Presentation by Nate Gauff, CalRecycle, on the agency's efforts to promote the use of recycled tires 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. CalRecycle's Support
of Rubberized Pavement
Nate Gauff
CalRecycle
April 18, 2023

2. What Does CalRecycle Do?
❑ Manage handling, disposal and recycling of non-hazardous
solid waste
❑ Paper, plastics, glass, metal, organics/yard waste
❑ Used oil, mattresses, paint, household hazardous waste, TIRES

3. Tire Program
❑ Created via legislation in 1989
❑ Identified RAC & TDF uses as best initial diversion efforts - 1992
❑ First major recycling investment was with Caltrans – 1992
❑ First tire recycling grant program started – 1992
❑ First RAC Tech Assistance contract w/ Los Angeles County – 1997
❑ Major Tire Stockpile Fires – 1998 and 1999
❑ Major Legislative Funding Increase – 2000

4. Tire Program
❑ Dedicated RAC Grant Program started – 2002
❑ First Consultant RAC Technical Assistance Contract – 2004
❑ Legislative mandate for RAC use by Caltrans – 2005
❑ RAC promotion and outreach campaign – 2007
❑ RAC technical research contracts UCPRC, CSU-Chico, Local
Governments - 2007-Present

5. The Beginning
Use Numbers (M) 1990
Total Tires Generated 27.0
TDF (MELP & Cement Kilns) 4.0
Retreaded 2.3
Exports 1.3
Reused 1.0
Other Recycling (RAC, TDP) 0.6

6. Use Numbers (M) 2021 2010 2000 1990
Total Tires Generated 55 41.1 31.6 27
TDF 4.8 8.4 5.2 4.0
Retreaded 5.5 3.6 2.4 2.3
Exports 4.4 1.8 1.9 1.3
Reused 4.3 2.0 3.6 1.0
Other (RAC/TDA/TDP) 9.6 10.5 13.0 0.6

7. ❑ The use of tire rubber in rubberized pavement applications has
been a diversion strategy supported by the CalRecycle since
the very beginning of the Tire Program.
❑ The use of rubberized pavement by State and Local Agencies
currently diverts about seven million waste tires per year from
landfill disposal
❑ Over the past 25 years of the Tire program use of rubberized
pavement has diverted an estimated 80+ million waste tires

8. Overview of Support
❑ Caltrans
❑ Research Contracts
❑ Local Government
▪ Technology Transfer
▪ Grants

9. Caltrans-CalRecycle Collaborations
❑ Technical Research Interagency Agreements
▪ 1992-Lab Test Equip
▪ 2003-RAC State of the Art (AR Usage Guide)
❑ Field Evaluated Research
▪ 1993 Maintenance Strategies – Hwy 16
▪ 2002 Overlay Comparison – Hwy 33
❑ PG+X
▪ 2015,2018 Laboratory Investigations

10. Research Contracts
▪ Use research contracts to fill in gaps in
knowledge base, determine feasibility of
technology, investigate new processes and
materials
▪ Partner with entities that have a proven
expertise with rubberized pavement projects
and/or research. Caltrans, UCPRC, CSU-Chico,
LA County

11. Research Contracts
❑ Terminal Blend Chip Seal Demonstration Project
❑ Reclaimed Asphalt Pavement (RAP) in Chip Seal
Demonstration Project
❑ Life Cycle Cost Analysis (LCCA) for RAC materials
❑ Warm Mix Asphalt Performance Evaluations
❑ RAC Hot-Mix Performance Model Development
❑ RAC Chip Seal Performance Model Development
❑ RAP in RAC and Rubberized RAP in Hot Mix

12. Current Research Contracts
Use of Small Amounts of Rubber in HMA
▪ Multi-Year research effort to incorporate 5-10%
crumb rubber in all asphalt binder
▪ Performed laboratory evaluation of binder impacts
for several different production processes
▪ Will test and evaluate several materials from field
pilot projects
▪ Could potentially double the use of crumb rubber in
asphalt

13. Current Research Contracts
Reclaimed Asphalt Pavement (RAP) in RAC
▪ First study (2014-16) looked at use of RAP in
context of binder replacement
▪ Second study looked at use of RAP in the
context of aggregate replacement
▪ Field demonstration evaluations for RHMA-G

14. Current Research Contracts
Pelletized Rubber Demonstration Project
▪ Testing three different pelletized rubber
additives into dense graded asphalt mixes
▪ Partnership with Stanislaus County and CSU-
Chico
▪ Side by side field comparison of the materials

15. Local Government Support
Technology Transfer
❑ Provided training for over half of the local governments in
California
❑ CalRecycle partnered with Los Angeles County DPW in 1997 to
create the first RAC Technology Center
❑ The center was created to promote the use of RAC by local
governments via peer to peer
❑ The center provided RAC technology transfer and technical
assistance to local government agencies
❑ Added a Northern Center using Sacramento County staff in
2000

16. Local Government Support
Technology Transfer
❑ Transferred Effort to Engineering Consultant firms in 2004 –
MACTEC (AMEC), Jacobs Engineering Group,
Quincy Engineering, Interwest Consulting
❑ Direct technical support of our expanding RAC grant programs
❑ Engineering Evaluation and design assistance
❑ Increased field support of grantees
❑ Technical Investigations

17. Local Government Support
Grants
❑ Dedicated RAC grants since 2002 – SB1346 Rebate
❑ Expanded the grant program with Full Differential Incentive
Grants – 2005; Rubber Chip Seal Grants - 2007
❑ Current Grant Reimbursement is $4, $7 or $10/ton in
Southern California and $8, $14 or $20/ton in Northern
California
❑ Currently about $4M allocated per year
❑ Half of all tire recycling grants given by CalRecycle over
the last 30 years have gone to rubberized pavement
❑ $115M awarded in RAC grants

18. Why CalRecycle Continues to Support Rubberized Pavement
❑ Largest recycling use of waste tire rubber
❑ Demonstrated superior performance of RAC over
conventional AC. Long-lasting durability; lower
maintenance.
❑ Shown to be a cost beneficial resurfacing option over
conventional AC

19. Final Thoughts
❑ You need funding to do this work
❑ You need the best and brightest to assist in
research
❑ You need innovators willing to take a chance
on new technology/methodology

20. Questions?