Yusuke SHIMAZU

Study on Mixture Design of Stone Mastic Asphalt Wearing Course for Bridge Decks

Osamu TAKAHASHI

Stone Mastic Asphalt (SMA) has better plastic flow resistance and impermeability than dense-graded asphalt mixtures. In Japan, SMA has been used on a trial and experimental basis, but some problems were pointed out in terms of strength and construction. On the other hand, damage to slabs due to rainwater infiltrating through bridge deck pavements has become a serious problem, and the need for an impermeable wearing course has increased. In the United States, the SMA which standardized by American Association of State Highway and Transportation Officials (AASHTO SMA) is widely used for a long time. The AASHTO SMA does not have the same problems as the Japanese SMA. However, the AASHTO SMA is not applied in Japan, and knowledge of its applicability to bridge deck surface is not clear.
The present study designed the AASHTO SMA using common Japanese aggregate and asphalt binder, and evaluated the basic properties required for application to bridge deck wearing course in comparison with conventional mixtures for wearing courses. Dominant design parameters and their adjustment tips were also explored.
The test results illustrated that applicability of the AASHTO SMA was sufficient to the wearing course for bridge decks. The AASHTO SMA can be designed by controlling the VMA and adjusting the particle size distribution of fine aggregates.