South Carolina Department of Transportation builds on more than three decades of experience using recycled tire rubber in asphalt to improve pavement durability and sustainability.
South Carolina is continuing to build on more than three decades of experience incorporating recycled tire rubber into asphalt, with the state’s Department of Transportation (SCDOT) using rubberized asphalt technologies to improve pavement performance while supporting sustainable material use.
The agency’s long-running work has focused on finding effective ways to use scrap tire rubber in road construction while delivering durable pavement and improving the overall performance of asphalt systems.
Combining Pavement Performance with Sustainability
According to Dr. Kimberly “Kimmie” Lyons of SCDOT, the department’s adoption of rubberized asphalt has been driven by several objectives, including better pavement performance, sustainability and long-term cost efficiency.
Adding recycled tire rubber to asphalt can improve resistance to common pavement problems such as cracking and rutting. The technology can also help reduce roadway noise and extend the useful life of pavement, while providing a productive application for recycled tire material.
Research Partnership with Clemson University
Lyons’ involvement with rubberized asphalt began during her graduate studies at Clemson University, where she researched rubberized Open Graded Friction Course (OGFC) for SCDOT.
That academic work helped establish a foundation for understanding the behaviour and potential applications of rubber-modified asphalt. The continuing relationship between Clemson University and SCDOT has also contributed to research and technical knowledge surrounding the use of recycled tire rubber in asphalt mixtures across South Carolina.
A Programme Dating Back to 1991
SCDOT’s work with crumb tire rubber in asphalt mixtures began in 1991. Over the years, the department developed and refined its specifications, including provisions for adding ground tire rubber (GTR) to liquid asphalt at supplier terminals through a controlled wet-process system.
When correctly incorporated, this approach can improve the performance of conventional asphalt binders, bringing their characteristics closer to those associated with polymer-modified asphalt.
Although the wet process continues to be permitted, its adoption among contractors has remained relatively limited. Material handling requirements, together with additional equipment maintenance, can create operational challenges.
SCDOT’s experience has shown that factors such as accurate mix design, appropriate temperature management and contractor expertise play an important role in achieving reliable results.
Current Rubberized Asphalt Technologies
Today, SCDOT allows both dry-process and wet-process rubberized asphalt technologies.
The department’s current applications include dense-graded asphalt mixtures manufactured using the dry process. Rubber is also used as a durability-enhancing additive in stone matrix asphalt (SMA) mixtures.
Another application is the stress-absorbing membrane interlayer (SAMI), which can be installed before asphalt overlays to help limit reflective cracking.
Together, these technologies are intended to improve pavement durability, strengthen resistance to cracking and rutting, and increase pavement service life.
Benefits of Collaboration
SCDOT has also drawn on the experience of other transportation agencies as it has developed its rubberized asphalt programme.
The Georgia Department of Transportation has been particularly valuable as a source of practical experience. By examining Georgia’s performance information, specifications and implementation lessons, SCDOT was able to gain additional insight and reduce some of the risks associated with adopting rubberized asphalt technologies.
Addressing Implementation Challenges
One of the challenges facing wider adoption has been limited contractor experience with rubberized asphalt. Questions around mix consistency and the methods used to introduce rubber into asphalt mixtures have also required attention.
SCDOT has responded through several measures, including contractor training, detailed specifications, pilot projects and continued communication between contractors and department personnel.
These initiatives have helped contractors become more familiar with the technology while improving consistency and confidence during implementation.
Building on Long-Term Experience
South Carolina’s experience demonstrates how recycled tire rubber can become a practical component of pavement programmes when its use is supported by research, technical specifications, contractor involvement and sustained implementation efforts.
From its initial wet-process evaluations in the early 1990s to current applications involving dry-process mixtures, SMA and SAMI treatments, SCDOT continues to develop its approach to recycled tire rubber in asphalt.
The programme highlights the potential for recycled tire rubber to support both road performance and sustainability, creating a useful pathway for scrap tires while contributing to more durable infrastructure.
Key Takeaways
- SCDOT has been evaluating and using recycled tire rubber in asphalt since 1991.
- Rubberized asphalt can improve resistance to cracking and rutting and may extend pavement service life.
- Both wet-process and dry-process rubberized asphalt technologies are permitted by SCDOT.
- Current applications include dense-graded asphalt mixtures, SMA and SAMI treatments.
- Proper mix design, temperature management and contractor experience are important for consistent performance.
- Research collaboration with Clemson University has contributed to technical knowledge in the field.
- Experience from the Georgia Department of Transportation has also helped inform SCDOT’s approach.
- Contractor training, pilot projects and clear specifications have supported wider implementation.
-
Recycled tire rubber provides a beneficial use for scrap tires while contributing to sustainable road construction.