Study On The Optimizing Mix Design Based On Particle Shape Of Coarse Aggregate

With the perfection of the national expressway network, the accessibility, high efficiency, convenience and safety of transportation have been promoted dramatically. But various damage has been destroying constructed pavement. Especially rutting could be found on a national scale, affected performance of asphalt pavement seriously, reduced the level of service sharply, and increased the cost of operating and using. It has been proven in practice that besides of over loading and natural aging, the main factors which caused pavement damage was gradation of aggregate mixture. Therefore, the study of optimizing mix design must be enforced.The mix design depended heavily on the design experience. Existing optimization methods, from adjustment, emphasized on macroscopic factors, such as the size of aggregate. But it has been proven that the performance of aggregate mixture had relation not only with the size of aggregate but also with the shape, standard, and texture of aggregate. But existing mix design method only considered the size of aggregate, and cannot make out the best result. So it has important meaning that analyze the factors of mixture multiscale and studying the method of mix design.This paper launched research on the microscope of aggregate, using the image processing technique, studied deeply the characters of aggregate, and proposed parameters characterizing the shape of aggregate. On the condition that different aggregate had different contends, this dissertation conducted performance tests, searched the principle of parameters, studied the quantification method of gradation curve on the basis of fractal theory. This paper also utilized SPSS to analyzed and worked out the mathematical relationship between the parameters of aggregate shape and the performance of mixture, and amended the model through test.The model proposed by this paper reflected the combined influence of gradation and aggregate, which offered theory basis for optimizing mix design. If the aggregate and gradation were given, the mixture performance can be calculated by the model. Therefore the primitive design can be adjusted, which promoted the efficiency of mix design. The conclusion can be used in mix design, and had great meaning on reducing pavement damage.