At the California Asphalt Pavement Association (CalAPA) Spring “Technical Tune-Up” Educational Workshop held April 5, 2022 in Brea, a presentation titled, "Cold in-place Recycling (CIR) and Cold Central Plant Recycling (CCPR) in Sustainable Pavement Rehabilitation & Reconstruction" was delivered by Michael Concannon, P.E., Engineering Manager, Pavement Recycling Systems, and Kevin Donnelly, APM, Director - Southern Region, Western Emulsions. City and County agencies in California are utilizing Sustainable Pavement Engineering processes, such as Cold Central Plant Recycling (CCPR) and Cold In-place Recycling (CIR) of asphalt to stretch their roadway budgets, achieve their sustainability goals, and reduce construction-related community impacts. This tech tune-up presents the latest updates on Public Works Specifications for these processes, Mix Design requirements, and highlights a few recently completed projects.

1. Michael Concannon, PE
Engineering Manager
Pavement Recycling Systems, Inc.
Update on Cold Recycling
in California
CalAPA Tech Tune-Up
April 5, 2022
Kevin Donnelly, APM
Director of Sales, Southern Region
Western Emulsions Inc.

2. Current Cold Recycling
Applications in CA
◼ Cold In-place Recycling with Emulsified Asphalt (CIR-EA)
◼ Cold Central Plant Recycling with Emulsified Asphalt (CCPR-EA)
◼ Cold In-place Recycling with Foamed Asphalt (CIR-FA)
◼ Cold Central Plant Recycling with Foamed Asphalt (CCPR-FA)

3. Bituminous Recycling Agents
Asphalt Foam Recycling Agent
Mastic technology - Typically fines 8% to 20%
Proven not necessary in CIR (<5% fines)
HOWEVER finer aggregate (#30
Passing) is necessary
Emulsified Asphalt Recycling Agent
Coating/Binding Technology
Concern is that with foamed asphalt, commonly too
much cement is used in order to pass lab testing.
Should maintain the 2.5:1 ratio of binder to cement.

4. Lab Coating
Emulsified Asphalt
Foamed Asphalt
Same aggregate; same residual asphalt content

5. Foamed Asphalt
Emulsified Asphalt
Field Coating

6. Caltrans Cold Recycling
Specifications
◼ Partial Depth Recycling (PDR) nSSP
◼ Cold Central Plant Recycling nSSP
◼ California Test 315 – CIR (PDR) Mix Design Specification
◼ California Test 316 – CCPR Mix Design Specification

7. CALTRANS CT 315 AND CT 316
Emulsified Asphalt
Marshal Stability
@ 104 Deg. F.
Foamed Asphalt
ITS @ 77 Deg. F.

8. CALTRANS CT 315 AND CT 316
Most recent changes
have transitioned
from LP-8 to CT 315
(CIR) and CT 316
(CCPR)
Performance Standard
ITS (Foamed Asphalt)
Marshall (Emulsion)
Reporting required for
both

9. Raveling Test
Emulsified Asphalt
Proper CIR Inadequate CIR
Click to run video clips
Foamed Asphalt Will Not Pass

10. All based on break-over
curves established in
the field during
construction
Depths greater than 4”
– California Test 216
(Direct Transmission)
Relative Compaction
Depths less than 4” –
California Test 375
(Backscatter)

11. Multi Unit Trains
Emulsified Asphalt
Recycling Agent
Equipment Misconception in CIR
Wirtgen 380
Asphalt Foam
Recycling Agent
Wrong! Both
Equipment Can
Do Either

12. Caltrans CIR History
◼ In California
• From 2003 to 2016, CIR was 100% emulsified
asphalt recycling agent with generally very positive
results
• 2015 - CIR Subtask Group on Foam completed
NSSP and mix design lab procedure for CIR-FA, and
two pilot projects were performed with generally
positive results
• 2020 - CIR (now PDR) Subtask Group combined
PDR-EA and PDR-FA specifications and mix design
procedures, allow for Contractor choice of emulsion
or foamed asphalt

13. Caltrans CIR History
◼ In California
• Several projects completed with new CIR
specifications
• 3 pilot projects completed last year for evaluation
of various specification details and options
• Direct comparison of foamed asphalt and emulsion as
recycling agents and performance
• Direct comparison of multi-unit and single-unit CIR
equipment and performance of end-product
• Direct comparison of different maximum gradation sizing
requirements on CIR performance
• Evaluation of pilot projects currently in progress

14. Caltrans Cold Central Plant Recycling
◼ nSSP development
complete early 2022
• Currently identifying pilot
projects for CCPR to be
constructed in 2022 and
2023
• Ultimate goal will be to
combine FDR or Soil
Stabilization with CCPR and
overlay to create stronger
structural sections
◼ MPQP and Mix Design
procedures developed
concurrently to allow for
immediate
implementation

15. Caltrans PDR and CCPR
Specifications
Industry/Caltrans task group has completed developing specifications
for both CIR (PDR) and CCPR
PDR specifications allow for larger maximum aggregate size (1.25”) but
this is being evaluated. CCPR specifications require maximum 1”
aggregate size
This sizing is still being evaluated for possibility to revert
CIR (PDR) specification to 1” maximum
Mix Design procedures still in review – goal is to standardize both to
follow same outline
TSR and Marshall Testing
Standardized gradations for testing
Results with and without cement additive
Effectiveness of re-compaction and temperature
variations

