Israel Eduardo RENDON VILLALON

Study on Durability of Asphalt Stabilized Base Course Material Containing RAP in Japanese Expressways 

Osamu TAKAHASHI, Takeshi NAKAMURA

The study of reclaimed asphalt pavement (RAP) has generally been focused on the applications of this material in wearing courses of pavements. 
Conservation of natural resources and reduced demand of virgin bitumen resulting in cost reduction are examples of the benefits obtained from 
reusing the pavement surface. It is not surprising that these benefits are a motivation for further action, with highway transportation 
agencies and private companies now looking for ways to utilize RAP as a component material in the base course. 
In the Niigata region, NEXCO, a Japanese operator of expressways in Japan, is expanding the number of lanes of an expressway, using a stabilized
base course mixture composed of 15% of RAP. This is the first time the company has opted to use RAP with such purpose in an expressway. 
The present case study is the first to explore whether the stabilized base course mixture containing 15% of RAP can withstand the harsh winter 
conditions of the Niigata region, and how the durability of the mixture compares to others designed with 20%, 25% and 40% of RAP. This research 
also intended to find a maximum acceptable amount of RAP that can be used without compromising the durability of the base course. Moisture 
susceptibility and cracking potential at low temperature of all compacted specimens were examined by means of the Modified Lottman Test and the 
Three Point Bending test using the same materials found in the construction site of the expressway.Results show that the virgin mixture and those 
containing 15%, 20% and 25% of RAP are not sensitive to the attack of moisture. Increasing the RAP content to 40% caused the stabilized base course
to be more susceptible to moisture damage, risking the structure to fail. Moreover, the fracture resistance at low temperature of the 15% RAP 
mixture was higher than that of the 40% RAP mixture. Therefore, the stabilized base course mixture composed of 15% of RAP, currently being used in 
the Japanese expressway here mentioned, is expected to have satisfactory moisture and fracture resistance at low temperature in the field.