Study On The Effect Of Sodium Erosion On Asphalt Self-healing And Fatigue Performance

In recent years,scholars have carried out a lot of research on the durability of asphalt mixture under the salt erosion environments,and achieved rich results.However,very few studies have focused on the influences of salt erosion on the performances of asphalt.As the binder of asphalt pavement,the performance of asphalt directly affects the quality of asphalt pavement.Therefore,it is of great engineering value and practical significance to study the performance of asphalt under salt-erosion environment.In the present paper,the method of vibration immersion erosion is designed to simulate the sodium salt erosion of asphalt.The influence of three kinds of sodium salts on the microstructure of asphalt is studied by four-component,FT-IR and SEM.Based on the improved dynamic shear rheological（DSR）tests and pull-out test,the basic performance,rheological performance,self-healing ability and fatigue performance of asphalt in different sodia-salt erosive environments are studied.And the correlation between the performance of asphalt is analyzed.The significance ranking of different influencing factors（salt solution concentration,erosion time,and temperature）is determined by the F-test.The present work can serve as a reference for the durability study of asphalt pavements in salt erosion environments.The results of microscopic characteristics show that there are some physical and chemical changes in asphalt under salt-erosion environment,which show that the colloidal balance of asphalt is broken,some groups of asphalt interact with sodium solution,and the microscopic morphology of bitumen changes.The performance results reveal that Na₂SO₄ has the most significant influence on asphalt performance,followed by CH₃COONa and the smallest Na Cl.And the worse the salting environment is,the more obvious the change of asphalt performance is.Under the action of sodium salt erosion,the consistency and hardness of asphalt increase,which show that the total anti-deformation ability,anti-rutting ability and creep recovery ability of asphalt increased.However,the low temperature ductility,self-healing ability and performance property of asphalt are severely weakened.The relative increase of asphaltene content is the main reason for the increase of creep and rutting resistance of asphalt and the decrease of self-healing ability.The decline of asphalt stability,the change of asphalt surface morphology and the formation of defects in asphalt caused by sodium salt are the main inducements to reduce the fatigue performance,which explains the frequent fatigue cracking of asphalt pavement under salt erosion environment from the perspective of asphalt.The results of correlation analysis reveal that there is a close correlation between the performance indexes of asphalt under salt erosion environment,and the relationship between asphalt performance indexes can be better described by nonlinear model.The F-test results show that the influence of corrosion temperature on asphalt self-healing ability and fatigue performance is much greater than that of salt solution concentration and erosion time.It can be inferred that the negative effect of sodium salt erosion on the performance of asphalt mainly occurs in late spring or early summer when a lot of salts still remain on pavements and the weather is relatively warm and humid.