The document discusses different methods for adding recycled tire rubber to asphalt, including the traditional wet process, dry process, and Rapid Digestion Process (RDP). The RDP allows for a higher percentage of tire rubber (40-50%) to be added by blending shredded or mulched rubber into the asphalt before adding aggregate. RDP mixtures have over 98% solubility and compatibility between the rubber and asphalt. RDP provides benefits like improved cracking resistance, fatigue resistance, and compatibility with recycled asphalt materials.

1. RDP
Rapid Digestion Process

2. Recycled Rubber
▪ From Truck & Auto Tires
▪ Belts (Fiber, Steel) Removal
▪ Grinding to different mesh sizes
Crumb Tire Rubber

3. Tire Rubber
Modified
Asphalt
Dry Process
• Adding 30-40 Mesh size to finished binder after adding
aggregate
• Tire Rubber addition in range of 3-7%
Traditional Wet Process
• Adding 30-40 Mesh size blended with asphalt before
adding aggregate
• Tire Rubber addition in range of 18-25%
Sigmabond
• Rapid Digestion Process
• Adding Mesh or Mulch size blended with asphalt before
adding aggregate
• Tire rubber addition in range of 40-50%

4. Sigmabond
Modified
Asphalt
Rapid Digestion Process
Adding Mesh or Mulch size blended with asphalt before adding aggregate
Tire rubber addition in range of 40-50%
Solubility > 98.00%
No TR Separation & Great compatibility
Stable Viscosity with increasing Sigmabond
Improving m-Value with increasing Sigmabond
Improved ∆Tc (Thermal Cracking) with Sigmabond
Reduce PAV DSR with increased Sigmabond
Superior Black Space Performance with Sigmabond

5. TIRE RUBBER CONTENT EVALUATIONS IN
RDP
(RAPID DIGESTION PROCESS)
PG64-22 Vs. PG64-22R
PG64-22 Vs. PG64-22R (RDP Base)

7. Other Benefit
• Storage Stability!
• Consistent Laydown, Breakdown, and Compaction
• Ability to Improve binder Cracking resistance!
• More Prolong resistance to Thermal Cracking
• Reduce Fatigue Cracking!
• RAP & RAS Compatibility
• Active project
• UCA, Davis
• Longer Life!

8. Thank you