Study On The Performance Of Nano-Al₂O₃ Composite Modified Asphalt

As an important material for the construction of asphalt pavement,asphalt plays an essential role in the performance of asphalt pavement.Asphalt modification is an effective way to improve asphalt performance.As one of the most widely used modifiers,SBS modifier can significantly improve the performance of asphalt,but its performance still needs to be improved.Compared with traditional solid materials,nanomaterials boast small size and higher specific surface area.Given their ability to modify the matrix material,nanomaterials witness increasing application in the field of road materials.For example,nano-Al2O3,a typical metal oxide nanomaterial,which is often used as reinforcement and toughening of plastics,and has good high temperature tolerance and chemical stability,has been used as a modifier in asphalt modification research by some scholars in recent years.At present,the modification research of nano-Al2O3 on asphalt is mainly reflected in high temperature performance and fatigue resistance,but systemic research on its road performance has not been formed.In this paper,nano-Al2O3 was used to modify the base asphalt and SBS asphalt to prepare nano-Al2O3 modified asphalt and nano-Al2O3/SBS composite modified asphalt.The modification mechanism and anti-aging mechanism of nano-Al2O3 modified asphalt and nano-Al2O3/SBS composite modified asphalt were explored from multiple angles by microscopic test methods.First,nano-Al2O3 modified asphalt and nano-Al2O3/SBS composite modified asphalt with different contents were prepared.The effects of nano-Al2O3 on the performance of base asphalt and SBS asphalt were explored by basic physical property test（three major indexes test and viscosity test）,including temperature sweep test,multiple stress creep recovery test,low temperature bending beam rheological test,bond strength test and rotating film heating test.The results show that the high-temperature performance,bonding performance and anti-aging performance of the nano-Al2O3 modified asphalt prepared in this study are significantly improved compared with the base asphalt,and the low-temperature performance are slightly reduced;Compared with SBS asphalt,the high temperature performance,bonding performance and anti-aging performance of nano-Al2O3/SBS composite modified asphalt are significantly improved,and there is no negative impact on its low temperature performance.The improvement effect of nano-Al2O3 on the performance of SBS asphalt is significantly higher than that on the performance of base asphalt.Secondly,the modification mechanism and anti-aging mechanism of nano-Al2O3 on base asphalt and SBS asphalt were explored through the application of Fourier transform infrared spectroscopy test and Gel permeation chromatography test.The results demonstrate that the modification process of the base asphalt and SBS asphalt by nano-Al2O3 is physical blending.In the aging process of base asphalt,nano-Al2O3 can inhibit the growth of sulfoxide groups;in the aging process of SBS asphalt,nano-Al2O3 can inhibit the growth of sulfoxide groups in the asphalt system and prevent the cracking of polymers.Moreover,nano-Al2O3 not only can increase the molecular weight and content of macromolecular micelles in the base asphalt,but also can inhibit the conversion trend of small-molecular micelles in asphalt to macromolecular micelles under aging conditions;The modification effect of nano-Al2O3 on SBS asphalt increases the molecular weight and content of macromolecular micelles in the asphalt system.Under aging conditions,nano-Al2O3 plays an effective role in inhibiting the conversion of small molecular micelles to macromolecular micelles in the asphalt system and preventing polymer cleavage.On the basis of Fourier transform infrared spectroscopy and Gel permeation chromatography experiments,this study attempts to use atomic force microscopy experiments so as to deeply explore the microscopic mechanism of SBS asphalt with more complex composition and mechanism.The results prove that the number and volume of "bee structure" in SBS asphalt increased significantly under the effect of nano-Al2O3.In addition,Nano-Al2O3 can mitigate the drastic changes of the morphology of SBS asphalt,which is represented by "bee structure" under aging conditions.Finally,the correlation between functional group index and high temperature rheological index,and the correlation between functional group index and aging index in nano-Al2O3 modified asphalt and nano-Al2O3/SBS composite modified asphalt were respectively explored.It is proved that the correlation between high temperature rheological index and sulfoxide index SI is weak,and the correlation between dynamic shear modulus aging index CAI and ΔSI is the best.In nano-Al2O3/SBS composite modified asphalt,the correlation between the phase angle and the sulfoxide group index SI is the best,Moreover,PAI,the phase angle aging index,represents the best correlation between the aging index and ΔSI and the correlation the rutting factor aging index RPAI and R-I_B/S is the best.The comprehensive performance of the nano-Al2O3 modified asphalt prepared in this study and the nano-Al2O3/SBS composite modified asphalt are significantly improved compared with the unmodified original asphalt,which can be used in the construction of asphalt pavement.Road works have a positive meaning.