Study On Grading Segregation Description Of Asphalt Mixtures And Related Problems Based On Fractal Theory

Aggregate segregation is a serious problem in the construction of asphalt pavement. Aggregate segregation leads to some problems, for instance asphaltmixture can not accord with the requirements for gradation and asphalt content inmix design in specifications, and there are certain differences between the indexes, such as density, air voids, stiffness, tensile strength and fatigue life of bituminous mixtures, and design value. This results in accelerated normal pavement distresses such as raveling, cracking, fatigue, rutting and so on.In the last few years, aggregate segregation is paid attention to in many researches. However, the problem that what method and index are chose to evaluate aggregate segregation quantitatively isn't resolved well. Meanwhile, the influence ofaggregate segregation of different degree to mechanical properties of asphalt mixture demands prompt solution for the research of aggregate segregation.Fractal is a new theoretical tool to study lots of statistical self-similatity characteristics in nature, and it has a powerful function in describing and evaluating those phenomena continuous in scale, erose in shape or stochastic in distribute. There are so many self-similarity characteristics in asphalt pavement from the selection of raw materials, the design of gradation, until to the construction of pavement. Traditional indexes based on experience are difficult in describing and evaluating, so we can turn to the fractal theory to give them a quantitative analysis. Based om the fractal analysis and in-door tests, this paper brings forward the fractal evaluating model of gradations.Segregation by the laboratory to simulate different levels of asphalt mixture, including the choice of method of gradation, asphalt content of the segregation level with the setting. Ma made the isolation level of the specimen to determine the density of mixture, for the subsequent isolation level of each mixture to provide the basis pavement performance test; given mixture of various segregation fractal dimension methods of calculating fractal mixture fractal dimension and the mixture temperature stability, water stability, low temperature cracking resistance and so the relationship between pavement performance.Gradation by segregation analysis on the characteristics, on the one hand, to the road surface characteristics of index --- structure to reflect the depth of asphalt mixture segregation, to level with fractal dimension value of the bridge, the establishment of road surface texture depth and set the relationship between the gradation; the other hand, by grading fractal dimension, the establishment of mixture gradation segregation fractal dimension and porosity graded mixture segregation and other parameters. Application of asphalt content analyzer mixture of different levels of segregation were burning, and for screening of all files aggregate pass rate to calculate the fractal dimension value, try to establish a mixture of various degree of segregation in the surface of the depth and verify the grading structure of fractal the relationship between fractal dimension.Finally, from the point of grading and stability control index for raw materials upon request; by existing dense built Mixture Design Methods, by using the constrained uniform design method to choose the coarse aggregate gradation, using a continuous dense gradation formula to determine fine aggregate gradation, design principle according to the volume level with the synthesis and adjustment; of the fractal theory based on the anti-segregation grading stable dense built Mixture Design.