Low Temperature Crack Resistance Of Large Dose Rubber/Polyester Fiber SMA Asphalt Mixes

With the continuous development of asphalt concrete technology in recent years,asphalt pavement has become the main form of pavement in high-grade highways.However,in the cold regions of northern my country,due to factors such as the large temperature difference between day and night and the long duration of rain and snow,the problem of asphalt pavement cracking has become more and more serious.A new type of asphalt pavement with excellent low temperature crack resistance needs to be developed urgently.As one of the main wastes in the modern automobile industry,waste tires contain many components that can effectively improve the low temperature performance of asphalt mixtures.In this case,the application of a large amount of waste tyre rubber powder to asphalt pavement through a reasonable process not only solves the problem of pollution from waste tyre accumulation,but also reduces the cost of pavement while improving the performance of asphalt pavement,which has great economic value and positive social significance.In the test,7 kinds of rubber powders(0%,1.5%,2%,2.5%,3%,3.5%,4%)and rubber powder with 20% content(accounting for the total amount of rubber powder and rubber fiber)were selected.As the asphalt modification material and flexible aggregate,polyester fibers with 6 dosages(0%,0.3%,0.35%,0.4%,0.45%,0.5%)were selected as the toughening materials for anchoring and reinforcement.large-dosage rubber/polyester fiber(SMA-13)asphalt mixture was prepared by dry process(the amount of rubber powder in ordinary rubber-asphalt mixture is usually about 1%).Carry out pre-notch SCB tests at 4 test temperatures(0℃,-10℃,-20℃,-30℃),and comprehensively evaluate rubber/polyester fiber asphalt mixtures using three indicators of fracture toughness,fracture stiffness and fracture energy The low-temperature cracking resistance of the samples was obtained;the factor significance analysis of the peak load of the specimen was carried out by SPSS software;the modification mechanism of the material was explored by ultrasonic nondestructive testing technology and SEM technology.The main conclusions are as follows:(1)The test replaces the limestone aggregate with a particle size of less than 0.6mm with rubber powder by the "equal volume replacement method".After obtaining the optimized gradation,the Marshall test is used to determine the content of rubber powder and polyester fiber.The effect of the amount on the optimal asphalt dosage.(2)The SCB test results show that the optimum dosage of rubber powder is 3%,and the optimum dosage of polyester fiber is 0.4%,with the decrease of the test temperature,the fracture toughness of the SCB specimen increases first and then decreases.The fracture stiffness and fracture energy show a continuous decreasing trend.When the test temperature is-10 °C,the asphalt mixture exhibits the best low temperature crack resistance.(3)Through factor significance analysis,it is found that the content of rubber powder,polyester fiber and test temperature will have a significant impact on the peak load of SCB specimens when they act alone,and the influence of rubber powder content is the most significant.,followed by the test temperature,the polyester fiber content has the smallest effect,and when the three interact,the effect on the peak load of the specimen is not significant.(4)SEM scanning electron microscope results show that the polyester fibers with a dosage of 0.4% crisscross and overlap each other in the asphalt mixture,forming a uniformly distributed fiber space network,which provides a good wetting interface for the asphalt.The rubber powder with a content of 3%,while modifying the asphalt,acts as a flexible aggregate and is wrapped and nested with the network structure of limestone aggregate,mineral powder,asphalt and polyester fiber,forming a smooth interface transition and a continuous structure.The clear framework system ensures the uniformity of load transfer between particles.(5)Based on the SEM results,the mechanism of the interfacial energy interaction between asphalt,rubber powder and limestone was analyzed,and it was found that the addition of rubber powder enhanced the interfacial adhesion and interfacial phase strength of the mixture in many ways,has a positive impact on improving the durability and crack resistance of large-volume rubber/polyester fiber asphalt mixtures.Figure [25] Table [17] Reference [99]...