This synthesis will be of interest to pavement designers, construction engineers, and others interested in economical methods for reconstructing or rehabilitating bituminous pavements. Information is provided on the processes and procedures used by a number of states to recycle asphalt pavements in place without application of heat. Since 1975 a growing number of state highway agencies have reconstructed or rehabilitated asphalt pavements by recycling the old pavement in place. This report of the Transportation Research Board describes the processes used for cold in-place recycling, including construction procedures, mix designs, mixture properties, performance, and specifications.

A comprehensive lab and field investigation was carried out to evaluate the performance of recycled asphalt mixtures in Missouri by researchers at the University of Missouri-Columbia, in collaboration with the Missouri Department of Transportation and the Midwest Transportation Center. Sixteen field sections were evaluated, including a number of sections from the recent Long-Term Pavement Performance (LTPP), Special Pavement Sections (SPS-10) project in Osage, Beach, MO, which was constructed in 2016. Binder testing and mix performance tests were carried out on field cores and laboratory compacted specimens. Based on the findings of the study, the following conclusions were drawn: (1) Missouri’s practices for the responsible and effective use of recycled materials is sound, and continues to improve over time - recent mix designs demonstrate more appropriate balancing between recycled material levels and virgin binder selection, resulting in better performance tests results when compared to older recycled mix designs; (2) Opportunities exist for further improving recycled mix design methods and recycling optimization in Missouri, including (a) Moving to higher ABR levels, by implementing mixture performance tests (balanced mix design); (b) Increasing the use of recycled ground tire rubber (GTR) in Missouri mixes, by using balanced mix design to certify mixes using new, more economical GTR recycling methods, and; (c) Researching the use of recycled materials in stone-mastic-asphalt (SMA) designs. It is recommended to further evaluate and fine-tune mix performance tests for use in balanced mix design, which is particularly important for modern, heterogeneous recycled mixes.

Research and Application of Hot In-Place Recycling Technology for Asphalt Pavement is the first comprehensive book on the topic that presents over two decades of theoretical and practical experience gained in China. The book gives comprehensive coverage of HIPR, including pavement evaluation, distress analysis, mix design, processes and equipment selection, implementation and acceptance criteria. In eight chapters, this book covers HIPR from theoretical and practical viewpoints, and provides detailed case-studies based on real-world experience. This book includes everything engineers need to apply HIPR to improve sustainability and reduce disruption during the maintenance and repair of asphalt. Presents, for the first time in English, decades of experience and research on Hot in-Place Recycling Technology (HIPR) for asphalt pavements Considers all aspects of HIPR, giving engineers all they need to use the technique for road maintenance and repair Details how HIPR drastically improves the sustainability of asphalt and reduces disruption to traffic during repair and maintenance work Includes detailed case studies from thirty years of HIPR in China, giving context and practical know-how

This report describes a project in which approximately 6,200 tons (5,630 Mg) of asphaltic concrete were recycled through a conventional asphalt batch plant. During the construction of the project, a buildup of asphalt-coated fines occurred in the dryer and the dust collector. The buildup is thought to have been associated with the fineness and/or the high asphalt content of the recycled mix. To solve the problem, a change was made in the recycling process. The project was completed using a heat transfer method with mix proportions as high as 50% recycled material added to 50% virgin aggregate.