Asphalt Pavement Magazine - November/December 2015 - (Page 24)

Investigating the keys to Japanese RAP Success Excerpts from "Japanese RAP Practices 2014 Scan Tour: Lessons Learned" By Randy West, Ph.D., P.E., and Audrey Copeland, Ph.D. O n average, 47 percent reclaimed asphalt pavement (RAP) is used in Japan's asphalt pavements. In the United States, the average amount of RAP used in asphalt mixtures is about 20 percent. Since 2007, the U.S. pavement industry has made a concerted effort to increase the amount of RAP used in asphalt pavements due to increased cost of virgin materials and a desire to emphasize sustainable, environmentally friendly practices. Based on annual industry and highway agency surveys, there appears to be an upper limit on the average amount of RAP in asphalt mixtures of about 20 percent; however, these same surveys have identified that the majority of state department of transportation (DOT) specifications and standards will allow up to 30 percent RAP on average. The National Asphalt Pavement Association (NAPA) and Federal Highway Administration (FHWA) promote the increased use of RAP in asphalt pavements. They wanted to learn how Japan has achieved a national average of 47 percent RAP in asphalt mixtures, the quality achieved, and the best practices applied. An industry scanning tour of Japan was planned and took place in December 2014 to learn about Japan's use of high RAP. The scan trip also focused on construction operations and practices used in Japan. Japanese contractors and road owners follow a simple mix design and materials testing process with a focus on performance. One of the most striking differences between Japan and the U.S. is the 24 * View past issues online at United States' use of the Superpave tests and materials specifications. Japanese contractors and officials stated that the Superpave system is complicated and testing is expensive. In Japan, there is well-established trust among the government and industry; however, on government projects contractors must get permission to use RAP. The quality of Japan's pavements During a tour of a RAP plant, the U.S. tour group was shown small piles of virgin asphalt mix, and mixtures with 45 and 60 percent RAP.

Table of Contents for the Digital Edition of Asphalt Pavement Magazine - November/December 2015

President’s Perspective
Industry News
Winning the Race Track Challenge
Investigating the Keys to Japanese RAP Success
A Fresh Perspective on Safety
Traffic Management and the Work Zone
2016 Annual Meeting Preview
Calendar of Events
Index of Advertisers/

Asphalt Pavement Magazine - November/December 2015