Presentation by Liberty Tire on the use of recycled rubber in asphalt pavements. Delivered at the California Asphalt Pavement Association "Where the Rubber Meets the Road" asphalt rubber educational workshop April 18, 2023 in Sacramento.

1. An Innovative, Pre-Treated Rubber
Solution for the Asphalt Industry

2. About Liberty Tire

3. 3
Next Generation Dry Process – What is it?
• Old dry process worked occasionally, but too many variables caused
problems.
• New systems have:
» Beneficial additives with rubber = Engineered Crumb Rubber Systems
» Lower rubber content to match other modified asphalt systems ~10% by
weight of binder
» Finer rubber gradation ~30 mesh to ensure full absorption of binder into
rubber before placement
» Can be used with standard mixes without changes
» Works well with RAP, promotes increase in RAP contents

4. ▪ SmartMIX™ pre-treated recycled tire
rubber (RTR) is a dry, free-flowing rubber
for direct addition to asphalt mixtures
at the mix plant.
▪ Its use is controlled with on/off switch at
the mix plant, meaning that there are
never any wasted materials.
▪ SmartMIX™ is a pavement properties
enhancer, NOT a binder modifier.
▪ Use of SmartMIX™ will yield a pavement
competitive to one made with polymer
modified binders with similar or better
properties at a lower cost.
SmartMIX™ is patented technology for
asphalt mix formulations.
What is SmartMIX™?

5. SmartMIX™ is easily added at the mix plant.

6. Lake Lansing Project Image from May 2021
• Darker color in SmartMIX™
due to tire rubber and
carbon black
• Darker potentially due to
higher maltene content
from extender oil
• Maltenes are lost as
asphalt ages, SmartMIX™
adds Maltenes
Full depth reconstruction 6.5”
Control Mix

7. Lake Lansing Road
Pilot Validation of
SmartMIX™
Similar mixes placed in
2015, with and w/o
SmartMIX™
Photos from
May 2021
Mixes contain
33% RAP
Some Sections Full
Depth

8. IDEAL-CT Results
17
• Control Mix –AC
=5.6%; CTIndex=54
• Selected AC for
SmartMix =5.6%
• 12% SmartMIX
added by weight of
total binder
• SmartMIX
CTIndex=78

9. Selected for 2021-23 NCAT Test Track Cycle
•46 Sections On the Track
•5 Trucks Simultaneously Driven
•156,995 lb Average Truck Weight in the Fleet
•1.7 Miles Test Track Length
•10,000,000 ESALs Applied in Research Cycle

10. Selected for 2022 MnROAD Test Track

11. Project Map

12. is Easy To Use
• Standard, Superpave, and Balanced Mix Design Used
• No Changes to Existing Mix Design, other than adding SmartMIX™
• No extended mixing times or elevated temps required
• No impact on plant Permits
• No excessive odors or fumes
• SmartMIX™ helps reduce stiffness and brittleness from RAP (use more
RAP)
• Use Balanced Mix Design to determine Maximum RAP content
• SmartMIX™ makes rubberized mixtures easy to roll and compact

13. For more information, contact:
Mr. Doug Carlson
Vice President, Asphalt Products
dcarlson@libertytire.com
(602) 751-6039
Liberty Tire Recycling
600 River Ave, 3rd Floor
Pittsburgh, PA 15212
www.libertytire.com