Research On The Change Law Of Asphalt-aggregate Interfacial Bond Strength Under The Influence Of Salt Immersion And Freeze-thaw Cycles

Asphalt pavement is the most widely used in modern roads.In cold regions,snow melting agents are often sprayed to eliminate road rain and snow.After the snow and ice melt,a large amount of chlorides diffuse into the asphalt pavement,and the hot and cold alternately circulate,causing the mechanical properties of the asphalt-aggregate.Great influence has caused the phenomenon of surface granulation of asphalt pavement,loose flaking of aggregates,cracking,etc.Many scholars have shown that the bonding interface between asphalt and aggregate is the weak link of asphalt pavement structure and various forms of damage.Often originated from the destruction of the interface,the mechanical properties between the interfaces determine the key to the use of asphalt pavement.In order to study the mechanical properties of the interface between asphalt and aggregate,a self-designed drawing experimental device was used,together with an electronic universal testing machine and an environmental chamber,the aggregate-asphalt-aggregate bonded test piece was first prepared,and according to the orthogonal experiment.The prepared test piece is subjected to salt liquid freeze-thaw cycle,the mass of the test piece after each freeze-thaw cycle is measured,the percentage of water absorption is determined,and the water absorption rate is analyzed by the range method,the salt concentration,the number of freeze-thaw cycles,and the water immersion The extent of the impact of time.Secondly,the tensile test is carried out to obtain the stress-deformation curve of each test piece under the load.The observation and analysis of the tensile failure interface are carried out.The range analysis method is used to deeply investigate the salt concentration and freeze-thaw of the chloride salt snow melting agent at different temperatures.The effects of cycle number and water immersion time on the mechanical properties of asphalt-aggregate bonding interface and their correlation were analyzed,and the fracture energy generated by interface failure was calculated.The results show that the bond strength of asphalt-aggregate interface decreases under salt freezing and water immersion,and the asphalt-aggregate bond strength is sensitive to temperature.The damage form of asphalt and aggregate includes adhesion failure between asphalt and aggregate.The cohesive failure of the asphalt film itself;under the combined effects of salt concentration,number of freeze-thaw cycles and water immersion time,the concentration of chloride salt snow melting agent has the most significant influence on the water absorption of the asphalt-aggregate bonded test piece.The number of freeze-thaw cycles has the most significant influence on the asphalt-aggregate interface failure deformation;the fracture energy generated by the asphalt-aggregate interface failure at low temperature and normal temperature is large,and the fracture energy at high temperature is small.