1. 2017 Pavement Conference May 24, 2017 Dan Wegman
“Asphalt Recycling: Key Research, Best Practices and Successful Implementation”
2017 Pavement Conference
May 24, 2017
Dan Wegman

2. In-place Recycling: Most Common Bituminous Recycling Options
Cold In-Place Recycling
Full Depth Reclaimation
Most common, most performance data, Proven technology – Should no longer be considered “new”

3. Background Highlights (Mn)
1980’s CIR Projects and Issues
1998 Joint Agency/Ind Mtg on CIR
st SFDR Project Chisago Cty
2002 FHWA Mandate on Recycling
2008 Cells 2,3 and 4 Constructed
2013 Considerable Perf Data
2017 Still limited use by Agencies
WHY ?
Emphasize improvements in equipment, materials and process application. Agencies have not provided any compelling reasons for not making a standard practice with several projects in each District every year.

4. Office of Materials and Road Research
MnRoad Cells 2,3,4
Cooperative project: MnDOT and Road Science LLC
Objective:
Study how the emulsion-stabilized FDR affects pavement responses (stress, strain) and performance.
Test Cells have exposed performance attributes providing superior life cycle cost and performance
Mn/DOT
Office of Materials and Road Research

5. Mn/Road – I 94

6. I - 94 Albertville Mn/Road – I 94
Cell 2
50% RAP
Cell 3
75% RAP
Cell 4
100% RAP
Brief intro on test cell design

7. Three test sections constructed at MnROAD in 2008
Cell 2, 3 and 4
Interstate live traffic (I-94)
Very thin HMA layer
The Project included reclaiming
12” on Cell 2 (6” HMA + 6” aggregate base)
8” on Cell 3 (6” HMA+ 2” aggregate base)
And treating the top 6” of reclaimed asphalt with an engineered emulsion (EE).
On Cell 4 the top 8” of HMA was milled and set aside for later use
New construction
1” TBWC: Ultra Thin Bonded (Novachip)
1” : Hot Mix Asphalt-SemMaterials study)

8. Base Stabilization Cells 2,3,4
50%
RAP
6 inch
Stab. 4% EE 3
75% 3% 4
100%
8 inch
.075%
SHLD
4 inch
4.5%

9. Design Life: 3.5 M ESAL (Road Science LLC)
The ESAL level is expected to occur in a time period of approximately five years.
Estimated traffic (I-94): Feb.09 – fall 16: ~ 6.0 M ESAL
Performing better than expectation

10. Distress as of 2016 Minimal transverse cracking
Low severity raveling on Cell2 and Cell4
Low severity bleeding Cell 3
Longitudinal joint deterioration on Cell 3
Minimal fatigue cracks!!
Performance summary of test cells. Still performing extremely well with almost 2 times the original design esals

11. Perpetual Pavement Three Layer System
Perpetual Pavement Concept helps explain why recycling in place extends pavement performance and life
Newcomb et al, 2000

12. High Strain = Short Life
Fatigue Theory
High Strain = Short Life
Low Strain = Long Life
Strain
Fatigue Life
Strain
Maximum tensile strains are at the bottom of the bound layer. It is important that recycled in place material is bound for perpetual pavement like performance. Bound requirement includes foamed asphalt, cement and engineered emulsion but excludes most proprietary products
Strain
Fatigue Life

13. Fatigue Endurance Limit
The fatigue endurance limit (EL) concept assumes a specific strain level, below which the damage in hot mix asphalt (HMA) is not cumulative  Unlimited Fatigue Life!
Unlimited
Fatigue
Life
Fatigue Life
Strain
Most research shows that around 70 to 200 microstrain meets EL. HMA overlay in cells 2,3,4 also meet the criteria.

