Research On Mechanical And Functional Properties Of High-toughness Ultra-thin Friction Course

In recent years,the country has been committed to advocating the “resource-saving and environment-friendly” social development strategy,requiring the construction of roads with environmental protection,low carbon,energy saving,emission reduction and noise reduction.Therefore,it is urgent to seek a green and economic road maintenance technology to improve the existing road condition and extend the service life of the roads.Under this background,the wear course maintenance technologies such as Nova Chip,micro-surface,SMA overlay and UTAC have been widely promoted and applied,which have improved the pavement service quality and achieved certain economic and social benefits.However,due to the reduction in thickness,the mechanical performance requirements have been greatly improved,and with the limited performance of asphalt materials,it is prone to appear the diseases such as reflection cracks,peeling,potholes and passages,which limits its further application.In view of the technical defects of the ordinary ultra-thin wear course,this paper used the high-performance asphalt binder and tack coat as raw materials and designed a dense-skeleton gradation with thick asphalt film based on the Coarse Aggregate Voids Filling Method,to form the high-toughness ultra-thin friction course technology.Verified by various road performance tests in lab,the high toughness ultra-thin friction course has satisfactory high-temperature stability(the dynamic stability > 5000cycles/mm),water damage resistance(the residual Marshall stability and residual strength ratio in freeze-thaw test > 85%),anti-strip ability,(the scattering loss < 8%),and interfacial bonding and anti-shear performance(The debonding strength and anti-shear strength > 0.4MPa).The anti-cracking performance and anti-skid durability of the thin overlay are the key factors that directly affect its service life.This paper tests the fracture toughness and fatigue crack resistance of high-toughness ultra-thin friction course under different loading modes by designing four test methods such as low temperature bending test,impact ductility test,semicircular bending fracture test and four-point bending beam fatigue test.In addition,with the application of high-precision three-dimensional laser scanning and pressure film testing technology and the traditional anti-skid performance test,the rubbing test was designed to obtain the changing trend of surface structure and interface contact characteristics of the hightoughness ultra-thin friction course in different rubbing stages.The test results show that the high-toughness ultra-thin friction course has better fracture toughness,fatigue cracking resistance and anti-skid durability,compared with the traditional wear courses such as GAC-16 and SMA-13,which is closely related to its dense-skeleton gradation with thick asphalt film.The high-toughness ultra-thin friction course has been applied in various practical projects.Combining the technical characteristics,laboratory analysis results and field construction characteristics of the high-toughness ultra-thin friction course,this paper puts forward a complete construction process covering the original pavement disease treatment,interface disposal,asphalt mixture preparing,field paving,rolling compaction and so on.The analysis of the sample data obtained from the field quality test shows that the high-toughness ultra-thin friction course has superior cracking resistance,anti-skid performance,anti-permeability,noise reduction performance and flatness repair ability.And according to the results,the technical indicators required for the acceptance of this technology have been proposed.This paper has completed a series of work,such as material composition and gradation design of the high-toughness ultra-thin friction course,road performance analysis in lab,field application and quality verification,etc.The research can enrich the current road maintenance schemes and further improve the quality and service life of roads.Besides,it can also provide technical support and reference for the design and construction of high-performance thin overlay.