Kikuo Nishioka
Study on design method of hot asphalt mixture using Superpave gyratory compactor
Osamu Takahashi
Marshall method has been used as the standard procedure of hot mix asphalt (HMA) design since the 1960s in Japan. This procedure uses Marshall hammer for compaction of HMA specimens. However it has been pointed out that Marshall hammer is not appropriate, because the hammer compaction cannot simulate field densifications.
On the other hand, Superpave method, which was developed in the 1990s in USA, utilizes gyratory compactor for preparing HMA specimens. Gyratory compactor simulates field aggregate orientation better than Marshall hammer because of its kneading action. Gyratory compactor has not been applied to actual design works in Japan, even though it is widely recognized that gyratory compactor is more suitable than Marshall hammer. The reason is that Japanese HMA engineers don”Ēt have any guideline for utilizing gyratory compactor.
The objective of this study is to establish a guideline for mixture design using Superpave gyratory compactor. As Japanese HMA engineers have a long history and huge data of Marshall method, this study discusses a revolution number of gyration with taking Marshall compaction into account.
From the discussion of the study, the following findings were obtained.
1) It is valid that number of gyration for the traffic level of B under is 40, and that for the traffic level of C over is 45.
2) A HMA mixture designed by the developed standard in this study is almost the same as the mixture designed by Marshall method. The developed design method can be applicable to Japanese HMA design works
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