CC BY
2IMPROVING THE QUALITY OF ASPHALT CONCRETE COATING MATERIALS BY ADDING RUBBER PIECES IN THE PROCESS OF
PREPARATION
c.t.s. Ass. Prof. A.Ablakulov PhD student : S.Jamolov Tashkent state transport university
ANNOTATION
In this article, the increase in durability of asphalt concrete pavement by adding rubber pieces was considered. In this process, used car tires are used as rubber pieces.
KEY WORDS
Roads, rubber pieces, road strength, asphalt concrete, rubber pieces. Introduction
The increasing consumption of waste tire has generated many problems such as increasing landfill space, environmental pollution and causing health hazards. Parallel to this is the increasing of roads construction as a result of heavy traffic on roads. This study reviews to the use of crumb rubber (waste tires in powder form) in bitumen using the wet process. The study focuses on the crumb rubber as a replacement to the total weight of bitumen. The design or life span for all highways and urban roads is 10 - 20 years. Unfortunately, damages or distresses on pavements are still occurring before reaching the maximum period of the designed road serviceability. Among the major influencing factor that is contributing to this distress is the repeated heavy traffic loading on the road surfaces. [1,2]. Moreover, the use of waste crumb rubber in road construction as a pavement surface has a better skid resistance, fatigue crack resistance and increased rut resistance. The review includes physical tests that are used to determine the physical properties of bitumen and modified crumb rubber mix. The physical tests involve penetration test, softening point test and viscosity test. The second stage is rheological tests like rolling thin film oven test (RTFOT), pressure aging vessel (PAV) and dynamic shear rheometer (DSR) tests [3]. The expectations from the study are to develop bitumen with waste crumb rubber that would minimize the costs of bitumen and providing better physical and rheological properties compared to the convention bitumen based on the tests that was conducted. Crumb rubber modifier as improved resistance to rutting due to high viscosity, Improved resistance to surface initiated, reduce fatigue/ reflection
cracking, lower pavement maintenance costs, and saving in energy and natural
resource[4,5].
METHOD
In general there are two methods of blending waste crumb rubber with bitumen , which is the dry process and wet process. The wet process was first developed by Charles in 1981which the modification was carried out at 5 to 25% by mass of fine crumb rubber at high temperature. The wet process includes the mixture or blending of crumb rubber with bitumen at high temperatures and produces a viscous fluid through rubber bitumen interaction [4]. Figure 1 illustrates the application of crumb rubber in the wet process to produce premix for paving works. The performance of CRM mixtures using the wet process has been evaluated by different researchers under both field condition and laboratory testing. In terms of mechanical performance such as fatigue, the crumb rubber blended with bitumen using the wet process presents a better resistance to fatigue compared to conventional mixtures.
Figure 1 Application of crumb rubber in wet process for asphalt modification
It is usually added to the coating in a size of 9.5 mm or less. But in addition, it is divided into 4 groups according to the size of the rubber [6]
- 6.3-9.5 mm - large
- 1-2 mm medium
- 0.2-0.4 mm small
- 0.075-0.15 mm, very small
Regular rubber flakes - where the rubber is crushed at normal room temperature. Frozen rubber pieces - in this case, the rubber is mixed with a special nitrogen liquid and then crushed. But in this case, it will be somewhat difficult for the
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rubber pieces to react with the asphalt concrete. Below we will see the mutual characteristics of these two methods [7].
Parameter Ambient Cryogenic
Operating temperature Ambient, max. 120^ Below-80 °C
Size reduction principle Cutting tearing^ shearing Braking cryogenically embrittled rubber pieces
Particle morphology Spongy and rough, high specific surface Even and smooth, low specific surface
Particle size distribution Relatively narrow particle size distribution, only limited size reduction per grinding step Wide particle size distribution (ranging 10mm to 0.2mm) in just one processing step
Maintenance cost Higher Lower
Electricity consumption Higher Lower
L N 2 Consumpt io n N/A 0.5-1.0 kgLN2 per kg tire input
RESULTS AND DISCUSSION.
In the wet method, car tires are crushed in a special grinder, mixed with bitumen, heated, and then mixed with other aggregates. In this case, the main function of rubber is BINDING material. By the American Society for Testing and Materials (ASTM) as "A mixture of asphalt concrete, recycled tires and certain additives in which the rubber component is at least 15% by weight of the total mixture and reacts with them" defined [8]. In this method, asphalt is mixed with crushed rubber (rubber) in a modifier (CRM) mixing device for specialization at temperatures of 190 - 225 °C for at least 45 minutes. It helps the chemical bonding of components. This reaction is affected by mixing temperature, time of temperature rise, type and amount of mechanical mixing, size and structure of rubber, and aromatic component of asphalt. Rubber usually makes up 18 to 22% of asphalt by weight. It is also used as a spray and crack sealant for seal coats and pavement interlayers. The addition of crushed rubber particles (<1.0 mm size) to asphalt mixtures produced mixtures with improved properties in terms of stiffness, permanent deformation resistance, and crack resistance [9]. CONCLUSION
In the dry method, car tire rubber is mixed with bitumen after passing through a special grinder and directly mixed into aggregates. This method was specifically patented in Sweden and the USA in the 1960s [10]. Although this method is effective, it is not widely used. According to the conclusions of the research carried
out by Fernandes in 2002, asphalt concrete prepared by adding rubber in a dry way increases the elasticity of the pavement and extends the life of the pavement, reducing the effect of thermal temperature and external humidity [11]. The coating prepared by adding 2-8mm rubber pieces reduces the effect of external moisture and reduces its hardness.