16. Other Agencies and CR Status
◼ Most City/County agencies maintain separate CIR
specifications based on preference
• CIR using Emulsion still more commonly used, particularly in
Southern California
◼ CCPR utilization increasing, both foamed asphalt and
emulsion
• Combination with FDR and Soil Stabilization proving to provide
greatest cost/benefit
• Can be used with existing RAP stockpiles or with harvested RAP
from project sites
◼ SSPWC (Greenbook) currently in process of completing
CIR and CCPR specifications to be included in next update

17. Project Profiles
◼ City of Corona – Ontario Avenue
• Cold In-place Recycling using Emulsified Recycling Agent
◼ City of Industry – Arenth Avenue
• Cold Central Plant Recycling using Emulsified Recycling
Agent over Full-depth Reclamation
◼ City of Davis – Covell Boulevard
• Cold In-place Recycling using Foamed Asphalt
◼ County of Fresno – Lincoln Avenue
• Cold Central Plant Recycling using Foamed Asphalt

18. City of Corona
Cold-in-Place Recycling
Location: Ontario Avenue from California Avenue to Magnolia Avenue
Description: Consisted of Cold In-place Recycling to a depth of
3” with HMA overlay placed to a thickness of 2”
Schedule: Construction started in May 2018 and was completed in
November 2018.
Project Cost: $ 1,500,617.41
Funding: Measure A, Gas Tax, and Public Works Transportation
Grant

19. Ontario Avenue C.I.R. California Avenue to
Magnolia Avenue

20. Four long segments between intersections with 3
lanes in each direction

21. The long road segments and busy commercial
centers made CIR an ideal alternative to
conventional grinding and an AC overlay

22. Ontario Avenue C.I.R. California Avenue to
Magnolia Avenue
Intersections were closed only for short periods
of time
DURING CONSTRUCTION DURING CONSTRUCTION

23. Ontario Avenue C.I.R. California Avenue to
Magnolia Avenue
BEFORE CONSTRUCTION AFTER CONSTRUCTION

24. Ontario Avenue C.I.R. California Avenue to Magnolia
Avenue
Impact to motorists and businesses was minimal
BEFORE CONSTRUCTION AFTER CONSTRUCTION

25. CIR provided 20% reduction of project schedule and
990 fewer trucks to remove and replace pavement
BEFORE CONSTRUCTION AFTER CONSTRUCTION

26. City of Industry
Cold Central Plant Recycling
Location: Arenth Avenue from Nogales Street to Phillips Drive
Description: Rehabilitation of existing roadway by cold
planing, Full-depth Reclamation to a depth of
20”, CCPR to a depth of 6.5” and HMA overlay of
3.5”
Schedule: Two phases – First phase constructed in late 2020 and
second phase constructed in mid-2021
Project Cost: Phase 1 (1 mile) $2.96M
Phase 2 (1.5 miles) $4.78M

27. Arenth Avenue

28. Arenth
Avenue
◼ Existing
Conditions
◼ 4.75-inches to
8-inches of
asphalt
◼ 5-inches to 10-
inches of
aggregate base
◼ Paving fabric at
a depth of 1.5-
inches to 2.5-
inches
◼ R-value of
Subgrade
ranged from 7
to 40.
• 7 used for all
designs
Original
Design

29. Arenth Avenue
◼ Sustainable Design
◼ Utilization of most
or all RAP
generated from
milling
◼ Account for
approximate 5%
loss of RAP during
fabric
removal/disposal
• Original
• 6-inches HMA
• 30.5-inches
Aggregate Base
• 18-inches
engineered fill
• Sustainable
• 3.5-inches HMA
• 6.5-inches CCPR
• 20-inches
Cement Treated
Subgrade (5%)

30. Arenth Avenue
◼ Volume and Stockpile
Management
◼ RAP management –
design to avoid RAP
import
◼ Paving fabric –
Manage cold planing
to ensure efficient
removal and
minimal waste
◼ Minimize export at
end of each section

31. Arenth Avenue
◼ Stabilization – 20-
inches using 5%
cement
◼ Microcracking between
48 and 72 hours after
mixing
◼ CCPR – Performed in
2 lifts
◼ Lift 1 – 3.5-inches
◼ Lift 2 – 3-inches
◼ Supplemental
compaction
• 4-6 hours after initial
compaction on lift 1
• After 48 hours cure
and moisture testing
on lift 2

32. City of Davis
Cold-in-Place Recycling
Location: Covell Avenue from SR 113 to F Street
Description: Consisted of Cold In-place Recycling using Foamed
Asphalt to a depth of 3” with HMA overlay placed to
a thickness of 2”
Schedule: Construction started in August 2021 and was completed in
November 2021.

33. City of Davis
Covell Avenue Cold In-place Recycling

34. • Combination of Commercial and Residential Areas, approx.
1.2 miles long
• Schedule required completion in segments to maintain
traffic access
City of Davis
Covell Avenue Cold In-place Recycling
• Inclement Weather
• Davis received
approximately 2”-3” rain
in the days following CIR
construction.
• CIR was maintained
properly with minimal
damage. HMA placed
after rain concluded.

35. County of Fresno
Cold Central Plant Recycling
Location: Lincoln Avenue from SR 145 to Fig Avenue
Description: Rehabilitation of existing roadway by cold
planing, placing CCPR to a depth of 3”-4” and
HMA overlay of 2.4”
Quantity: 43,707 tons of CCPR

36. Lincoln
Avenue
◼ Construction
ongoing
◼ CCPR
starting this
summer
• Expected Benefits:
• 54,000 Trucking
Miles saved from
surrounding roads
• 24,000 CY saved
from landfill
disposal