Strategies for Incorporating Higher Recycled Asphalt Pavement Percentages Review of Implementation Trials in Northeast States

Because there is a greater emphasis on promoting sustainable materials within transportation infrastructure, state agencies in the U.S. Northeast are investigating different strategies that will enable the use of higher percentages of recycled asphalt pavement (RAP) while not sacrificing the performance of the asphalt pavement. In particular, most state agencies in the Northeast are concerned with the fatigue and thermal cracking performance, as well as the general workability and handling of the higher-RAP-content asphalt mixtures when greater percentages are used. In conjunction with the Transportation Pooled Fund study TPF 5(230), Evaluation of Plant-Produced High-Percentage RAP Mixtures in the Northeast, three potential strategies were evaluated for incorporating higher RAP contents: using a softer asphalt binder grade to offset the stiff RAP asphalt binder, limiting the amount of RAP binder credited to the total asphalt content of the asphalt mixture, and using a performance-based specification that the high-RAP content mixture must meet for acceptance. The findings of the strategies through plant-produced mixtures, as well as case studies evaluated in detail through laboratory test procedures and analysis, are summarized. The project trials and results shown will, it is hoped, provide guidance to other agencies looking to increase the percentage of RAP used in their asphalt mixtures.