A Comparative Study On Different Design Methods For Asphalt Mixtures

A good mix proportion design is an important prerequisite that guarantees theperformance of asphalt mixture and the performance of asphalt pavement. In order toensure a good mix proportion design of the asphalt mixture, a reasonable designmethod becomes particularly important. In the1970s, our country began to use theMarshall method for the design of asphalt mixture; and it has been included in thespecification since then and is still in use today. In abroad, the Superpave asphaltmixture design method developed developed during SHRP Program in the U.S. is awidely used method. Besides, the specimen vibrating compaction, which simulatesthe vibrating compaction of pavement construction, makes another method of asphaltmixture design.This thesis is based on Heng-Gui Expressway (Hengyang to Guiyang) Project.According to the actual situation of the project and the design of the traffic volume,this thesis makes a comparative study on different mixture design methods of asphaltmixture. Adopted asphalt mixtures include: AC-20C for Marshall design methods, theSup-19(Superpave19mm) for Superpave design method, AC-20C for vibratingcompaction design method.The design indices of the three design methods of asphalt mixture are not thesame. As for the optimal asphalt aggregate ratio, The Marshall method is4.4%,Superpave method is4.1%, and the vibrating compaction method is4.2%. Under theoptimal asphalt aggregate ratio, the order of air voids is: Superpave method﹥vibrating compaction method﹥Marshall method; the order of Marshall Stability is:vibrating compaction method﹥Marshall method; the order of Marshall Flow is:Marshall method﹥vibrating compaction method; the order of specimen density is:Superpave method﹥vibrating compaction method﹥Marshall method; the order ofVMA is: Marshall method﹥vibrating compaction method﹥Superpave method; andthe order of VFA is: Marshall method﹥vibrating compaction method﹥Superpavemethod.The performance test results show that asphalt mixtures designed with the threemethods all meet the requirements of JTG F40Technical Specifications forConstruction of Highway Asphalt Pavements. The order of high temperature stabilityis: Superpave method>vibrating compaction method>Marshall method; the order of moisture stability is: Superpave method>vibrating compaction method>Marshallmethod; and the order of low temperature cracking resistance is: Marshallmethod>vibrating compaction method>Superpave method.