“Asphalt Recycling: Key Research, Best Practices and Successful Implementation” 2017 Pavement Conference May 24, 2017 Dan Wegman
In-place Recycling: Most Common Bituminous Recycling Options Cold In-Place Recycling Full Depth Reclaimation
Background Highlights (Mn) 1980’s CIR Projects and Issues 1998 Joint Agency/Ind Mtg on CIR 2000 1 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 ?
Mn. Road Cells 2, 3, 4 Cooperative project: Mn. DOT and Road Science LLC Objective: Study how the emulsion-stabilized FDR affects pavement responses (stress, strain) and performance. Mn/DOT Office of Materials and Road Research
Mn/Road – I 94
I - 94 Albertville Mn/Road – I 94 Cell 2 Cell 3 50% RAP 75% RAP Cell 4 100% RAP
Three test sections constructed at Mn. ROAD in 2008 F Cell 2, 3 and 4 F Interstate live traffic (I-94) F 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 1” TBWC: Ultra Thin Bonded (Novachip) 1” 64 -34 : Hot Mix Asphalt-Sem. Materials study)
Base Stabilization Cells 2, 3, 4 CELL 50% 2 RAP 6 inch 4% Stab. EE CELL 75% 3 RAP 6 inch 3% Stab. EE CELL 4 8 inch Stab. 100% RAP SHLD 50% RAP . 075% EE 4 inch 4. 5% Stab. EE
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
Distress as of 2016 F F F Minimal transverse cracking Low severity raveling on Cell 2 and Cell 4 Low severity bleeding Cell 3 Longitudinal joint deterioration on Cell 3 Minimal fatigue cracks!!
Perpetual Pavement Three Layer System Newcomb et al, 2000 11
Fatigue Theory High Strain = Short Life Strain Low Strain = Long Life Strain Fatigue Life 12
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 Strain Fatigue Life 13
Key to improved performance Max Tensile Strain 50% less on HMA
} 1. 5 - 3” SMA, OGFC or Superpave Zone Of High 2 -3” Compression Max Tensile Strain High Modulus Rut Resistant Material Flexible Fatigue Resistant Material 6 - 8” Pavement Foundation
Mn. Road Cells 2, 3, 4 16
Cost per Remaining Service Life Year Added Bituminous Treatments Terry Beaudry MEO Mtg 2017 Treatment 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 17 $12, 444 1 7
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
Recycling FHWA - 2002 Recycled Materials Policy Recycled materials should get first consideration in materials selection Document reasoning for not using recycling processes engineering, economic & environmental benefits Recycling Review Assess engineering & environmental suitability economic benefits Remove restrictions prohibiting use of recycled materials without technical basis
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
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 21
Pr C on ra e ck to in g R on ut e tin to g Pr As Fo ph am L i al m to e r Fl C y. A em sh en or t Pr Pr opr od ie uc tar ts y En Em gin ul ee si re on d C u R tba oa c d ks M o ix r Full Depth Reclamation (FDR) Keys to Success Stabilization Considerations Flexible Stiff Granular Organic Clay
Background Highlights (Mn) 1980’s CIR Projects and Issues 1998 Joint Agency/Ind Mtg on CIR 2000 1 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 ?
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
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
Thank You! Questions?
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