Study On Ultraviolet Aging Performance Of Composite Modified Asphalt In Eastern Inner Mongolia

In order to achieve rural rejuvenation,the Ministry of Communications promotes the"Four Good Rural Roads" policy.Due to its unique natural pastures and fertile land,the eastern region of Inner Mongolia occupies a large proportion in the eastern region.In order to implement the spirit of the policy and ensure the economic development of agricultural and pastoral areas,the existing rural roads need to be upgraded.Because of its many advantages,asphalt pavement is currently the main method adopted in the reconstruction and expansion of rural roads.The eastern region of Inner Mongolia is located on the Mongolian plateau,with high altitude and long sunshine time,and its ultraviolet radiation is much larger than other plains.As a typical organic gel material,asphalt is prone to aging after ultraviolet radiation,which causes many diseases and reduces the service life of the pavement.Therefore,find an anti-ultraviolet aging asphalt suitable for eastern Inner Mongolia and explore its ultraviolet aging mechanism Vital.Based on the three kinds of compound modified asphalts developed by the team in the early stage,the following research was carried out:(1)By investigating the amount of ultraviolet radiation in the eastern part of Inner Mongolia and combining the ultraviolet aging weather resistance test chamber,a conversion relationship between indoor and outdoor ultraviolet aging time was established.(2)The physical properties and chemical composition of the composite modified asphalt under three different aging times were tested.Ultraviolet aging has improved the high-temperature performance of asphalt,increasing the softening point and viscosity,and reducing penetration,but lowering the low-temperature performance of asphalt,reducing ductility,and increasing brittleness.The change of chemical composition is the main reason for the change of high and low temperature performance of asphalt.The saturated content,aromatic content and gum of asphalt are reduced,the asphaltene is increased,the asphalt is hardened,and the asphalt is transformed from sol structure to gel structure.(3)The rheological properties of three kinds of composite modified asphalt under different aging time were tested.UV aging increases the rut resistance of asphalt,but has a negative impact on low temperature crack resistance and stress relaxation ability.By comparing and analyzing the physical properties and rheological properties of the asphalt before and after aging,it was found that No.2 asphalt has the strongest UV aging resistance among the three types of asphalt.(4)Based on the materials studio software,a four-component molecular model of asphalt before and after aging was constructed,and four molecular models of matrix asphalt and modified asphalt No.2 before and after aging were constructed according to the four-component ratio of the aforementioned asphalt.Through dynamic simulation of the molecular model,it is found that the density of the asphalt does not change much regardless of aging and modification,but it will increase its system energy.After aging,the cohesive energy density of.the asphalt increases,and the intermolecular interaction becomes stronger.The increase amount of the bitumen is less than that of the matrix asphalt.Aging will reduce the compatibility of the matrix asphalt and the modifier,thereby reducing the asphalt performance,reducing the diffusion coefficient of the asphalt,and reducing its fluidity.From the perspective of the mechanical properties of the model,Aging and modification will increase the elastic modulus,bulk modulus,and shear modulus of the asphalt,thereby making the asphalt more resistant to deformation.