Dr. Dave Jones of the University of California Pavement Research Center provides an academic perspective of in-place recycling in a presentation delivered during the CalAPA Spring Asphalt Pavement Conference March 7-8, 2024 in Ontario, Calif.

1. David Jones, PhD
University of California Pavement Research Center
COLD RECYCLING OF ASPHALT PAVEMENTS:
RESEARCH TO SUPPORT IMPLEMENTATION
CalAPA Spring Asphalt Pavement Conference
Ontario CA, March 7 - 8, 2024

2. Outline
▪ Introduction
▪ Research Roadmap
▪ Focus areas
▪ Challenges

3. Research Roadmap
▪ Vision:
 Recycle first
▪ Phased approach to support
implementation of CR in California
 Phase 1: FDR-FA
 Phase 2: FDR (including APT)
 Phase 3: PDR and CCPR (including APT)
 Phase 4: Gaps in the knowledge limiting
implementation

4. Focus Areas
▪ Guidance
 CR guideline regularly updated
 Site investigation guide
▪ Pavement design (CalME)
 Laboratory, APT, and long-term
performance data used to update/
improve models
▪ Mix design and QC/QA tests
 Standardized CR mix design procedures
in CT format
▪ Specification language
 Data-supported standardization in
Section 30

5. Recently Completed Research
▪ Mix design
 Questioned everything
 Standardized mix design and QC/QA tests
 CCPR stockpiling
▪ Pilot studies
 Supplemental fines
 Recycling train comparisons
 Emulsified and foamed asphalt comparisons
 Cold central plant recycling
▪ Pavement design
 Updated mechanistic models for CR materials
 Inverted pavements for high traffic road rehab
▪ QC/QA procedures
 Rapid in situ test to assess raveling and shear
properties (for AASHTO)

6. Challenges
▪ Nature of cold recycling
 Variability of materials and pavement structures
 Design and construction

7. Challenges
▪ Fitting CR into agency "remove
and replace" decision processes/
policies and funding buckets
 CR currently cannot be used
effectively (cost and sustainability) in
this approach

8. Some Example Differences
▪ Remove and replace
layer(s)
▪ Mostly new materials
▪ Large increase in cost and
complexity with depth
▪ Project duration increases
with depth
▪ Construction traffic
increases with depth
▪ Often a holding action
▪ Recycle to bottom of
distress
▪ Mostly in-place materials
▪ Cost limited to recycling
agent
▪ Same project duration
▪ Construction traffic limited
to recycle agent + new AC
▪ "New" road

9. Summary
▪ Cold recycling (PDR, FDR, CCPR) is a
proven strategy, with hundreds of
publications, but limited national
implementation
 We have all the ingredients, but no cake
 Many reasons
▪ Research needs to move beyond
proving how good CR is to helping
agencies implement it effectively
▪ There is a recycling strategy for most
pavement problems

10. Thank-you!
djjones@ucdavis.edu
www.ucprc.ucdavis.edu