Development of new mix design method for asphalt mixtures containing RAP and rejuvenators

Recycled materials, such as reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS), have been widely used in asphalt paving industry, and the trend seems to use more and more, because they can save taxpayer dollars, preserve energy and protect the environment. However, these recycled materials are often highly aged and cause potential durability issue for asphaltic mixtures. Rejuvenators have been recently receiving attention from the pavement research community because they can improve the engineering properties of asphalt mixtures containing high content recycled materials. This study presents a new mix design method developed for asphalt mixtures containing RAP and rejuvenators which were constructed in the field test sections. A series of laboratory tests were conducted based on the step-by-step design procedure developed. In order to properly improve the performance of the mixtures using rejuvenators, asphalt binder samples blended with rejuvenators were tested, and a kind of balanced mix design method was applied to determine the optimum asphalt content and optimum rejuvenator content. Laboratory test resulting indicated that careful selection of the rejuvenator dosage would be required for balanced cracking and rutting performance of asphalt mixtures.