Bitumen for asphalt. Marks and properties of road bitumen

All types of asphalts used to strengthen roadbeds consist mainly of two components: bitumen and mineral crumbs. The latter is manufactured in accordance with the standards of GOST 9128 from very strong materials. Bitumen for asphalt can be used in different brands.

Features of production technology

Natural bitumen lies usually near oil deposits in the form of lenses. However, in industry and road construction the second version of this material is more often used - artificial. Do this bitumen from refined products. Usually it is tar and extracts of selective oil purification.

Composition of asphalt and its varieties

The composition of the mixture intended to cover roads, in addition to bitumen, may include such components as sand and crushed stone. Using the first, sand asphalt is produced. Sometimes a mixture of mineral powder and crushed stone is added to the mixture. This is a very common kind of cover. It is called asphalt concrete gravel. Also this road material is sometimes made using gravel. In the mixture in this case, add crushed stone and mineral powder. Asphalt of this variety is called gravel.

Depending on the purpose of the mixture, the ratio of all these components can vary. So, for pedestrian paths, asphalt is used, made using fine sand and crushed stone. The lower layer of the roadway is usually made from a mixture of slightly different composition. In this case, asphalt is made using only a very large crushed stone. The top layer of roads is flooded with a smoother asphalt. It includes gravel of fine fractions.

Bitumen grade for asphalt

Thus, the type of filler used affects the strength of this type of material, and therefore the area of its application. However, the composition of asphalt and its quality are not less dependent on the brand of bitumen mixed into it. To produce mixtures of this type, a special material of this type is usually used. It is called road bitumen and is marked with the letters BND. The main parameter by which this material is classified is the temperature regime.

Under certain conditions, all bitumens without exception begin to melt. Depending on the point at which this happens, the material can be used in a particular region of the country. In order to determine in what conditions it is possible to use this particular bitumen for asphalt, it is first of all necessary to look at its marking. The figures in it show the viscosity range of this material. Currently, asphalt production uses only five varieties of road bitumen: BND 40/60, 60/90, 90/130, 130/200, 200/300. The hotter the climate, the more viscous the material should be used in the manufacture of paving.

Of course, bitumen in asphalt must be present in sufficient quantities. Too much of this material is usually not used in the preparation of mixtures. Hot composition for road pavement should crumble, not stick together. However, if bitumen is not enough, unfavorable processes begin to occur in the asphalt with time. It penetrates the water and, freezing in the winter, tears it.

Basic properties of BND

In addition to viscosity, bitumen for asphalt is characterized by such properties as:

• Ductility. This indicator is determined by the distance by which the bitumen can be pulled into the thread without breaking it. The higher it is, the higher the stickiness of the mixture. Road bitumens usually have a degree of ductility greater than 40 cm. The requirements for this indicator for BND are set at a temperature of 0 degrees C.

• Deformative characteristics. When determining the suitability of bitumen for the manufacture of asphalt, attention is also paid to such properties as elasticity, creep, plasticity, brittleness, etc. They determine the deformation characteristics of this material. When the bitumen is heated, the latter should not change too much.

Liquid compounds in construction

Bitumen for asphalt usually has a very high degree of viscosity. However, sometimes when pouring coatings and use liquid varieties of this material. They are used mainly to extend the season of road works. Liquid bitumen in certain proportions is added to the viscous. As a result, the coating at low temperatures does not freeze too quickly. Liquid bitumen from viscous is produced by adding distillate fractions.

When carrying out repairs, a medium viscosity material is also used. It is used to process an already cleaned card. The rate of bitumen consumption for asphalt laying in this case is not too large and is only 0.5 l / m ² .

What supplements can be present in the BND

In the production of bitumen road, in addition, all kinds of additives can be used. They are needed to change certain properties of this material. For example, in the manufacture of cold asphalt, bitumen is used, which includes modifying components. As a result of their use after hardening, the coating does not crack in the cold and does not melt in the heat. When using MAK additives, bitumen acquires its final properties much faster.

What is added to bitumen for asphalt yet? A very interesting version of this material is obtained if colored mineral powders are used in the process of its production. From such bitumen it turns out very beautiful asphalt. Lay it in parks, on bicycle paths, and also use for marking.