Field Demonstration of Post-Consumer Waste Plastics and Ground Tire Rubber in Columbia, Missouri

Research has shown that asphalt pavements can serve as a destination for some of the major streams of waste materials around the globe, such as scrap tires and plastics. Heightened restrictions imposed by China in terms of waste stream contamination in 2018 has catalyzed research on incorporating post-consumer recycled (PCR) plastics into asphalt pavements. On the other hand, Ground tire rubber (GTR) from scrap tires have been used in asphalt pavements since the 1960s, but has not achieved its full potential in terms of market adoption. A field demonstration project is underway in Columbia, MO, to evaluate the incorporation of modern recycled plastic and GTR in asphalt mixtures. The project focused on dry-process modification which requires minimal alterations to an existing asphalt plant and allows a higher amount of the recyclates to be added. The project was designed to assist in Missouri DOT’s early roll-out of Balanced Mix Design (BMD) specifications. Among the strategies investigated, it was found that a softer virgin binder grade led to the best improvement in BMD cracking test scores. From a production and construction point of view, the operations went smoothly and closely mirrored the equipment, procedures and results observed early in the project during the control mixture production and laydown stage. After the first two winters, a moderate amount of reflective cracking was noted in all test sections and in the control section. The results of the study suggest the viability of dry-process, GTR and PCR plastic as a greener alternative to binders modified with virgin polymers and/or chemical treatments. Future studies will be needed to examine additional PCR plastic streams, especially more highly mixed streams.

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Report number: cmr 23-009
Published: April 2023

Project number: TR202125
Authors: William G. Buttlar, Punyaslok Rath, Jim Meister, Hamed Majidifard, Patrick Beckemeyer, Nandita Gettu, and Helmut Leodarta

Performing organization: Missouri Center for Transportation Innovation