| With the development of the auto industry, the amount of cars has increased, so the accumulation of waste tires leading to "black pollution" has brought serious harm to the world. In recent years, a lot of countries pay more and more attentions to the problem of discarded tires, especially the National Development and Reform Commission made it clear to discarded tires recycling project as one of six key projects at《"11th Five-Year Plan" comprehensive utilization of resources and guidance》in 2007, according to the "11th Five-Year Plan".At present, there are many ways in recycling of discarded tires, for instance, prototype restructuring, the use of thermal energy, thermal decomposition, renovation of the tire, production of renewable plastic and for the civil engineering construction. The waste rubber in road engineering has become the best choice to deal with a large number of discarded tires in many countries. Foreign-related research results show that adding a certain amount of rubber powder can effectively improve the performance of asphalt, and increase the temperature of asphalt pavement rutting resistance, anti-low-temperature cracks, anti-fatigue, anti-aging, anti-slippery ability to extend the service life of the road, reduce road noise and improve traffic safety at the same time.As a binder in asphalt, the pavement of the road with comfort, low noise, easy to maintain and other characteristics, has become the major types of roads in many countries, and also in China. However, the track in overloading, under heavy load conditions or pavement cracks in bad weather, geological structure as well as unreasonable conditions show ordinary asphalt pavement has not adequately meet the requirements of the use of roads. As a result, take appropriate measures to improve the performance of asphalt, has become a long-term direction in the road workers.In recent years, polymer modified is widely used in our country from nothing to being. At present, the domestic polymer modified asphalt blends based on a simple modification of the main, most of the research is limited to the physical properties of polymer modified asphalt changes. Study on the compound modified asphalt becomes a new trend in foreign countries, and there are many successful examples that in the polymer modified asphalt at highway and bridge construction projects. However, the study on the waste rubber powder/SBS modified asphalt has not been seen the relevant reports yet.In this paper, based on the research project of Department of Jilin Province on the "Application Research on the Rubber Powder Modified Asphalt", the main research contend include:(1)Select the appropriate processes, and prepare the rubber powder / SBS (YH 791) composite modified asphalt; by testing the modified asphalt penetration, softening point, ductility and flexibility, verify the service performance of the rubber powder/SBS modified asphalt compound has met the basic requirement of SBS thermoplastic rubber-like polymer modified asphalt-IA and-IB standard in China's "Highway Modified Asphalt Pavement Construction Specifications", which suggest rubber powder / SBS modified asphalt is workable and provide a new train of thought for the modified asphalt.(2)The test results of mechanical properties of the blend sample including rubber Powder/SBS show that the mechanical properties of the mixture decrease. During the process to crash the discarded tires in mechanical shear method, the number of molecular chain decrease which reduce the average molecular weight of rubber, so that the struggle among molecular chain decreases, the degree of freedom increases, the ability to bear the ultimate stress declines, bond strength become weak and the stress relaxation increases. In addition, under the influence of the mechanical shear stress, cross-linked network of rubber Powder is damaged, which lead to a decline in mechanical properties.(3)The test results of mechanical properties of the blend sample including rubber Powder/SBS show that the mechanical properties of the mixture decrease. During the process to crash the discarded tires in mechanical shear method, the number of molecular chain decrease which reduce the average molecular weight of rubber, so that the struggle among molecular chain decreases, the degree of freedom increases, the ability to bear the ultimate stress declines, bond strength become weak and the stress relaxation increases. In addition, under the influence of the mechanical shear stress, cross-linked network of rubber Powder is damaged, which lead to a decline in mechanical properties.(4)The swelling experiments of rubber powder/SBS in the matrix asphalt show that with the increase of swelling time, the swelling rate increases; when the temperature rises, the swelling rate obviously increases. As the temperature increases, the asphalt element speed up the movement, at the same time, the activity of polymers rises. The speed of asphalt element permeating into the gap of polymer chain rises, which enhances the swelling rate. Polymer has the modification owing to its swelling. After polymer mixes with asphalt, polymer swells under the influence of the light components showing nature of the interface which is different from polymer and asphalt. The swelling of polymer is the premises of its good compatibility, which make the polymer combine with asphalt, so that the polymer evenly distributed in the asphalt. Swelling performance of the polymer show that oil separates out of asphalt , adheres to the interface of polymer and infiltrates into polymer to make it swell. Finally, the oil forms a colloidal structure similar to asphalt, which modifies the performance of the asphalt.(5)From the root of generating the tire/road noise, the theory to decrease noise by reducing vibration and absorbing noise is analysised, design the test program of absorption coefficient of rubber powder/SBS compound modified asphalt based on orthogonal layout, make Marshall sample in the Jilin institute of Traffic Science. At the same time, this paper conduct the test on absorption coefficients of Marshall sample using measurement system of impedance tube acoustic materials in the noise laboratory of Automotive college of Jilin University, then conduct range analysis and variance analysis based on the test date of coefficients of sound absorption. At last, this paper get the final selection of rubber content 5wt%, SBS content 3wt%, aromatic oil content 7wt% as the best formula to produce rubber powder/SBS compound modified asphalt.(6)Based on the research on the coefficient of sound absorption of rubber powder/SBS compound modified bitumen, lay the test road in accordance with the best formula, then conduct noise comparison test between the roads with rubber powder/SBS compound modified asphalt and SBS modified asphalt using fixed-point method and on-board method. From the test data, we can see that with the increase in speed, the effect of absorbing noise of the road with rubber powder/SBS modified asphalt become more and more obvious and reduce an average of about 1.5 dB noise, the largest mount of 2.5dB noise. Through the analysis of the test data, this paper conclude that the road with rubber powder/SBS compound modified asphalt and SBS modified asphalt have the same ability to reduce noise, which provide a new approach to reduce road traffic noise. |
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