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

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”

Background Highlights (Mn) 1980’s CIR Projects and Issues 1998 Joint Agency/Ind Mtg on CIR 2000 1st 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.

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

Mn/Road – I 94

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

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” 64-34 : Hot Mix Asphalt-SemMaterials study)

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%

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

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

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

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

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.

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

1.5 - 3” SMA, OGFC or Superpave } 1.5 - 3” 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

MnRoad Cells 2,3,4

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

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

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.

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

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.

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

Background Highlights (Mn) 1980’s CIR Projects and Issues 1998 Joint Agency/Ind Mtg on CIR 2000 1st 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 Barriers that recycle coalition and Agencies can address together.

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?