Study On Typical Gradation And Residual Life Prediction Low Freezing Point Ultra-Thin Wear Layers With Considering Anti-Freezing Ice Ability

Snow icing on road surface is the main problem that affects the safety of driving on roads in cold regions of China in winter.The application of low freezing point pavement makes the existing pavement preventative maintenance and has the ability of snow melting and ice suppression.However,in the actual use process,the effective components in the deep layer of the full-thickness low-freezing point asphalt mixture cannot be completely separated out,which leads to the waste of materials.However,the low freezing point coating will significantly reduce the life of snowmelt due to its rapid release.Therefore,this paper takes the thin overlay as the carrier to design the asphalt mixture layer with low freezing point and ultra-thin overlay,which meets both the road performance and the snow melting performance.However,it lacks the existing design method of ultra-thin wear layer with low freezing point.In this paper,the design method of ultra-thin wear layer with low freezing point will be proposed,the migration and release rules of effective components will be clarified,and the effective snowmelt life of ultra-thin wear layer with low freezing point will be evaluated.In order to better meet the existing pavement maintenance and snow and ice removal capacity needs.First of all,CT technology was used to study the characteristics of meso-structure of different gradation types,and AVIZO was used to reconstruct asphalt mixture in 3D to extract the meso-structure parameters.The correlation shows that the internal pore structure and the degree of tortuosity are the main influencing indexes.0.15～0.29d was taken as the key mesh to control the overall grading,and the grading was divided into skeleton material,interference material and filling material.The grading range was optimized by adjusting the proportion relationship.According to the road performance of the mixture,the grading type and grading range of the asphalt mixture meeting the low freezing point are optimized.Secondly,one-way infiltration was used to measure the release speed of the active component V_OGFC>V_AC-Ⅰ>V_Novachip-B>V_SMA>V_AC-Ⅱ.The effects of meso-structural parameters,such as pore structure and migration path,on the migration and release of active components were investigated.The results show that the pore structure has a great influence on the migration and release of the active components,which proves that the meso-structural composition of the mixture is closely related to the migration and release characteristics of the active components.Thirdly,under different working conditions,the distribution,migration and release rules of effective components under the influence of different migration driving forces such as temperature,age,load,concentration and humidity were explored.According to the test results of the residual active components in the low freezing point asphalt mixture,the diffusion coefficient of Fick’s second law equation is modified by using the correction coefficient of period,temperature,load,etc.Combined with the initial boundary conditions,a residual precipitation model was established to evaluate the release characteristics of active components under different migration driving forces.Finally,through the temperature sensor arranged at different depths of the specimen,measured and plotted the ice-sample cooling step curve,and put forward the solid freezing point index.According to the change of single release concentration,the relationship between the change of internal content of effective concentration and the change of freezing point is established.The ice-melting ability of effective snowmelt ion solutions with different concentrations was explored.Combined with the single release concentration of effective ingredients,the effective working concentration range of effective ingredients was comprehensively determined.Thus,the relationship between concentration change of active components,freezing point change and life prediction was established,and the residual life of low freezing point asphalt mixture at different stages was estimated.