Takuya Kushida

Study on comparison between compaction properties based on the Marshall hammer and the Gyratory compactor.

Teruhiko Maruyama


The current Japanese procedure of asphalt mix design, called the Marshall method, has been using since the 60�fs. Specimens in this method are compacted using the Marshall hammer, which is an impulsive compaction device for hot asphalt mixtures (HMA). In a mix design procedure, compaction devices are required to simulate a field compaction of traffic loads. However, the Marshall hammer can�ft be sufficient to simulate that phenomenon.

On the other hand, Superpave method developed at 90�fs in USA has utilized the Gyratory compactor to make compacted HMA specimens. The Gyratory compactor well simulates field aggregate orientation because the mechanism generates the kneading action, which is similar to a field traffic compaction.

The Gyratory compactor is recognized as a better compaction device, and has been already introduced and used in many countries. However, it is not introduced to the Japanese design method. The main reason is that the Japanese design method has no guideline yet.

The objective of this study is to develop the guideline for using the Gyratory compactor in the Japanese design procedure. Appropriate numbers of gyration were evaluated from the comparison between densities derived by the Marshall hammer and the Gyratory compactor. Then, based on the number of gyration, applicability of the required volumetric properties that are standardized in the U.S. Superpave was investigated.

From the discussion of the test results, the following conclusions were obtained.
1) It is reasonable that number of gyration for the traffic level under B-class and over C-class are 40 times and 60 times respectively.
2) The standards of Superpave in the U.S. are adaptable to the procedure of Japanese Marshall method.