Comprehensive study on the porous asphalt effects on expressways in Japan: based on field data analysis in the last decade

Porous asphalt has spread widely across Japanese expressways as the standard surface course material since 1998, greatly contributing to the decrease in the number of traffic accidents on wet surface conditions. On the other hand, due to rainwater penetration through the porous surface, water sensitivity of the binder course layer becomes a key issue to secure its durability. This paper summarises the successful performance of porous asphalt surface courses based on a long-term survey over nearly 15 years in fields, also describing the negative impacts of porous asphalt. The experience shows that the durability of the binder course should be taken into consideration when a porous asphalt surface course is applied over old existing roads. This is vitally important if porous asphalt is to perform its excellent functions over a full service life by avoiding unexpected damage of the pavement.