Experimental Study On Fatigue Self-Healing Properties Of Asphalt And Asphalt Mixture Under UV Aging

China’s the construction of highways has become more and more perfect.As a high-quality and mature pavement material,SBS modified asphalt has been widely used in China.When the asphalt pavement is affected by the vehicle load and the external environment for a long time,it will age,which will cause fatigue cracking of the asphalt pavement.The aging of asphalt is a complicated process.At present,the research on PAV at home and abroad is relatively mature,but the aging caused by UV aging is neglected,which also has a serious impact on the road surface.The study found that after the asphalt material wasdamaged,it had a certain self-healing ability undercertain conditions.Therefore,studying the self-healing ability of asphalt materials is of great significance for the design and use of asphalt pavement.This paper mainly considers the intensity of sunshine in the Inner Mongolia Plateau,and the asphalt pavement will undergo UV aging under long-term illumination.Through the high and low temperature test of asphalt and AFM microscopic observation test,analyzed the effect of UV aging on the performance of SBS modified asphalt;through DSR time scanning test,analyzed the fatigue damage and self-healing properties of SBS modified asphalt by UV aging The effect of UV aging on fatigue damage and self-healing properties of SBS modified asphalt mixture was analyzed by UTM for four-point bending fatigue test of asphalt mixture.The combination of macroscopic and microscopic methods can more effectively evaluate the impact of UV aging on SBS modified asphalt pavement,and give corresponding recommendations.The main conclusions are:The high temperature,low temperature and microscopic observations of SBS modified asphalt before and after UV aging were carried out by DSR temperature scanning,BBR creep test and AFM microscopic test.The results show that UV aging will increase the asphaltene content in asphalt sharply,the asphalt is changed from viscous to elastic,which improves the high temperature performance of the asphalt,but reduces the flow properties of the asphalt.The addition of water will further improve the high temperature performance of the asphalt material;however,UV aging has little effect on the low temperature performance of SBS modified asphalt in the early stage.As the aging degree deepens,the low temperature performance of asphalt decreases sharply.The addition of the asphalt material will restore the low temperature performance of the asphalt material within a certain range;in the microscopic field,as the aging degree deepens,the Young’s modulus of the asphalt surface increases,and the elastic properties of the asphalt surface are improved,the results obtained are consistent with the macroscopic experiments.The fatigue healing test of SBS modified asphalt before and after UV aging was carried out by DSR time scanning.The results show that aging can improve the fatigue resistance of asphalt to some extent from the modification of SBS and the self-healing compensation.The healing of asphalt is dependent on time and temperature.As the temperature increases and the time increases,the healing effect becomes better.Aging will reduce the healing ability of asphalt.Adding spray will cause water aging of asphalt and will continue to reduce asphalt healing performance.The healing ability,when the damage level reaches a large level,will greatly reduce the healing performance of the asphalt.The fatigue healing experiments of SBS modified asphalt mixture before and after UV aging were carried out by UTM.The results show that the three fatigue indexes of N_f50,N_fNMNM and cumulative dissipative energy can be used to obtain the consistency law,that is,as the degree of aging deepens,the fatigue life of the asphalt mixture gradually decreases;although the asphalt mixture will have a certain self-healing recovery in a short period of time,from the perspective of dissipative energy,the internal strength has not been well restored.