盐冻循环作用下沥青混合料损伤特性OA

To explore the fatigue performance and the evolution law of damage in the micro-fine voids structure of asphalt mixtures under the coupled action of salt freeze-thaw cycles,this paper conducted immersion salt solution Hamburg rutting tests and four-point bending tests on asphalt mixtures after salt freeze-thaw cycles,and it also studied the rutting resistance and fatigue performance degradation laws of asphalt mixtures after salt freeze-thaw damage.Based on industrial CT nondestructive testing technology,this paper analyzed the damage characteristics of the micro-fine voids structure in asphalt mixtures under the erosion of salt freeze-thaw cycles.The results show that:the erosion of salt freeze-thaw cycles significantly reduces the stability of asphalt mixtures under the coupled action of salt solution,temperature,and load.With the increase in the number of salt freeze-thaw cycles,the fatigue life and dissipated energy of asphalt mixtures decrease exponentially.Under the combined damage action of salt erosion,crystallization expansion,and freezing expansion,the volume of micro-nano-scale closed voids and semi-connected voids in asphalt mixtures increases,with closed voids developing toward semi-connected voids and semi-connected voids toward connected voids.The expected value of micro-fine voids diameter and the number of voids increase and decrease exponentially with the increase in the number of salt freeze-thaw cycles.The erosion of salt freeze-thaw cycles leads to an increase in the voids rate of asphalt mixtures,which is the main reason for the generation of compaction-type rutting and the rapid degradation of fatigue performance in asphalt pavement.