Research On Fracture Properties Of Emulsified Asphalt Cement Mortar Based On Viscoelastic Properties

Emulsified asphalt cement mortar is a new type of composite material,which is mainly composed of emulsified asphalt,cement,fine sand,water and some additives,and is widely used in the field of transportation infrastructure.In the application of slab ballastless track structure,semi-flexible base and bridge deck pavement structure,emulsified asphalt cement mortar often fractures due to temperature stress and reflection crack problems.At the same time,due to the presence of asphalt,the fracture characteristics and influencing factors of emulsified asphalt cement mortar are more complicated.This paper mainly studies the fracture process and fracture mechanical parameters of emulsified asphalt cement mortar.The raw material performance of emulsified asphalt cement mortar was tested,material ratio was selected,and experimental research plan was determined.The semicircular specimens and beam specimens were formed separately,and these test specimens were cured.The fracture mechanics test plan was determined,test specimens were cut and cracks of different depths were prefabricated.The basic theories of linear elastic,elastic-plastic and viscoelastic fracture mechanics were compared and analyzed,and the differences in fracture parameterrs and fracture criterion under different theoretical frameworks were analyzed.The fracture mechanical properties of semicircular bending specimens and beam bending specimens were studied basing on the fracture test.The form of load-displacement curve was compared and analyzed.The numerical values of different fracture mechanical parameters were calculated.Effects of material ratio,crack depth,loading rate and temperature on the load-displacement curve were studied.The changes of fracture mechanical parameters such as ultimate load,fracture toughness and fracture energy were studied.Fracture parameters continue to increase with the decrease of temperature.The change of fracture parameters with material ratio has a peak in the middle when temperature is low.The fracture process of emulsified asphalt cement mortar was studied basing on the digital speckle method.Based on the basic principles of digital speckle method,research plan for digital speckle was determined.The displacement field,strain field and crack propagation path of specimens with different crack types were studied.The fracture process of emulsified asphalt cement mortar was studied,and characteristics of different fracture stages were analyzed.Based on the change of crack opening displacement,the fracture process was divided into three stages,crack initiation,stable propagation and fast crack propagation stage.Based on the viscoelastic fracture numerical simulation analysis model,the fracture process and fracture parameters of emulsified asphalt cement mortar were studied.The numerical analysis method of fracture process based on the viscoelastic constitutive model was determined.The parameters of viscoelastic material were analyzed basing on the creep test.Based on the extended finite element method and contour integral method,the fracture process of emulsified asphalt cement mortar was studied,and the changing rules of fracture parameters were analyzed.The stress distribution and energy dissipation during fracture were analyzed.