Mix design and application of porous asphalt pavement using Japanese technology

Early applications of porous asphalt in Malaysia took place in the 1990's on the JKR roads. However, the performance of the material has not been encouraging, primarily due to ravelling and clogging. Initial porous asphalt experience in Japan was imported from Europe in 1987 and encountered similar problems. However, these problems have been successfully resolved by using a high viscosity modified asphalt developed in Japan. Now, porous asphalt has been popular in Japan. This paper presents the design concepts of the technology. The aggregate design incorporates a gap between 2.36mm and 4.75mm to increase the percentage of connected air voids; hence improved permeability and better resistance to clogging. Bonding between aggregate particles is significantly enhanced using TPS modifier that results in approximately binder grade comparable to PG82. The modified binder is characterized by its high mechanical properties, good anti-stripping and anti-aging properties. The results of the tri-axial compression test are introduced to explain the durability of the porous asphalt. In view of the superior laboratory mixture properties, a field trial was conducted on the North-SouthExpressway. The monitoring results after sixmonths in service demonstrate excellent condition. This paper also deliberates on the successful applications of Japanese technology in Asia.