CC BY
9
Odinaev R.K. teacher
Termez Engineering and Technology Institute
Uzbekistan, Termez Yusupjonov M.O.
teacher
Termez Engineering and Technology Institute
Uzbekistan, Termez Alimardonov Sh.E.
student
Termez Engineering and Technology Uzbekistan Institute
Uzbekistan, Termez
FOREIGN TECHNOLOGY IN THE CONSTRUCTION OF ASPHALT
CONCRETE PAVEMENTS
Annotation: This article discusses how to compare the quality of road construction in Europe and the Republic of Uzbekistan, to pay attention to the quality of roads and to test samples of asphalt pavements in the laboratory and determine their service life.
Keywords: Asphalt concrete, crushed stone, bitumen, laboratory, compaction, testing, gravel, quality, standard, mechanism, coating, foreign, technology.
Introduction. Cold asphalt concrete pavements are slippery in rainy weather, so they usually require additional surface treatment. Hot and warm asphalt concretes can be large grains up to 40 mm, medium grains up to 20 mm, and grains up to 15 (10) mm, depending on the size of the gravel, cold asphalt concrete can be only fine-grained or sandy[1].
Prior to laying and compacting the asphalt concrete, the surface of the foundation must be properly prepared. After patching, leveling and cleaning, the surface of the base should be dried naturally with sand heated to 200-250 °C or with special drying machines (heaters). Once the foundation is dry, it is treated with bitumen materials. To do this, the bitumen emulsion must be heated to working temperature or diluted with paraffin. Thermal mixing involves mixing of virgin mix with the old one after its heating and loosening, and fixing of the resulting mix in one layer. Thermal mixing has all advantages of thermal placement and ensures high quality of the reclaimed layer [2]. The Remix Plus (thermal placement) method involves restoration of worn-out asphalt-concrete pavements by fixing two layers in one pass of a remixer (the lower layer made of the recycled mix and the upper layer as an additional layer). The technology involves softening of the old asphaltconcrete pavement with heat to a depth of 60 mm, its loosening, mixing with additives (virgin mix, rock materials,
plasticizers, mineral and organic binders), and placement maintaining necessary pavement leveling; an additional course of virgin mix with a thickness of 3.0...6.0 cm is laid (figure 3).
Asphalt mix istransported by dump trucks from the place of preparation to the place of laying. The main requirement for the organization of transportation is to ensure that hot (100-120 °C)and warm (70-80 °C) mixtures do not cool down. When the air temperature is above 10 °C, the transport time of the hot mixture should not exceed 1.5 hours. The hot mixture can be transported for 2-2.5 hours.
Asphalt concrete is a building material consisting of a mixture of crushed stone, sand, mineral powder and bitumen. Before mixing, they are heated to 100-160 °C. Hot bituminous bituminous concrete laid and compacted at a temperature of not less than 120,, compacted asphalt concrete at 40-80 va and low-viscosity hot asphalt concrete, cold bituminous cold asphalt concrete compacted at air temperature (above 10 °C); It is divided into large, medium, fine-grained and sandy asphalt concrete. Depending on the division, they are used for roads, floors, roofs of industrial buildings and other purposes.
Depending on the quality of the road surface, the technology of road construction works will vary. For example, when laying asphalt concrete, sand is sprinkled on the bottom layer of the foundation, gravel with cement is added on the top layer, and a two-layer mixture of bitumen mineral and asphalt concrete is laid [3].
Discussion. Road construction machines also play an important role in the construction of asphalt pavements. This is due to the fact that if the machines do not give quality work in the construction of coatings, the coating will not be built properly and the service life of the coating will be reduced. It is necessary and necessary to lay the coating on the basis of the established normative
documents. The process of restoring the original properties of the asphalt pavement is called regeneration. He has different ways. Prior to the development of technology for the use of obsolete asphalt concrete, its properties are studied in the laboratory. Cylindrical specimens are cut from long-used asphalt concrete. Bitumen, fine and coarse aggregates are separated and tested [4].
Analysis and results.
Table 1. Laboratory comparison of bitumen.
№ Наименование показателей Метод Требования Результаты
испытаний ГОСТ 2224590 испытаний
1 Глубина проникания иглы, 0,1 мм, не менее, при По ГОСТ 11501
температуре: - 250 С; 61-90 80
- 00 С; 20 22
2 Температура размягчения по кольцу и шару, 0 С, не ниже По ГОСТ 11506 47 48
3 Растяжимость, см, не менее,
при температуре: - 250 С; По ГОСТ 11505 55 74
- 00 С; 3,5 3,9
4 Температура хрупкости, 0 С, не выше По ГОСТ 11507 -15 -16
5 Температура вспышке, 0 С, не ниже По ГОСТ 4333 230 308
6 Изменение температуры размягчения после прогрева, 0 С, не более По ГОСТ 18810 По ГОСТ 11506 5 2
7 Индекс пенетрацин По ГОСТ 22245 -1,0 до +1,0 -0,5
The key direction in research of hot recycling is production of standard asphalt concretes with more than 25% secondary raw material containing bitumen, which requires solving a number of tasks associated with high content of secondary high-viscosity bitumen:
• ensuring heat transfer enhancement during RAM production;
• ensuring combination of the new bitumen and secondary bitumen, which can be achieved through increase in the RAM production duration;
• ensuring proper parameters of asphalt-concrete compaction.
Conclusion. Today, the quality of asphalt pavement construction is
becoming a topical issue. One of the biggest reasons for this is the lack of bitumen. At present, asphalt concrete mixes with the addition of bitumen-substituting secondary raw materials are being prepared at asphalt plants, and samples of these prepared asphalt concrete are being tested in the laboratory. So far, the results are not very good, and as a result of repeated attempts, I think that these attempts will yield results and the construction of quality asphalt
pavements will be achieved. Foreign and Uzbek scientists are working hard to improve these results. It is also advisable to build asphalt pavements as a construction on the basis of normative documents.
References:
[1]. M.Nabiev Q.Tursunov "Specific advantages of asphalt and cement concrete roads".
[2]. A.X.Khabibullayev, M.O.Yusupjonov, Sh.O. Azimjonov "ENSURING CONSTRUCTION QUALITY IN THE CONSTRUCTION OF ASPHALT CONCRETE PAVEMENTS " Euro Asia Conferences. Euro Science: International Conference on Social and Humanitarian Research, Hosted from Cologne, Germany. April 25rd-26th 2021. http: //euroasiaconference.com. Pages: 119-122.
[3]. Д.Махкамов, М.Юсупжонов, А.Хамидов, Оброзование и наука в ХХ веке "Методы получения качественного битума и испытания битума в лаборатория" Настоящий сертификат подверждает публикацию материала в междунарадном научном-образовательном электронном журнале А3-20210517-32 от 17.05.2021г.
