Research On The Dense Framework Gradation Scope Of AC-13,AC-20 Asphalt Mixture

Asphalt pavements have been widely used along with the fast development of highway,which put forward higher quality requirement for it. With the highway acquire quantity development,it also exists some hidden trouble in quality. Because our country is vast territory, and regional climate conditions and traffic conditions are very different, as a national standardized technical guidance and control standards necessary to cover all situations. but given the larger class with a specific scope of work has given each of the mixture designed to bring a lot of difficulty. The realistic question that the general engineer's and technicians faced is how to chose the most suitable design gradation scope that apply to each project in a wide scope of gradation.This article focused on the typical aggregate of the up layer and the middle layer, which is used in asphalt pavement. 4.75mm as the boundary of the fine and coarse aggregate, it will carry on the graduation combination ram density experiment, using the gap of coarse aggregate which is obtained from the experiment as a appraisal target. Then using the closest heap as the principle to decide the gradation scope of coarse aggregate.At the same time taking the CBR test,the test of combination is the same with the ram test. CBR test used to evaluate the coarse aggregate skeleton, the bigger value of CBR test, the stronger the skeleton. The principle of the fine aggregate is filling and does not interference with coarse aggregate structure .It unify the Superpave's design thought and 4% of design's percentage of gap rate determination then combine with the coarse aggregate to calculate the total rate of volume of fine aggregate. The mutual proportion of fine aggregate will use distribution; its gradation scope will unify the construction technology standard to allow the undulation scope which is determined. From this obtains aggregate gradation scope and the optimized design of the rate of gradation of AC-13,AC-20 asphalt mixture. Though the synthesis appraisal among the volume target and the high temperature stability and the water stability to choose the best grading curve. This design method is difference from other popular design methods among the domestic and the foreign counties, put forward a design method for Asphalt mixture. This will do helpful to the development of the asphalt pavement in our nation.