Some time after laying, due to oxidative processes, such bitumen thickens and gives a dense, moisture-proof elastic film.
What characteristics should you pay attention to when buying
There are only three main parameters by which you can determine the quality of bitumen:
- softening point;
- ductility (the degree of ductility of a bitumen thread);
- penetration (viscosity).
The last indicator is determined by immersion in a bitumen needle or cone at a certain temperature.
Marking
It is very easy to find out what bitumen is for what type of work. To do this, look at the markings.
- Construction bitumen is marked with the letters BN.
- Road - BN or BND.
- Roofing - BNK.
After the letters in the marking are two numbers through a slash. The first number indicates the softening temperature, the second indicates the degree of viscosity. The latter is determined by immersion in bitumen needles at a temperature of 25 about C.
Viscous Road Bitumen Grades
As already mentioned, such material is supplied in pieces or in barrels. When asphalting, BN (oil) and BND (road oil bitumen) are used. According to GOST, only ten types of this material are produced (BDN from 200/300 to 40/60, BN from 200/300 to 60/90).
Liquid road bitumen
This material is marked separately. There are only two of its varieties:
- SG - thickening at medium speed.
- MG - thickening slowly. This variety is used in road construction in climatic zones II-V.
After the letters in this case, two numbers also follow the slash, indicating the acceptable range of ductility (at a temperature of 60 ° C with a 5 mm hole in the viscometer).
When buying a batch, you need to check the certificate (passport) for bitumen oil road liquid. The SG brand, just like MG, BDN and BN, must comply with GOST +. We will talk about what this document is below.
Bitumen Safety
When using this material should be careful enough. Bitumen is flammable. The fire hazard of a particular brand is determined by such an indicator as flash point. In viscous building, road, roofing and insulating bitumen, it is higher, in liquid - lower. Therefore, when working with the latter should be especially careful.
Among other things, when performing operations related to the application, storage, transportation, etc. of bitumen according to the rules of industrial safety, it is necessary to wear special clothing. This protects the worker from getting heated, hard-to-wash drops on the skin.
Bitumen quality certificate
Bitumen sold by enterprises must comply with GOST 2245-90. However, today many companies produce products of this type with improved characteristics. Therefore, special certificates certified by the heads of laboratories, also called passports, are attached to the bitumen of one or another new brand. They indicate such parameters as penetration, ductility, softening point of the product, etc.
Such a document is issued not only for viscous, but also for bitumen, oil road liquid MG. The quality certificate is a guarantee of compliance with the characteristics of the material declared by the manufacturer. The document must be affixed with the seal of the enterprise.
Of course, there must be a passport for bitumen liquid petroleum road SG, as well as for roofing and insulation. The new brands of this material include, for example, BND-U and Euro BV. In relation to them, quality standards are determined not by GOST, but TU and STO. In the production of Euro BV, the requirements of the European standard EN 12591 are also taken into account.
The most common brands
In construction, the most commonly used bitumen is oil road 90/10. Manufacturers produce and sell it in huge quantities. With its help, waterproofing foundations, underground parts of wooden supporting structures, interpanel seams, basements and walls. From another fairly popular brand, BN 70/30, it is distinguished by a higher melting point. This expands the scope of its use, since the film given to them is able to withstand high heating temperatures.
In the construction of highways, the oil bitumen MG130 / 200 is often used. It is usually used in regions where the air temperature in winter does not drop below 20 ° C. This material forms a reliable and very even road surface.
Next, we present to the reader a table with the main characteristics (according to GOST) of these two varieties of bitumen.
| BN 90/10 | MG 130/200 |
Softening Point ( o C) | 90-105 | Residue after evaporation of the thinner - 30 |
Flash point | 240 | 110 |
Ductility | At a temperature of 25 about 1 cm | 131-200 at 60 and hole diameter 5 mm |
Penetration | At a temperature of 25 ° C - 5-20 | - |
Amount of evaporated thinner | - | Not less than 5% |
Road, construction, and roofing bitumen are materials on the market that are in high demand. It is released by many companies today. Therefore, choosing a quality product will be completely uncomplicated. The main thing is to pay attention to the marking and buy the most suitable option in this particular case.