Research On The Stability And Durability For The High Viscosity Modified Asphalt And Porous Asphalt Mixture

In recent years,based on the development concept of "environmentally friendly and resource saving",road infrastructure has paid more attention to the harmonious development of the ecological environment and drainage system.In particular,urban roads are no longer limited to simply satisfying the basic traffic of pedestrians and vehicles,but gradually complement the use environment and ecological construction,which undoubtedly puts forward higher requirements on the material performance and structural functions of the road.Porous asphalt(PA),as a distinct mixture type that deliberately designed with stone-on-stone contact of the coarse aggregate fraction and high percentage of interconnected air voids to obtain the safety,comfort and environmental benefits,is one of the desirable solutions for the strategy of Sponge City proposed by China in 2012,it seems to have a wide range of potential applications for supplementing traditional urban drainage systems.However,compared with Europe,America,Japan and other countries,the practical application of PA mixture in China is still in the initial stage.On the one hand,there is a lack of high-viscosity modified asphalt that is economical,applicable and compatible with the local climate and traffic;on the other hand,the temperature stability and durability of PA mixtures are generally insufficient,which restricts its further application and development in my country.In view of the above situation,this paper intends to carry out research in the following aspects.Based on the analysis of the action mechanism and properties of 6 types of thermoplastic elastomers,tackifiers and plasticizers,the material design and preparation of high-viscosity modified asphalt are systematically carried out,and 4 types of applicable elastomers are determined.The multi objective orthogonal range analysis was introduced to reveal the effect of different material components and contents on the 6 main technical indicators of high-viscosity modified asphalt.3 types of high-viscosity modified asphalt were developed with good rheological properties,and the mechanism of modification and aging were explored separately.The effects of aging,water immersion and low-temperature conditions on the adhesion between asphalt and aggregate are considered.The morphological characteristics and nanomechanical properties of the three types of high-viscosity modified asphalt under single and complex micro-scale conditions are explored with the aid of atomic force microscope.The tensile test method has been improved,and the adhesion failure laws of the three types of high-viscosity modified asphalt and aggregates under single and complex macro-scale conditions have been studied;combined with the microscopic adhesion mechanism and the macroscopic failure characteristics,the composition design of the high-viscosity modified asphalt has been studied.optimization.Based on particle interference theory and stacking theory,the penetration strength,void distribution and aggregate contact characteristics of typical continuous gradation,discontinuous gradation and discontinuous composite gradation designed by multi-stage filling skeleton and main skeleton void filling method are compared.The effect of the flat and elongated aggregates on the volume characteristics of aggregate gradation is simulated by the discrete element virtual test.Based on this,laboratory tests were carried out.The effects of different slenderness ratio and content of needle flake aggregate on the penetration strength,void distribution and aggregate contact characteristics of discontinuous composite gradation were studied.The gradation design and flat and elongated particles limit of PA mixture were discussed.The sensitivity and reliability of various stability and durability test methods to porosity and specimen size are analyzed.The high temperature dynamic creep failure and low temperature restrained stress freeze fracture characteristics of PA mixture are studied;The effect and mechanism of PA mixture to resist splitting failure and aggregate spalling under the coupling effect of different mixture aging and freeze-thaw cycles were explored;The effect of mixture aging on indirect tensile strength and fatigue life was studied.On this basis,the law and mechanism of a variety of typical modified asphalt,engineering fiber and filler on the temperature stability and durability of PA mixture are studied,the relationship between common diseases of PA pavement and asphalt properties and mixture performance is analyzed,and the applicability of different technical schemes for common diseases of PA mixture is discussed.