Research On Damage Characteristics And Mechanism Of Emulsified Asphalt Cement Mortar Under Freeze-thaw Effects

Emulsified asphalt cement mortar is composed of emulsified asphalt,cement,sand,water and a variety of admixtures.It is an organic-inorganic composite material formed by cement hydration hardening and emulsion breaking knot.Emulsified asphalt cement mortar is widely used in traffic infrastructure.The freeze-thaw cycle will lead to the deterioration of the performance of emulsified asphalt cement mortar and affect the durability of emulsified asphalt cement mortar.In this paper,the freeze-thaw damage characteristics and mechanism of emulsified asphalt cement mortar are studied.The research scheme of the raw material ratio and freeze-thaw damage characteristics of emulsified asphalt cement mortar was determined.The performance of the raw material was tested,and the raw material ratio,the molding method of the test piece and the curing conditions were determined.The experimental research scheme of hydrophilic property,water absorption property,water reducing law,freeze-thaw property,strength property and microstructure of emulsified asphalt cement mortar was established.The mechanical properties of asphalt and the change of material components under the action of freeze-thaw cycle were determined.Based on the hydrophilic and water absorption tests,the water retention and reduction law of emulsified asphalt cement mortar were studied.The influences of raw material ratio,specimen forming surface and other factors on the contact angle were analyzed.Through the capillary water absorption test of emulsified asphalt cement mortar,the water absorption characteristics of emulsified asphalt cement mortar and its influencing factors were studied.Through the comparative analysis of the moisture content of emulsified asphalt cement mortar and cement mortar with the change of age,the reduction law of free water in emulsified asphalt cement mortar and the effect of asphalt on water isolation and wrapping are studied.Based on the frequency scanning test of asphalt under the action of freeze-thaw cycle,the influence of freeze-thaw cycle on the performance of asphalt material is analyzed.The main curves of complex modulus and phase angle of asphalt are obtained by using the principle of time temperature equivalence.The influence of freeze-thaw cycle on complex modulus and phase angle of asphalt is analyzed.The influence of freeze-thaw cycle on the viscoelastic parameters of asphalt was studied through the fitting analysis of complex modulus with four elements and five parameters model.The influence of freeze-thaw cycle on the characteristic functional groups of asphalt was analyzed by infrared spectrum test.Based on the uniaxial compression test of emulsified asphalt cement mortar under the action of freeze-thaw cycle,the damage characteristics of macro mechanical properties are analyzed.The influence of freeze-thaw cycle and material ratio on compressive strength and elastic modulus of emulsified asphalt cement mortar was studied.Based on the three parameter solid model,the integral constitutive equation is established,and the strength test curve is fitted and analyzed.The influence of freeze-thaw cycle on the viscoelastic mechanical parameters of emulsified asphalt cement mortar is studied.Based on CT scanning test,the microstructure characteristics and evolution law of emulsified asphalt cement mortar were studied.The law of crack ini tiation and propagation under the action of freeze-thaw cycle is analyzed.The micro mechanism of freeze-thaw damage of emulsified asphalt cement mortar was studied.The damage variables that characterize the macro mechanical properties and micro structural properties of freeze-thaw damage are defined,and the relationship between the micro structural damage and macro mechanical properties damage is studied.The freeze-thaw damage evolution equation is established,and the freeze-thaw damage evolution law of emulsified asphalt cement mortar is analyzed.