Applicability Study On Semi-flexible Materials As The Rut-resistance Functionallayer Of Asphalt Pavement

With the development of highway construction and the improvement of the quality of pavement design and construction quality,structural strength and service life of pavement has been a qualitative change.However,due to increased heavy vehicle traffic,particularly the growing overloading and the overstandard vehicle,rut has become a major problem that high-grade highway asphalt pavement maintenance needs facing.For years,modified asphalt has been used as the method to improve the ability to resist permanent deformation of asphalt mixture pavement and almost all possible modified asphalt ways have been tried.The effect was not satisfied,but construction costs have increased.Therefore,there is an urgent need to find a cost effective way to solve the heavy traffic asphalt pavement rutting problems.Lots of study and practice shows that filling porous asphalt mixture as the matrix with special cement slurry is semi-flexible pavement material that has better fatigue resistance properties,higher compressive strength and shear strength than modified asphalt mixtures,as well as lower cost,easier construction.For a long time,because it relies on experience design,quality of instability,in particular its potential cracking risk limiting the application of semi-flexible pavement materials,mostly used at traffic lights or near bus stop area and other applications requiring high shear strength environments.If the problem of semi-flexible pavement materialwe can be solved,to overcome their problems and fulfill its potential,as well as using this material as the rutting resistance functional layer of high grade highway asphalt pavement structure,the social and economic benefits would be enormous.In view of main technology risk of semi-flexible pavement material is deformation compatible of asphalt and cement material that will lead to cracking problem,this research usingmulti-scale mechanical analysis,calculated ultimate strain of porous asphalt mixture,the design index system of volume stable type of cement slurry have been established,the design method of volume stable type of cement slurrywas suggested,for validationof research results,the entity engineeringtest road was built also.The test and observe to entity engineering test road shows that the good technical and economic results of this study have been achieved.This research focuses on semi-flexible pavement materials as a rutting resistance function layer of asphalt pavement structure,the main research work and results are summarized as follows:1.From the perspective of pavement cracking,with digital image technology and finite element analysis method built semi-flexible pavement material mechanics model,calculated ultimate strain of porous asphalt mixture,established design index system of volume stable type of cement slurry.On this basis,the design method,has been declared national invention patent,based on mechanics for semi-flexible pavement material was developed that will be a good foundation to promote semi flexible pavement material use as rutting resistance functional layer of asphalt pavement structure.2.The affectof temperature stability of cement slurry volume on internal stress level and distribution state ofsemi-flexible pavement material was analized.An optimization research on proportion and material making up cement slurry was carried out based on the working performance(that appropriate of flow degrees)and physical mechanical performance,the volume stable type cement slurry design method has been develped,3 types of volume stable type cement slurrys are recommended that can meet the minimum requirement of asphalt matrix.3.5 typical pavement structure models is designed,taking into account the effect of temperature on modulus of materials on the basis of,by finite element method analysis of stress response of pavement structure shear stress distribution of pavement,proposed the concept of pavement structure rutting resistance function layer,and semi-flexible material as a function of asphalt pavement structure rutting resistance of technical and economic advantages.Analysis and test results,with semi-flexible pavement structure rutting resistance of asphalt pavement materials as functional layers are feasible,and with great technical and economic effects.