| With the development of China’s economy,the demand for transportation is increasing.As of 2019,the mileage of highways in China has exceeded 140,000 kilometers,which is mainly composed of asphalt roads.Due to the high traffic volume in our country and the phenomenon of overloaded vehicles,the asphalt pavement has suffered serious diseases before reaching its designed service life.Common diseases include loosening,spalling,rutting and cracking.The polymer modifier can produce chemical and physical cross-linking with asphalt,can effectively improve the performance of asphalt,and is widely used in the construction of asphalt pavement.This paper uses SBS,SBR and SK70 # matrix asphalt as raw materials to design different modified asphalt preparation conditions.The effects of shear time and material development and shear process on the conventional performance of asphalt are studied.The results show that: When mixing and shearing for 1.5h and 1h,various performance indexes of asphalt can be significantly improved;adjusting the order of addition of SBS and SBR has no significant effect on the conventional performance of modified asphalt.Pre-shear SBS and asphalt before adding SBR can improve the storage stability of modified asphalt.Based on the four modifiers of SBS,SBR,sulfur and furfural extraction oil,composite modified asphalt was prepared and tested for three major indexes,viscosity and storage stability of asphalt.The results show that SBS and sulfur have a significant effect on the penetration and softening point of asphalt.Increasing the content of SBS and SBR can improve the low-temperature crack resistance of asphalt.Orthogonal test range analysis determined that the blending scheme of SBS-SBR composite modified asphalt was SBS content of 7% and SBR content of 4%.Using furfural extracted oil with higher saturation content and aromatic content can improve the storage stability of SBS-SBR composite modified asphalt.The softening point difference of composite modified asphalt prepared by adding 3% mass fraction of furfural extracted oil is 2.3 ℃.Based on the conventional performance test and storage stability test,the material composition of SBS-SBR composite modified asphalt is determined to be asphalt: SBS:SBR: sulfur: furfural extracted oil = 100: 7: 4: 0.2: 3.The performance of composite modified asphalt and asphalt mixture was tested.The results show that the asphalt prepared by SBS-SBR composite modification has good high-temperature and low-temperature performance,which can meet the requirements of the conventional performance of modified asphalt in China.The dynamic shear rheological test(DSR)results show that: SBS and SBR can effectively improve the modulus and elastic recovery ability of asphalt.The composite modification process is used to increase the ultimate rutting resistance temperature of the matrix asphalt by 17 ℃,effectively improving the asphalt The deformation resistance and high temperature stability of asphalt mixture.The low-temperature beam creep test(BBR)results show that the low-temperature creep stiffness modulus of the four asphalts is sorted from large to small as matrix asphalt> SBR modified asphalt>SBS modified asphalt> composite modified asphalt,modified asphalt The value of m is greater than the base asphalt,and the modifier improves the asphalt’s low-temperature stress relaxation ability.The critical temperature Tc of asphalt was calculated,and the results showed that the critical temperature of asphalt prepared by composite modification was-19.8 ℃,which was lower than that of SBS modified asphalt and SBR modified asphalt.The AC-13 grade was used for the mix ratio design to test the road performance of the SBS-SBR composite modified asphalt mixture.The results show that the high temperature performance,low temperature performance and water stability of the composite modified asphalt mixture are relative to the matrix asphalt has been greatly improved. |
