Mechanical Behavior of Composite Structures of Wearing Course and Underlying Layer for Asphalt Pavements
The interlayer bonding state of pavement structures changes due to the influence of various factors under service conditions,and this change exhibits a significant influence on the mechanical behavior of pavement structures.Through the composite structure test and numerical analysis,the mechanical behavior of the composite structure of different wearing courses and underlying layers under different stresses and bonding states was studied.The test used three commonly used wearing course(surface layer)materials of asphalt pavements,namely AC-13,OGFC-13,and SMA-13 for comparative analysis.The test results show that different composite structures exhibit different interlayer bonding properties and fatigue characteristics due to the difference in material properties.Compared with the composite structure of AC-13 + AC-20,OGFC-13 + AC-20 and SMA-13 + AC-20 have stronger shear fatigue resistance but weaker flexural and tensile fatigue resistance.The interlayer compression-shear failure mainly occurs at the interlayer interface and the interfacial transition zone.The compression of the void structure of the material and the interlocking deformation of the bonding interface can be observed.The local interface will have the aggregate destroyed during the extrusion and shear process,accompanied by shear deformation and slippage of the interface.The fatigue failure behavior of composite structures under flexural and tensile stress is obviously different from that under compression and shear stress.The difference in material properties has a significant effect on its flexural and tensile deformation resistance,and the fatigue failure mode is affected by interlayer bonding and interlocking.With the development of material damage,the cracks develop upward from the bottom of the composite beam specimen along the periphery of the aggregate.When the cracks reach the interlayer interface,they develop laterally along the interface to cause local deadhesion and then develop upward until the failure of the composite structure specimen.
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