Study On Technical Performances And Modification Mechanism Of Tourmaline Powders Modified Asphalt

In this paper,the inorganic material tourmaline was added to the matrix asphalt,and the tourmaline powders modified asphalt with 15%,18%and 21%total content was prepared.The routine performance test,dynamic shear rheological test(DSR),bending beam rheometer test(BBR),rolling film aging test(RTFOT),pressure aging test(PA’V)and direct baking combustion test were carried out to study the macroscopic properties of tourmaline powders modified asphalt.The modification mechanism of tourmaline powders modified asphalt was further explored by microscopic test,infrared spectroscopy and scanning electron microscopy.The results show that:(1)The addition of tourmaline powders can reduce the penetration and increase the softening point,and the high temperature performance of asphalt is improved;the low temperature ductility of tourmaline powders modified asphalt decreases and the worst ductility value is only 44%of the matrix asphalt;the storage stability decreases with the increase of tourmaline content.(2)The temperature sweep in DSR shows that the complex shear modulus and the rutting factor of the modified asphalt increase,thus tourmaline modifier can strengthen the asphalt’s ability to resist rutting defonnation under high temperature conditions,and the phase angle becomes smaller,which proves that the elastic component of the viscoelastic material tourmaline powders modified asphalt is increased;the frequency sweep results show that the composite viscosity and the zero shear viscosity value of tourmaline powders modified asphalt increase within the test frequency range,therefore the anti-deformation ability of asphalt is improved;the bending beam rheometer test shows that tourmaline improves the creep stiffness of the asphalt and reduces the creep rate,and the stress relaxation capability of the asphalt is weakened.(3)After aging the high temperature stability of tourmaline powders modified asphalt is improved,while the low temperature crack resistance is weakened to some extent;the PG grade of the modified asphalt is PG70-22,and the high temperature PG grade of modified asphalt is one grade higher than that of matrix asphalt,and the low temperature PG grade is unchanged.(4)The addition of tourmaline can increase the asphalt ignition point by 18.3℃,which is beneficial to delay the asphalt burning process.The emission of toxic and harmful gases such as CO,NO,CO2 and SO2 is reduced during the combustion of tourmaline powders modified asphalt,so it has good environmental performance.Considering social benefits and economic costs,the application prospect of tourmaline powders modified asphalt is quite broad.(5)The tourmaline modifier can be well dispersed in the matrix asphalt when the content is 15%and 18%;in the aging process of the tourmaline powders modified asphalt,the oxygen-containing functional group formed inside the asphalt,and carbonyl index and sulfoxide-based index are increased,so the anti-aging properties of modified asphalt are affected.