| China's highway construction has experienced 20 years of rapid development, which is the same as the development of the developed countries in the past decades, and achieved a brilliant success. For a long time, the gradation and nominal maximum aggregate size of upper-layer asphalt mixture are chosen by experiences. The gradation is composed of AC, AK, SAC, etc., and how to chose gradation according to practice is the aim of the engineers. Fractal theory has been used in gradation design in recent years, and there's a problem deserving research: the relationship between fractal dimension and pavement performance index of asphalt mixture.Consequently, there's two parts in this paper: First, comparative research on pavement performances of different gradation, which is used to analyze the differences between pavement performances and make gradation optimization on the basis of grey relation theory. Second, by means of analyzing the relationship between gradation parameter and pavement performance index, there's conclusion that when D=2.30, dynamic stability of single-layer rutting is relatively high as CA is about 0.40; when D=2.20, dynamic stability of composite rutting is relatively high as CA is about 0.40 and the decline of dynamic stability is relatively small; when D1>2.40, ultimate bending extensibility is good as CA>0.52. In addition, there's no obvious relationship between TSR and gradation index.In this paper, pavement performance is used as evaluation index, and systematic research on upper-layer asphalt mixture is done, which is useful for chose on gradation. Further more, there's analyze on relationship between pavement performance and gradation index, which is very useful for the application of fractal theory in gradation. |
