KentaĦĦSUZUKI
Studies on the damage situation and occurrence factors in the asphalt pavement of Expressway
Osamu Takahashi
The asphalt pavement of Expressway in Japan, weakening of the subbase course and asphalt stabilization base course with the passage of years in-service has become a serious problem. Accordingly, it is expected that in the near future, repair of the subbase course is needed in many routes. And materials used pavement structure in that case, is required specifications to ensure the long-term durability further. However, since the basic data necessary for the development of long-life technology is insufficient, repair design method for realizing it has not been established. Therefore, basic research to develop technologies to make a long life of the asphalt pavement in expressway is required.
In this study, I analyzed the results of the excavation surveys conducted on route from highway in Nagano Prefecture.
As a result, thickness of the asphalt concrete layer is large, and subgrade and subbase course is a healthy state, was confirmed cracks to progress downward from the road surface. However, bearing capacity of the overall pavement structure is very large. On the other hand, at the point where permanent deformation has occurred in the lower layer subgrade, cracks progresses upward from the bottom surface of the asphalt stabilization layer roadbed (hereinafter, bottom-up cracking) was observe. In that case, the supporting force of the entire pavement structure was smaller than other places. I also compared the crack resistance of each asphalt concrete layer. In addition, I compared the fatigue fracture resistance of each asphalt concrete layer. As a result, I could be confirmed that durability of asphalt stabilization upper roadbed is lower than the others. And I confirmed that cyclic loading due to traffic reduces the durability of the asphalt concrete layer.
From these results, fatal damage of asphalt pavement was found to be a bottom-up crack caused by permanent deformation of the subbase course.
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