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53IMPROVING THE DURABILITY OF ASPHALT-CONCRETE
Bakhromjon Adhamovich Muxtasar Isrolijon qizi Ikromjon Aminjonovich Otakulov Karimova Abdullayev
Fergana Polytechnic Institute
ABSTRACT
The article discusses the issues of increasing the durability of asphalt-concrete in the climatic conditions of the country, the preparation, laying, compaction and use of asphalt-concrete or cement-concrete mixtures.
Keywords: road asphalt-concrete, compaction, paving, hot asphalt-concrete brand III-IV, polymer compound
INTRODUCTION
The share of secondary materials and waste in the development of the national economy, especially in the construction industry, is growing. On this basis, our scientists make proposals for the production of new and effective building materials. One of the secondary materials is the old asphalt-concrete, which over the years has been piled on top of our urban and rural roads, raising the road surface. The climatic conditions of the country require the development of technologies with a scientific approach, such as increasing the durability of asphalt-concrete, preparation, laying, compaction and use of asphalt-concrete or cement-concrete mixtures. Light asphalt-concrete paved roads are widely used in the construction of roads of I-IV categories in dry and hot conditions. For the asphalt-concrete layer, which is used in the construction of capital roads, and requires an improved multi-cost, hot water of the I and II grades is used, and for the hot asphalt concrete of the I grade. MAIN PART
Hot asphalt concrete of III-IV brand is used for the lower layer of the road, asphalt-concrete of II-IV brand is used for warm and I-II brand is used for cold road. After a thorough study of dry-hot climatic conditions, the type of binder bitumen for asphalt-concrete is selected. In this case, mainly YNB 40/60 and YNB 60/90 road oil bitumens (YNB) are used. It is also possible to dilute YNB 40/60, YNB 60/90 brand bitumens in solvents.
In order for our roads to be of good quality, it is necessary to control the perfect performance of the subsoil from a depth of 80-90 cm to the surface in accordance with the requirements of GOST. Figure 3.3 below shows a schematic of the main asphalt-concrete layers of categories I-II. The thickness of the layers depends on climatic influences and species. Built on the basis of quality building materials and innovative technologies, such roads will not deteriorate for 20 years due to their structural
properties. Only the upper part of it needs to be reconstructed with 2-3 cm thick asphalt-concrete.
In the climatic conditions of Uzbekistan, the recommended parameters for the asphalt-concrete layer are given in Table 1.
Asphalt-concrete used in Uzbekistan Table 1.
Asphalt is a type of concrete A series of highways
I, II, III a III, IV a IV
A / b mark Bitumen brand A / b mark Bitumen brand A / b mark Bitumen brand
It's hot I YNB 4060 YNB 60/90 II III YNB 40-60 YNB 60/90 YNB 90/130 YNB 40-60 YNB 40/60 IV HHE 40-60 HHE 60/90
Cold Not used I O'Q 70/130 II y K 70/130 C K 70/130
These days, in order to further improve the quality of asphalt-concrete roads, scientists of the republic are carrying out scientific and practical work in the following areas. In particular, the Tashkent Institute of Motor Roads, Tashkent Institute of Architecture and Construction, the Institute of General and Inorganic Chemistry of the Academy of Sciences of Uzbekistan are working on the production of activated powders from local mineral stones, the use of road polymer-bitumen compositions, improved asphalt-concrete composition. In increasing the heat resistance of asphalt-concrete with polymer additives, it is especially important to strengthen its structure, to ensure that the porous walls are resistant to environmental influences. For the first time, scientific and practical work to increase the durability of asphalt concrete in a hot-dry environment was aimed at improving its properties by adding natural rubber to it. The subsequent creation of synthetic rubber led to a reduction in the cost of rubber. This has provided economic benefits in improving the quality of roads. With each passing year, the demand for the structural strength of roads and the further reduction of their cost has increased. Broken car tires were recommended instead of synthetic rubber. As a result of further expansion of the scale of road construction, new polymer compounds have been recommended by scientists. In particular, positive results have been obtained on the possibility of increasing the durability of asphalt concrete when using butadiene styrene chloroprene rubber, polyisobutylene and other rubber-like synthetic polymers. The polymer compound should mix easily with the asphalt-concrete composition. This strengthens the asphalt-concrete structure, increasing its density.
CONCLUSION
There are many ways to add polymer compounds to molten bitumen or asphalt-concrete mix. The main is to add the polymer to the bitumen or mineral filler heated to 150-170 ° C, to add the polymer diluted in the solvents to the hot bitumen solution, and so on. The cost of polymer compounds is expensive. For this reason, polymer-bituminous asphalt-concretes are used in road construction of great importance. However, if we take into account the high durability of such asphalt-concrete, that is, the reduction of annual repairs, the fact that they are not damaged for many years, reduces the cost and increases the economic efficiency. Among them, scientists of the Institute of General and Inorganic Chemistry of the Academy of Sciences of Uzbekistan added the SPEOP polymer compound TAYI (Khojimetov N, Kasimov I) to asphalt concrete and increased its resistance to sliding in thick and liquid conditions. The use of rubber powder to improve the quality of asphalt concrete has become widespread in road construction. Every year, the country has a large stock of obsolete car tires. When preparing the rubber-bituminous asphalt-concrete mixture, the heating time at high temperatures should not exceed the norm. Otherwise the bitumen rubber mixture will wear out quickly at high temperatures. Flexibility disappears, fragility increases.
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