Another study conducted by Kettab and Bali (2004) shows that the addition of rubber particles larger than 2 mm in the coating fills the gap between the coating skeletes. Also, adding rubber in the amount of 10-15% of the coating increases the temperature of the coating and increases its viscosity. According to research conducted in Brazil, adding 0.15-1.18 mm rubber at a ratio of 2% of the total coating reduces the cracking of the coating.
REFERENCES
1. Bahia, H.U., D. Perdomo, R. Schwartz, and B. Takallou. January. 1997.Use of Superpav Technology for Design and Construction of Rubberized Asphalt Mixtures. Presented at the 76th Meeting of the Transportation Research Board.
2. Bahia, Hussain and Robert Davies.1994. Effect of Crumb Rubber Modifiers (CRM) on Performance-Related Properties of Bitumens. Journal AAPT 1994. 414441.
3. Amirkhanian, S. and Corley, M. 2004. Utilization of Rubberized Asphalt in the United Statesan Overview. Proceedings of 04 International Symposium Advanced.
4. Takallou H. B., Takallou M. B.1991. Recycling Tires in Rubber Asphalt Paving Yields Cost, Disposal Benefits, Elastomerics. 123: 19-24.
5. Harvey, J., Bejarano, M., Popescu, L. 2000. Accelerated Pavement Testing of Rutting and Cracking Performance of Asphalt-Rubber and Conventional Asphalt Concrete Overlay Strategies. Conference on Asphalt Rubber, Vilamoura, Portugal.
6. Osman, S. and A. Adam, 2012. Evaluation of Crumb Tire Rubber-Modified Hot Mix Asphalt Concrete in Sudan. Sustainable Construction Materials: 235-248.
7. Othman, A. M, 2006. Fracture Resistance of Rubbermodified Asphaltic Mixtures Exposed to High-Temperature Cyclic Aging. Sage Publishers. Journal of Elastomers and Plastics. 38: 19-32 available at http://jep.sagepub.com.
8. Ibrahim M. R, Katman H. Y, Rehan M, Mahrez A. 2009. Properties of Rubberised Bitumen Mixes Prepared With Wet And Dry Mixing Process. Proc. Eastern Asia Soc. Transp. Stud. 7: 1-11.
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9. Liu S, Cao W, Fang J, Shang S. 2009. Variance Analysis And Performance Evaluation Of Different Crumb Rubber Modified (CRM) Asphalt. Constr. Build. Mater. 23: 2701- 2708
10. Katman H. Y, Karim M. R, Mahrez A, Ibrahim M. R, 2005a. Performance of Wet Mix Rubberized Porous Asphalt. Proc. Eastern Asia Soc. Transp. Stud. 5: 695-708.
11. Fernandes Souza and Weissman 2002. Using a Binder With 15% Rubber Content (Size Of 0.2,0.4 And 0.6mm). In DenseGraded Bitumen.
РЕСПУБЛИКАМИЗНИНГ ТАБИИЙ ЩЛИМ ШАРОИТИ ОМИЛЛАРИНИНГ ТЕМИР БЕТОН КОНСТРУКЦИЯЛАРИГА ТАЪСИРИ
проф. Ризаев Боходир
Наманган мухандислик-курилиш институти
Аннотация: Ушбу маколада Республикамизнинг курук иссик икдимли шароитларда курилган ва фойдаланилаётган бетонли ва темирбетон конструкцияларни холати тахлил килинган. Назарий ва экспериментам тадкикотлар оркали иклим шароитларини бетонли ва темирбетон конструкцияларга салбий таъсири урганиб чикилган.
Калит сузлар: Курук иссик иклим, иклим омиллари, ёриклар хосил булиш моменти, мустахкамлик, намлик, харорат, куёш радиацияси, бикрлик, куриб чукиш деформацияси, хароратли зурикиш.
Курук иссик иклимли шароитларда курилган ва фойдаланилаётган бетонли ва темирбетон конструкцияларнинг холати бир хилда эмаслиги кузатилган.
20 йил ва ундан купрок вакт ишлатилаётган ва коникарли холатларда булган иншоотлар билан бир каторда янги барпо килинган баъзи конструкциялар ремонт талаб килади ёки кайтадан тиклашни такозо килади.
Тошкент тукимачилик комбинати, Тошкент тукимачилик машинасозлиги комбинати, Голодностепстрой сугориш системаси иншоотлари текшириб курилганда купгина бетон ва темирбетон конструкцияларни емирилиб, бузилганлиги аникланган.
А.Ф.Милованов, А.В.Нифонтов, Э.А.Мазо [1] тадкикотларида курсатилишича хароратнинг юкори булиши, ёрикларни эрта хосил булишига сабаб булиб, эгилувчан темир-бетон элементларни бикрлигини камайтиради.
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