Research On Conventional Volume Index And Aggregate-Void Correlation Model Of Asphalt Mixture

The volume composition of the asphalt mixture mainly includes three parts: aggregates,asphalt and voids.It is one of the main influencing factors of the overall service level of asphalt pavement.Due to the large differences of shape,size,distribution characteristics of the aggregate particles,the distribution of asphalt and characteristics of void are also complex.Therefore,the establishment of the association between the aggregates and voids is of great significance to the volume design of the mixture.The surface theory and mortar theory are two different theoretical basis for the composition of the asphalt mixture.The former divides the mixture into mineral aggregates and binder,aggregates provide strength and binder provides adhesion.The latter believes that the mixture is the dispersion of multi-level spatial mesh structures,and it divide the mixture into micro dispersion,fine dispersion and coarse dispersion.In this paper,two aspects of the macro-volume index and meso-volume characteristics of the mixture are used,and three research methods for numerical calculations,image analysis,and experimental tests are studied for the volume characteristics of the asphalt mixture,including the following research content:(1)Based on surface theory and mortar theoryy to calculate the conventional volume index of the mixture,the reasonable range of the conventional volume indicators of the mixture is proposed;(2)Propose a film thickness calculation formula of the dispersion medium based on the dispersion system based on the equivalent ball theory,and links the volume of the asphalt material film thickness and the dispersion of the dispersion of the dispersion system at all levels;(3)Based on the AVIZO image processing technology and X-Ray CT non-destructive scanning technique to obtain image slices of mixture,a mixture processing method capable of identifying a void,a mortar,and a aggregate,and applies 3D printing techniques to Asphalt mixture analysis;(4)Verification of the volume index relationship proposed by the three typical structures through indoor molding mixture samples,and analyzes the distribution of aggregates-gap distribution in three typical structures.Through the research and analysis of the system,the following conclusions are obtained:(1)Adopt the simple-nomo-diagram to propose an empirical model of the relationship between the volume index of the asphalt mixture.Propose a mixture design method based on the empirical model of the relationship between the volume index of the mixture and the film thickness of asphalt materials;(2)Separate identification of the aggregate and voids of the dense grading mixture,using the distribution characteristics,volume,surface area,and equivalent diameter characteristic of the surface voids,the size characteristics of the spherical characterization of the sphere;(3)The concept of void grading of mixture is put forward to study the correlation of distribution characteristics between aggregate and void of dense grading mixture.It is concluded that the more fine aggregates in the aggregate composition,the more uniform the void distribution.The above studies have an in-depth understanding of the volume characteristics of the asphalt mixture,providing a strong support for the mixing ratio of the mixture based on volume indicators.