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Gene Skok (UofM) Shongtao Dai (MnDOT) 12 th Minnesota Pavement Conference February 14, 2008

Mn/DOT Office of Materials and Road Research. MnPavement Rehabilitation Best Practices LRRB Inv 808. Gene Skok (UofM) Shongtao Dai (MnDOT) 12 th Minnesota Pavement Conference February 14, 2008. Outline. Objectives Literature Review Types of Reclamation Definition of Factors

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Gene Skok (UofM) Shongtao Dai (MnDOT) 12 th Minnesota Pavement Conference February 14, 2008

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  1. Mn/DOT Office of Materials and Road Research MnPavement RehabilitationBest PracticesLRRB Inv 808 Gene Skok (UofM) Shongtao Dai (MnDOT) 12th Minnesota Pavement Conference February 14, 2008

  2. Outline Objectives Literature Review Types of Reclamation Definition of Factors Decision Checklists Criteria Recommendations

  3. Pavement Rehabilitation (LRRB INV 808)Objective • Laying out the Best Practices for the selection of asphalt concrete • recycling techniques: • Full-Depth Reclamation (FDR) • Cold In-place Recycling (CIR) • Mill/Overlay (M&O).

  4. Why Mill and Overlay ? • Low Initial Cost • Minimize clearance/grade issues • Construction time minimized • “Covers” up reflective cracks

  5. Rehabilitation Decision Factors Existing Conditions (PQI) Ride (RQI) Surface Rating (SR) Transverse Cracks (0.01, 0.10, 0.20) Long. Cracks & Deter. (0.02, 0.03, 0.04) ….

  6. Rehabilitation Decision Factors (cont.) Multiple Cracking (0.15) Alligator Cracking (0.35) Rutting (0.15) Raveling & Weathering (0.02) Patching (0.04) PQI = (RQI X SR)1/2

  7. STRUCTURAL ADEQUACY • TONNAGE • PAVEMENT THICKNESS DESIGN Soil Factor (GE vs HCADT) R-Value (GE vs ESAL’s) Mn/PAVE (Thickness vs Load Spectra)

  8. Pavement Rehabilitation Database • Location • Original Pavement Construction • Pre-Rehab • Rehab • Post-Rehab

  9. Pavement Rehabilitation Database

  10. MN Rehabilitation ProjectsSurveys CIR (37) FDR (41) M&O (25)

  11. Pre-Rehab. SR Values for C.I.R. Projects SR Values

  12. Pre Rehabilitation SR Value for FDR Projects SR Values

  13. Pre-Rehabilitation SR Value for Mill and Overlay Projects SR levels

  14. SR Values before and after Rehabilitation Degradation Curves

  15. Surface Rating (SR) Degradation Rates

  16. SR Values for Individual FDR Projects Degradation curves

  17. Transverse Cracking IWD for FDR Projects . Condition Histories

  18. Transverse Cracks I.W.D. for S.R. Level TC effect on SR

  19. Decision Check Lists • Geometrics • Pavement Condition (s) • Review Figure 3.7 (PQI < 2.5) • Structural Adequacy • Pavement Thickness • Tonnage • Falling Weight Deflectometer

  20. Geometrics Checklist • Clearances • Shoulder Width • Grading Width • Curb and Gutter • Constructability

  21. Geometrics • 3.6 GEOMETRIC CONSIDERATIONS • NOTE: Official State Aid rules can be found directly at http://www.revisor.leg.state.mn.us/bin/getpub.php?pubtype=RULE_CHAP&year=current&chapter=8820 • OR by browsing to www.leg.state.mn.us and then selecting: • Statues, Session Laws, and Rules • Under the “Minnesota Rules” section on the main page, “Retrieve an entire chapter” • Enter in the number “8820” and click “Get Chapter”

  22. Pavement ConditionsChecklist Table 3.6. Pavement Condition(s) Checklist Ride Quality Index (RQI) 1.Methoda. ___________________ Critical Value __________ 1. Using Mn/DOT Van 2. Rating Panel 2. Rated by a panel Surface Rating (SR) Condition Individual Weighted Distress (IWD) 1.Rut Depth ___________________ 2.Transverse Cracking a.Low Severity __________ b.Medium Severity __________ c. High Severity __________ Total T.C. IWD ___________________ 3. Long. Cracking/ Joint Det. ___________________ 4. Alligator Cracking ___________________ 5. Raveling, Weather, Patch ___________________ Total IWD ___________________ SR _________________ PQI _________________ Discussion __________________________________________________________ __________________________________________________________ __________________________________________________________

  23. Selection of Rehabilitation Procedure based on Surface Ratings Procedure Selection

  24. Structural Adequacy Table 3.7 Summary of Structure Adequacy. PAVEMENT THICKNESS 1. Design Procedure: a. Soil Factor ___, R-Value ____, Mechanistic ___ b. Soil Type (Classification) AASHTO Class ________ R- Value ________ Measured ___ Estimated ____ Resilient Modulus _____ Measured ___ Estimated ___ c. Traffic (20 –year Predicted): AADT ___________ HCAADT __________ ESAL’s __________________ d.Required Thickness (Granular Equivalent Thickness) Soil Factor Procedure _____________ R-Value Procedure _______________ Mn PAVE _______________________ NOTES ___________________________________________________ ____________________________________________________ ____________________________________________________

  25. SPECIFIC CRITERIA 1. Is existing HMA thickness adequate to support CIR equipment? (3.5 in.)? 2. Is existing subgrade stiffness adequate to support CIR equipment? (5000 psi)? 3. Consider SR degradation rate.

  26. Criteria Continued 4. If not structurally adequate then CIR should NOT be used without additional overlay 5.If SR < 2.5 and IWD for multiple cracking or T.C. > 5.0: - Mill and OL should not be used - if existing HMA > 3.5 in. use FDR or RIC - if existing HMA < 3.5 in. use FDR only

  27. Criteria Continued more 6. If the SR < 2.5 and Mult. or Transverse cracking IWD is < than 5.0, use mill & overlay 7. Finally, cost/benefits should be considered along with decay rates in the final decision. NOTE: T.C. IWD = 5.0 for a pavement with all medium severity T.C. represents a crack count of 50 cracks per 100 ft. An IWD = 5.0 for a pavement with all high severity T.C. represents a crack count of 25 cracks per 100 ft.

  28. RECOMMENDATIONS • Determine ride (RQI) periodically with Mn/DOT IRI correlation(s) or panel • Determine IWD and SR using Mn/DOT Distress Manual periodically • Run FWD periodically to determine: • Tonnage • Subgrade Stiffness • GE of pavement section

  29. RECOMMENDATIONS (cont.) 4. Continue documenting performance information from 1., 2., and 3. in the rehabilitation database (?) - include RQI, SR (IWD’s), GE, Soil Stiffness. This could be part of the PMS or Mn/ROAD database (s).

  30. Summary • Types of Reclamation • Decision Factors • Database Development • Decision Checklists • Criteria • Recommendations

  31. Acknowledgements • Minnesota Local Road Research Board • Technical Advisory Committee • Mn/DOT, Dave Janisch, Erland Lukanen, Graig Gilbertson,Perry Collins • Counties, Brian Noeltzman,Wayne Olson,Milt Hagen,Brad Wentz,Brian Shepard,Kathy Jaschke,Darrell Pettis, Curt Bolles, Guy Kohnlhofer, • Midwest Construction, Tom Olson,American Engineering, Dave Rettner, SEM Materials,Dan Wegman,

  32. THANK YOU!, Any Questions?

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