Study On The Segregation Causes And Cures In Asphalt Mixture

The segregation of asphalt mixture has been duly noted as the increasing of asphalt pavement in our country. But at the present time, there is no systematic study on the mechanics, influencing factors and control measures of mixture segregation in our country. This paper studied on the segregation of asphalt mixture by means of inside and outside tests and theoretical analyzes.Firstly, the paper investigated and analyzed the influence that mixture segregation brings to the new pavement, and then studied the relationship between segregation and pavement early damage integrated with the investigation of pavement early damage. Inside test indicates that only the segregation of coarse aggregate will not influence the mixture’s water-stability obviously. This paper attempted to analyze the mechanics of mixture segregation by the theories of granulation, mixture design, and heat transmission, and got some conclusions, also studied the methods and technology for detecting segregation as well.This paper studied the segregation characters of asphalt mixture with different gradations depending on the construction of Shag-Zhou express way. Different designs of gradation have different segregation characters, such as maximum density line, "S"-shaped line, inverse "S"-shaped line, curves bowed up or bowed down the maximum density line, and gap-graded mixes. Mean square deviation of the sand-patch diameter between different groups which is distributed at different sites of the helical agitator was selected to flag the segregation characters. Paper studied the correlation between the segregation index and the gradation indexes, such as fractal dimension (D), coarse aggregate ration (CA), coarse portion of fine aggregate (FA_c), fine portion of fine aggregate (FA_f), etc. found that the segregation index correlates with the fractal dimension of 0.075～2.36mm grain diameter, and gave the regression function of the two indexes. In addition, this paper analyzed the causes of segregation during mix design, stockpiling, asphalt facilities, truck loading and unloading, and paving, etc. then gave some solutions to eliminate segregation.