Takashi SEYA
Fundamental Study on Application of Superpave Mix Design to Japanese Airfield Pavements
Osamu TAKAHASHI
A life extension of airfield pavements is recently needed in Japanese airports because of the increase in aerial demands. An increase in the number of the aircraft taking off and landing has introduced early fail in asphalt pavements, even though the design life is set up for ten years. The increase of repair works causes the increases of maintenance expense. Therefore, design and construction methods of asphalt mixtures with higher durability have been required year by year.
Hot mix asphalt (HMA) mixtures in road and airport pavements are designed using Marshall design method. The current Marshall design procedure has abundant experiences in a long history. However it is pointed out that flexibility and rationality are insufficient for recent diversification of souse materials and heavy traffic condition. In the United States and Canada, Superpave design method was developed as a HMA design method with high durability and rationality for heavy traffic road. Superpave design method have been adopted not only in the United States and Canada but also in Europe and Asian advanced countries. Practical use of the method to road pavements is almost completed in the United States, and application to airfield pavements is investigating.
Based on the present state of domestic airports, especially Tokyo International Airport, this study examines a HMA design method which is excellent at resistance of plastic flow deformation. The objectives of the study are to decide a procedure specification in order to introduce Superpave design method into asphalt pavements in Japanese domestic airports, and to obtain fundamental data for architecting the design guideline. Review of the design standard and evaluation for applicability of Superpave design method are also included in the objectives.
Specification of the souse materials used in Tokyo International Airport and Kansai International Airport were firstly investigated as well as the actual compaction situation. Then, the compaction test was carried out using the equal souse materials and the compaction condition of a HMA specimen on the mixture design procedure was decided from the results. It means that the design number of gyrations, Ndes, for Superpave Gyratory Compactor (SGC) was fixed. SGC device is able to create an actual compaction state of asphalt concretes in the design process.
Some aggregate gradations were blended following the guidance of Superpave design method and the current design method, and design asphalt contents were determined following the requirements and procedures of Superpave design method. HMA characterization was compared between the asphalt concretes designed by current Marshall design method and Superpave design method. Applicability of Superpave procedures and requirements was evaluated from the comparison results.
Base on the results, this study indicates that Superpave design method can design a asphalt concrete which is excellent in resistance of plastic flow deformation for airfield asphalt pavement, and is especially effective for taxiway for airfield asphalt pavements. In addition, the study shows some useful findings on application of Superpave design method to Japanese airfield pavements under the weather condition of high temperature and high humidity.
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