Bitumen is one of the oldest building materials known to mankind. Nowadays, its use involves a variety of options. There are many varieties of this material.
Varieties
Bituminous substances are organic materials, which include several types.
- Natural bitumen. It is a viscous substance or a solid material that consists of compounds of carbohydrates and their derivatives. The ways of their formation are natural oxidative processes of oil polymerization. They are common in oil locations. Pure natural bitumen is a rather rare substance.
- Asphalt varieties. This type is found more often than the previous one. It is located in porous rocks. They grind and turn into powder. So road bitumen turns out.
- Oil. This is an artificial kind of material. It is obtained in the process of oil refining. In accordance with the type of technological cycle, such bitumen is divided into residual, oxidizing and cracking.
Composition
Bitumen has the following composition in the classic version:
- up to 80% carbon;
- up to 15% hydrogen;
- from 2 to 9% sulfur;
- no more than 5% oxygen;
- from 0 to 2% nitrogen.
The listed substances are in the form of compounds of hydrocarbons, sulfur, oxygen and nitrogen.
All elements can be classified into three groups.
1. The solid component is high molecular weight hydrocarbons called asphaltenes. Solid components include paraffins.
2. Resins - amorphous materials that have a dark brown color.
3. Oil fractions are various hydrocarbons that have a density of less than 1.
Bitumen is a rather complex substance with a certain ratio of all components. An increase in its mass of asphaltenes will lead to an increase in hardness, brittleness, and softening temperature.
Paraffins also reduce the plasticity of bitumen, therefore, during production, attention is paid to reducing their content to 5% or less.
Application area
Depending on the physical properties, the following areas of application of bitumen are distinguished:
- road construction;
- roofing device;
- waterproofing;
- electric cable production;
- tire and rubber technology;
- batteries
- paint and varnish products;
- metallurgy;
- production of coal briquettes;
- oil refining.
In carrying out construction work on its own, bitumen is the most sought-after material for waterproofing various objects, especially cellars and cellars.
Oil road
In the construction of roads used bitumen oil road (GOST 22245-90). There are several brands of such material.
To choose the right variety, you should determine the type of climate zone.
For natural conditions, which are characterized by temperatures in the cold season on average not higher than -20 ˚, road bitumen such as BND 200/300, BND 130/200, and BND 90/130 are suitable in accordance with GOST.
For regions where average temperatures in the cold season are from -10 to -20 ˚, oil bitumen II and III climatic road zones are provided. These include the above varieties, as well as BND 60/90.
If the average monthly temperatures in the cold season are in the range from -5 to -10 ˚, then GOST provides for the use of such oil road bitumen as all of the above types, as well as BND 40/60, BN 90/130, BN 130/200 , BN 200/300.
For terrain in which winter is characterized by monthly average temperatures of at least + 5 ° C, oil road bitumen of such types as BND 40/60, BND 60/90, BND 90/130, BN 60/90, BN 90/130 are suitable.
Oil
There are varieties that are used for the construction of not only roads, but also residential facilities. These are universal brands. There are only three brands, which include such oil bitumen as BN 70/30, BN 90/130, BN 50/50.
As well as oil road bitumen, GOST which regulates the conditions for the use of each variety, GOST 6671-76 applies to building bitumen.
The lower the ambient temperature, the more flexible the material must be used for construction. This will ensure its durability and durability.
Oil Roofing Materials
For various roof installation works, special bitumen is used. Its properties and scope are regulated by GOST 9548-74. This standard implies the use of three varieties of this roofing material:
- BNK 90/30 - has such a scope as the formation of a roof covering layer.
- BNK 40/180 - used for impregnation.
- BNK 45/190 - selected for processing the roof and obtaining material for the roof.
Factors affecting the type of road material
Road bitumen, GOST which provides for several types of such a substance, is characterized by many different properties. Each gives certain qualities to the material.
The most important of them, which determine the scope of application of bitumen, are plasticity, softening temperature, brittleness, flashing, viscosity, adhesive qualities.
High temperatures increase the viscosity of bitumen. Upon cooling, the material loses this quality and at the moment of reaching the thermal boundary it becomes brittle.
The addition of oils to the composition of the material helps to increase ductility. The greater the frost resistance of oil road bitumen, the higher its quality class.
Flash point is also a very important indicator for material such as road bitumen. GOST provides a standard value for this indicator +200 ˚ and higher. The higher the flash point, the lower the fire hazard of the substance.
The adhesion index will help to find out how well the bitumen adheres to the base of the surface. The higher this indicator, the stronger the material holds on the surface.
Material Use Technology
During the construction of roads and other facilities, bitumen heating technology is used. This process is carried out in accordance with certain rules. The technique of using the material is inherent in the characteristics of a substance such as bitumen. GOST reveals its most important properties.
To heat the material used in construction and repair, a special boiler with thick metal walls and a hermetically sealed lid is used. The thickness of the material will allow it to avoid burning.
2/3 of the capacity is filled. Bitumen breaks into small pieces before loading.
Heating is carried out on a small fire, and the material is melted to a homogeneous mass. When foreign impurities appear, they are extracted with a special sieve. The maximum heating temperature is +200 ˚.
At a heating temperature of +160 to +170 ° C, bitumen will melt in about 3 hours. If you increase it to the limit value, the heating process will be only 1 hour.
Road oil bitumen does not tolerate an increase in heating above +200 ˚, because their properties will deteriorate from this. At +220 ° C, coke begins to form.
When bitumen overheats, an unpleasant yellow-green smoke is formed, and when it reaches the limit of +240 ° C, the substance may even flare up. Then the boiler lid is closed to extinguish the flame.
After overheating and flashing, road bitumen becomes brittle and is no longer suitable for construction or repair work.
Storage and transportation
Storage of bitumen occurs in special tanks. They are equipped with mechanisms for mixing the heated substance. This technique should have special ways to supply water vapor to prevent flare-ups of material vapor.
To empty the tanks, a bottom is provided under the slope.
The equipment transporting liquid road bitumen is equipped with special pumps that pump the substance.
If the material is transported in solid form, special collapsible forms are used.
During transportation and storage, all fire safety requirements are ensured, since bitumen is a highly flammable substance. Fulfilling all safety rules, you can not be afraid of unpredictable situations in working with this material. Having studied the properties and varieties of the material, you can competently apply it in the construction of various objects.
Bitumen is a substance possessing such positive qualities as moisture resistance, durability, non-exposure to climatic influences, low sound and heat permeability, as well as low current conductivity. Due to these properties, it is a very popular and reliable building material.