14. Key to improved performance
Max Tensile Strain
50% less on HMA

15. 1.5 - 3” SMA, OGFC or Superpave}
” SMA, OGFC or Superpave
2-3”
Zone
Of High Compression
High Modulus
Rut Resistant Material
Flexible Fatigue Resistant
Material 6 - 8”
Max Tensile Strain
This is the concept underlying the perpetual pavement. Fatigue cracks also have difficulty finding a path to the pavement surface.
Traffic stresses are highest near the surface of the pavement, so materials in the upper pavement layers must be resistant to rutting.
The intermediate or binder courses should be comprised of rut-resistant material. Materials which have worked well include large-stone mixtures or others which provide a strong stone skeleton.
Fatigue resistance is important in the lowest HMA layer or base layer. It is well documented that the most costly form of distress to fix in a pavement is bottom-up fatigue cracking.
The pavement foundation serves as the ultimate support for the structure during construction and service, so it must be considered an integral part of the pavement.
Pavement Foundation

16. MnRoad Cells 2,3,4

17. Cost per Remaining Service Life Year Added Bituminous Treatments Terry Beaudry MEO Mtg 2017
HPMA Cost/Lane Mile
RSL Years
$/RSL/Year Added
CIR
$154,251 17
$9,074
Reclaim
$237,212 24
$9,884
Medium Mill/OL
$160,660 15
$10,711
Thick Mill/OL
$211,550
$12,444
Terry Beaudry presentation to MEO shows CIR to be the least expensive treatment when considering service life

18. Benefits: Why do CIR or SFDR
Cost effective - Nevada DOT reports a saving of $20 million year for the last 20 using blend of CIR and FDR – Often is Lowest Life Cycle Cost
Thicker Stabilized Section versus Mill and Fill or FDR
Can be used with HMA
or BOC
Cost effective versus un-bonded overlay
Green
Less green house gases given off
Less energy used
Less aggregate used
My Quick Calculation:
a CIR strategy can use ½ the new aggregate and less asphalt
Terry Beaudry MEO presentation outlining many benefits

19. Recycling FHWA - 2002 Recycled Materials Policy
Recycled materials should get first consideration in materials selection
Document reasoning for not using recycling processes
Recycling  engineering, economic & environmental benefits
Review engineering & environmental suitability
Assess economic benefits
Remove restrictions prohibiting use of recycled materials without technical basis
Unfunded Mandate was not followed. Required documentation not enforced. MnDot mandate got Districts to try at least one project but no follow through by Management.

20. Recycling Pitfalls/ Need for Best Practices
Unrealistic expectations from poor research conclusions
Proprietary product performance claims
Lack of proper up front assessment work
Product/Process selection
Lay groundwork for recycling coalition benefits

21. Pavement Assessment Pavement Strength Evaluation
Pavement Structural Capacity
Non-destructive testing methods include Falling Weight Deflectometer (FWD), Ground Penetrating Radar (GPR) and Dynamic Cone Penetrometer (DCP)
Destructive testing methods include soil borings, probe holes, test pits and coring
Level of pavement assessment addresses risk. Many agencies do not have adequate level of understanding of their in place pavements. Assessment can be done by Agency or contracted to service firms.

22. Full Depth Reclamation (FDR) Keys to Success
Stabilization Considerations
Foam Asphalt or Lime
Cutbacks or Road Mix
Proprietary Products
Engineered Emulsion
Fly Ash or Cement
Prone to
Cracking
Prone to
Rutting
Many binders to choose from, assessment helps in selection. Emphasize again the importance of recycle material being bound.
Stiff
Flexible
Organic
Clay
Granular

23. Background Highlights (Mn)
1980’s CIR Projects and Issues
1998 Joint Agency/Ind Mtg on CIR
st SFDR Project Chisago Cty
2002 FHWA Mandate on Recycling
2008 Cells 2,3 and 4 Constructed
2013 Considerable Perf Data
2017 Still limited use by Agencies
WHY ?

24. Recycle in Place What are some of the other barriers?
Paradigm Shift
Moving from “standard protocol” decision making
Agency Issues
Must be understood and accepted by all
Must be committed to by top management
Must have buy-in from Industry
Remove stigma that recycle is lower quality or “less value” than new construction
Industry Pressures
Introducing new technologies
Competition from industry (“rehab” and material suppliers)
Public Perception
Very positive once fully understood
Barriers that recycle coalition and Agencies can address together.

25. Successful Implementation
Find Statewide Implementation Champion
Create Technical Teams with Rep’s from each District
Establish Performance Measures and Initiate Performance Tracking
Commitment from Management, Industry

26. Thank You! Questions?