Study On Properties And Mechanism Of Blended Rubber Powder Modified Asphalt

Ordinary rubber powder used for asphalt modification has good high temperature performance and fatigue resistance,however,it also showcases some clear shortcomings,such as high viscosity,poor storage stability and so on.Desulfurized rubber powder has not been widely used because of the high cost of desulfurization and the complexity of the process.Taking into consideration the flaws of the two kinds of rubber powder modified asphalt,and the environmental problems caused by waste tires,this paper focuses on blending desulfurized rubber powder with ordinary rubber powder for asphalt modification,and studies the properties of the resulting rubber powder modified asphalt and its mixture after blending.Firstly,considering the influence of the content of the two kinds of rubber powder on the performance of base asphalt,they were selected to modify asphalt,and the initial content after blending rubber powder was determined to be 20%.Through the orthogonal test of four factors and three levels,the preparation process parameters were determined as follows:development time 2h,shear speed 5000r/min,shear time 50min,and the content of desulfurized rubber powder in blended rubber powder modified asphalt was set at 75%.The influence of the total content of blended rubber powder on the performance of modified asphalt was then analyzed.On this basis,the content of blended rubber powder was determined to be 28%,and the blended rubber powder modified asphalt prepared with this content had a good performance.Secondly,via the scanning electron microscope test,infrared spectrum test,differential scanning calorimetry(DSC)and comprehensive synchronous thermal analysis(TGA)test,the modification mechanism of asphalt modified by blended rubber powder was explored.The analysis results show that the molecular weight of rubber powder after desulfurization was reduced,the surface activity was enhanced,and there was chemical reaction with asphalt.Adding desulfurized rubber powder into rubber asphalt helped increase the content of rubber powder in asphalt,as well as improve the low temperature performance of rubber asphalt and reduce the viscosity.Lastly,AC-16 gradation was selected to study the road performance of rubber powder modified asphalt mixture,and the best asphalt-aggregate ratio of rubber powder modified asphalt and rubber asphalt was determined by Marshall test.The road performance test of rubber powder modified asphalt mixture was carried out,and its performance indexes could meet the requirements of current specifications.