The U.S. Tire Manufacturers Association (USTMA), in partnership with the University of Missouri and The Ray, a nonprofit proving ground for sustainable transportation technologies, published this July a state of knowledge report that assessed existing research on the economic, performance and environmental benefits of using ground tire rubber (GTR) in asphalt. The report finds that rubber modified asphalt is a resilient pavement solution to rebuild America’s roadways and a promising sustainable and circular end-of-life market for scrap tires. The report also provides recommendations for additional research to ensure a comprehensive understanding of the technology’s impact.

Developing sustainable end-use markets for the 260 million scrap tires generated annually in the U.S. is a top industry priority, according to USTMA. Rubber modified asphalt, which incorporates ground tire rubber made from scrap tires into asphalt, provides demonstrated economic, performance and environmental benefits. Compared to traditional asphalt, rubber modified asphalt provides cost savings over the life of the asphalt, extends pavement life, and reduces noise, CO2 emissions and tire and road wear particles. Rubber modified asphalt also leads to lower rolling resistance, which helps improve fuel economy.

Dr. Bill Buttlar, director of the Missouri Center for Transportation Innovation and the report’s lead researcher, worked to answer a critical question: Can rubber modified asphalt help eliminate scrap tire stockpiles in the U.S., boost pavement sustainability and longevity, and allow more miles of roads to be repaired?

“This research provides those who make infrastructure decisions – road operators, state and federal regulators and legislators, pavement and road construction contractors and researchers – with important information on the effectiveness and environmental impact of rubber modified asphalt,” said Dr. Buttlar. “It outlines why states should review and expand asphalt specifications to incorporate this proven alternative. We should continue to research rubber modified asphalt to better understand the complete picture of this pavement’s environmental impacts and benefits.”

“The report demonstrates the value of upcycling tires into higher performing roads that will help states save money over the life of the roadway and make our roads quieter,” said Allie Kelly, executive director of The Ray. “Our work with USTMA and the University of Missouri demonstrates how we can work together to find safe and sustainable solutions. The opportunity to scale and expand the utilization of rubber-modified asphalt across all 50 states has arrived, with Congressional action on transportation and infrastructure funding, and the publishing of this inventory of the best research and analysis of RMA.”

“The University of Missouri’s research review proves that rubber modified asphalt is a strong and viable application for advancing the sustainability and circularity of scrap tires,” said Anne Forristall Luke, President and CEO of USTMA. “To help grow this market safely and responsibly, USTMA supports infrastructure legislation to increase opportunities for university and government research, regional innovation hubs for rubber modified asphalt, and federal procurement of rubber modified asphalt. We also advocate that states and municipal communities should consider expanding asphalt specifications to include rubber modified asphalt as a possible pavement choice.”

Also of importance, the state of knowledge report identified data gaps that should be addressed to better inform modern pavement design software programs, including the need for additional research on the life cycle impact of rubber modified asphalt and its properties and characteristics.

The research was peer-reviewed by a technical advisory panel of regulators, researchers and scientists that provided support, insights and feedback. The study reviewed more than 300 scholarly articles and reports and surveyed 26 state highway agencies to identify data gaps in knowledge and barriers to more widespread adoption of rubber modified asphalt nationwide.

About the U.S. Tire Manufacturers Association

The U.S. Tire Manufacturers Association is the national trade association for tire manufacturers that produce tires in the U.S. The association’s 13 member companies operate 57 tire-related manufacturing facilities in 17 states and generate more than $27 billion in annual sales. The industry directly supports more than a quarter million U.S. jobs – totaling almost $20 billion in wages. USTMA advances a sustainable tire manufacturing industry through thought leadership and a commitment to science‐based public policy advocacy. The association’s member company tires make mobility possible. USTMA members are committed to continuous improvement of the performance of their products, worker and consumer safety and environmental stewardship. 

About the Missouri Center for Transportation Innovation

The Missouri Center for Transportation Innovation is a powerful network of partners including the four University of Missouri campuses, the Missouri Department of Transportation (MoDOT), the Federal Highway Administration and other agencies and industrial partners. These relationships provide access to cutting-edge resources such as state labs, field experiments, advanced computing, simulators and virtual reality.

MCTI began as a collaboration between the University of Missouri System and MoDOT to establish Missouri as a showcase and a clearinghouse for safe, accessible, sustainable and resilient transportation.

About The Ray

The Ray is a proving ground for the evolving ideas and technologies that will transform the transportation infrastructure of the future with the mission to build a zero carbon, zero waste, zero death highway system. It begins with the 18-mile stretch of interstate named in memory of Ray C. Anderson (1934-2011), a Georgia native who became a captain of industry and was recognized as a leader in green business when he challenged his company, Interface, Inc., to pursue zero environmental footprint. Chaired by Ray’s daughter Harriet Langford, The Ray is an epiphany of the Ray C. Anderson Foundation.

Press release by USTMA.