Damage Characteristics Of SBS Modified Asphalt Material Under Coupling Action Of Salt Freeze-thaw Cycle And Ultraviolet Radiation

In northern China,the long winter season and low temperatures lead to snow and ice accumulation on pavement surfaces,posing a threat to traffic safety.To ensure safe driving,snow melting agents are commonly used to melt snow and ice on the road.However,while snow melting salt can effectively melt snow and ice,it also causes significant damage to asphalt pavement surfaces.When snow melting salt is spread on the pavement surface,it melts snow and ice,and seeps into the asphalt pavement in the form of a solution.During the alternating freeze-thaw cycle of winter and intense UV radiation,the pavement surface may develop ruts,cracks,and other defects,causing damage to the asphalt pavement structure.This paper simulated the actual pavement surface usage environment in Urumqi,Xinjiang,based on local climatic and environmental conditions and engineering practices.The salt freeze-thaw cycle and UV aging test schemes were designed to investigate the salt corrosion damage characteristics of SBS-modified asphalt pavement caused by two commonly used chloride salt-type snow melting agents,sodium chloride and calcium chloride.Fourier transform infrared spectroscopy and scanning electron microscopy were used to analyze the damage mechanism of the asphalt binder during the salt freeze-thaw cycle and UV aging process.Three major indicators,dynamic shear rheology,and bending beam rheology were used to test the changes in the conventional road performance and rheological properties of the asphalt binder after the salt freeze-thaw cycle and UV aging.High-temperature rutting,low-temperature bending beam,freeze-thaw splitting,and crack extension tests were used to evaluate the road performance of the asphalt mixture after salt freeze-thaw cycle and UV aging.The research findings indicate that:（1）After salt salt freeze-thaw cycle and UV aging,asphalt underwent water aging,and some SBS modifiers degraded.Salt intrusion into asphalt lead to an increase in the content of asphaltene and resinous materials,and destroyed the three-dimensional network structure of SBS modifiers in asphalt.The degree of asphalt erosion by Na Cl snow melting agent was greater than that of Ca Cl₂snow melting agent.（2）The addition of snow melting agent reduced the penetration value of asphalt,increased the softening point,and decreased the ductility,resulting in more obvious elastic properties of asphalt.With the increase of snow melting agent concentration and the time of salt freeze-thaw cycle sand UV aging,the high-temperature resistance to deformation of asphalt became better,but the low-temperature extensibility became worse.The effect of Na Cl snow melting agent on the high and low-temperature performance of asphalt was more significant than that of Ca Cl₂snow melting agent.（3）After salt freeze-thaw cycle and UV aging,the high-temperature resistance to rutting of asphalt was improved,the fatigue resistance was reduced,and the temperature sensitivity was decreased,and the changes became more significant with the increase of salt freeze-thaw and UV aging cycles.The high-temperature resistance to rutting of asphalt under the action of Na Cl snow melting agent became better,but the fatigue resistance became worse.The effect of solution composition on the high-temperature rheological properties of asphalt decreased with increasing temperature.（4）The addition of snow melting agent degraded the low temperature creep and crack resistance of asphalt.With the increase of aging time,the low-temperature creep and crack performance of asphalt deteriorated.（5）The performance indicators of asphalt mixture for various road used all deteriorate under the action of snow melting agents,and the deterioration effect of Na Cl snow melting agent on asphalt mixture was more significant than that of CaCl₂.