Study Of The Shear Mechanical Behavior Of The Asphalt-aggregate Interface Phase Under The Coupling Effect Of Temperature And Shear Velocity

Asphalt pavement,as the main form of pavement structure that has been vigorously promoted in recent years,brings great convenience and efficiency to people’s travel and,as the artery of national economic development,also affects the growth of a country’s GDP.However,due to the influence of the use environment and service life,asphalt pavement in service for a period of time,there will be different types and different degrees of damage to the road disease,according to a large number of studies found that these asphalt road diseases are related to the asphalt-aggregate interface,so the study of the mechanical properties of the asphalt-aggregate interface to improve the road performance of asphalt pavement has a very important meaning.In order to study the mechanical properties of the asphalt-aggregate interface phase,we first designed a method to effectively control the thickness of asphalt film in asphaltaggregate specimens by ourselves and validated the method.Subsequently,the shear test at the asphalt-aggregate interface was carried out at different temperatures(15℃,25℃,35℃ and 45℃)and shear speeds(5mm/min,10 mm/min,15 mm/min and 20 mm/min)coupled with the WDW-1000 universal testing machine,and the corresponding shear stress-displacement curves were obtained,and the key parameters in the curves were extracted and analyzed.The key parameters in the curves were extracted and analyzed,and finally the damage surface after shear fracture was analyzed by scanning electron microscope(SEM)test.The results show that: the stress-displacement curve of asphalt-aggregate interface is similar to a "single hump",the shear stress reaches the maximum value with the increase of shear displacement,and then decreases rapidly until the residual state;the stress-shear displacement curve is approximately linear before and after the peak of shear stress;the shear strength of asphalt-aggregate interface changes with temperature and shear speed.The shear strength of the asphalt-aggregate interface changes with temperature and shear speed,at the same test temperature,the shear strength increases with the increase of shear speed,at higher temperatures,the shear strength increases with the shear speed is relatively low,while at low temperatures,the increase of shear strength is relatively high,the shear strength is sensitive to changes in temperature;at the same shear speed,the shear strength gradually decreases with the increase of test temperature,the shear Among the 16 sets of test data,the test temperature of 45℃ and shear speed of 5mm/min showed the smallest shear strength,and the test temperature of 15℃ and shear speed of20mm/min showed the largest shear strength at the asphalt-aggregate interface,i.e.,under the condition of larger shear speed and lower test temperature,the asphalt-aggregate interface would produce larger peak shear stress,while at smaller shear speeds and larger test temperatures,the asphalt-aggregate interface produces a smaller peak shear stress.The shear test follows the time-temperature equivalence principle.Microscopic observations of the shear damage surface revealed that the shear tests at low temperatures(15°C and 25°C)were dominated by cohesive-adhesive mixed failure,while the shear tests at high temperatures(35°C and 45°C)were dominated by cohesive failure.