Study On The Properties Of Desulfurized Rubber Powder/SBS Composite Modified Asphalt And The Performance Of Its Mixture

Rubber asphalt has poor storage stability and large construction smoke,which seriously affects its further promotion and use;SBS modified asphalt is widely used,but it has limitations such as easy aging and high cost.In order to solve this difficult and painful problem,combined with rubber powder desulfurization and rubber powder/SBS compounding measures,desulfurized rubber powder and SBS were adopted for the purpose of asphalt modification,and the performance of desulfurized rubber powder/SBS composite modified asphalt and its mixture was tested and analyzed.The main research contents were as follows:(1)Combining penetration,ductility,softening point,and viscosity other indicators,these tests were combined to determine the preparation parameters of the desulfurized rubber powder/SBS composite modified asphalt as follows:desulfurized rubber crumb content of 25%,SBS content of 2%,the method of adding SBS for shearing and then adding desulfurized rubber powder,preparation temperature of 175℃,and shear time of about 50min.The basic performance,viscosity-temperature characteristics,anti-aging performance,storage stability,rheological properties and smoke emission of composite modified asphalt were compared and studied.The results showed that it had excellent viscosity-temperature characteristics,antiaging durability and rheological properties.The storage stability was further improved,the SO2 emission was reduced by about 25%compared with the SBS modified asphalt,and the NO2 and NOx emissions were reduced by more than 50%.(2)Comparative analysis results of the microscopic morphology and chemical distribution of functional groups of the composite modified asphalt,combined with the analysis of the surface morphology of the rubber powder and clarified its modification mechanism.In the composite modified asphalt,the desulfurization rubber powder and SBS modifier were uniformly dispersed and cross-linked with each other.The interface between the desulfurization rubber powder-SBS-asphalt was blurred,sol-gel changes occur,chemical bond changed and grafting reactions existed,and a more stable three-dimensional network structure was formed.The modification process was a compatible and stable modification in which physical blending and chemical reaction coexist.(3)The road performance of the composite modified asphalt AC-13 and SMA-13 graded mixture was verified.The results showed that the composite modified asphalt met the current specifications,had excellent high-temperature rutting resistance,and was more prominent in the discontinuous gradation.The low-temperature crack resistance was slightly lower than that of the SBS modified asphalt,and the water stability was equivalent to that of the SBS modified asphalt,both reaching more than 90%.