Study on the application of grading theory

By studying the maximum density curve theory,particle interfering theory and different grading calculus,the varying i method and calculating formula were put forward to grading design.Then the ranges of i were presented to AC-16,SMA-16 and Sup-12.5 according to contrast aggregate gradations from varying i method with AC-16,SMA-16, Sup-12.5 and skeleton dense structure gradation designed on particle interfering theory.Furthermore,it was verified by applying the varying i method to the grading design for AC-16 mixture on the basis of practice in project.The result shows it can satisfy well the design request by using the method to design aggregate gradations.At the same time the varying i method adapts preferably to the square-mesh sieve in asphalt mixture and design request of aggregate gradations for different kinds of asphalt mixtures.