Study On Fractal Evaluation Methods And Control Technology For Asphalt Mixture Gradation Segregation

Asphalt pavement has become the primary type of pavement structure for highway in ourcountry．And the asphalt mixture segregation is one of the main reasons for the damage in theearly stage of the asphalt pavement．In recent years,many research organizations at home andaboard have explored extensively research on the segregation of asphalt mixture. However,these researches were mainly aimed at the asphalt pavement which is finished. Results aredifficult to be applied to estimate the segregation tendency of mixture. On the one hand, thesegregation is caused by the irrational construction and management methods; On the otherhand is caused due to improper design of aggregate gradation. The former can be solved bytaking certain measures during the construction process; unreasonable grading design,however, is difficult to take reasonable improvement methods in the construction practice.Therefore, it is necessary to carry on a further research of mixture segregation characteristicsin the design phase. This paper,supported by Natural Science Basic Research Plan in ShaanxiProvince of China "Prediction for Gradation Segregation of Asphalt Mixture Based on theFractal Theory" and Applied Basic Research Programs of Transportation Application "Studyon Asphalt Mixture Characteristics and Control Method for asphalt mixture Segregation",aims at researching the relationship between mixture gradation and pavement variability.Thenan appropriate evaluation method can be established to ensure the uniformity of the asphaltpavement.Fractal is a theoretical tool to study lots of statistical self-similarity characteristics innature. It has a powerful function in describing and evaluating those phenomena continuous inscale, erose in shape or stochastic in distribute. The internal distribution and volumeindicators of Asphalt mixture aggregate materials have significant scale-free (self-similarity),which can be given a quantitative description by fractal theory. From the view point ofaggregate size distribution function, this article has derived an aggregate fractal characteristicscalculation method. And a unified evaluation method of fractal has been established based onthe asphalt mixture gradation fractal characteristics.Through the construction of roads, the segregation tendency toward the characteristics ofthe different gradations asphalt mixture has been studied. The field test results show thatmixture gradation type has absolute influence on asphalt pavement segregation. Gradationcharacteristics can be used to distinguish between potential segregation characteristics of themixture and to provide a reference basis for grading design. For AC-16and AC-25asphaltmixture, we have studied the relationship between the gradation segregation indicator S and aggregate by using gray correlation analysis and mathematical statistics methods.SPSS statistical software analysis found that a good correlation exists among fractaldimension、segregation graded index and the road surface texture sub-dimension values andgraded mixture segregation index, graded to have a good correlation between the segregationindex and the depth of the pavement structure, and the corresponding modes have beenestablished. By using the segregation graded index as an intermediary, a relationship betweenroad surface texture and fractal dimension is established. And reference existing segregationevaluation and norms, the segregation evaluation methods have also been proposed forAC-25.Finally, in order to ensure the stability of asphalt mixture pavement, a reduceinggradation segregation asphalt mixture design method is proposed. By studying the wholeproduction process of asphalt pavement construction, the article analyzes the main factors thatcause road graded variation, and specific some measures for the control of Asphalt PavementConstruction Segregation.