Mn/DOT Office of Materials and Road Research Gene Skok (UofM) Shongtao Dai (MnDOT) 12 th Minnesota Pavement Conference February 14, 2008 MnPavement Rehabilitation Best Practices LRRB Inv 808

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

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).

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

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) ….

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

STRUCTURAL ADEQUACY TONNAGE PAVEMENT THICKNESS DESIGN Soil Factor (GE vs HCADT) R-Value (GE vs ESALs) Mn/PAVE (Thickness vs Load Spectra)

Pavement Rehabilitation Database Location Original Pavement Construction Pre-Rehab Rehab Post-Rehab

Pavement Rehabilitation Database

MN Rehabilitation Projects Surveys CIR (37) FDR (41) M&O (25)

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

Pre Rehabilitation SR Value for FDR Projects SR Values

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

SR Values before and after Rehabilitation Degradation Curves

Surface Rating (SR) Degradation Rates Rehabilitation Procedure Deterioration Rate Cold In-Place Recycling Full Depth Reclamation Thin Mill & O.L Medium Mill & O.L Thick Mill & O.L

SR Values for Individual FDR Projects Degradation curves

Transverse Cracking IWD for FDR Projects Condition Histories.

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

Decision Check Lists 1. Geometrics 2. Pavement Condition (s) 3. Review Figure 3.7 (PQI < 2.5) 4. Structural Adequacy a. Pavement Thickness b. Tonnage c. Falling Weight Deflectometer

Geometrics Checklist Clearances Clearances Shoulder Width Shoulder Width Grading Width Grading Width Curb and Gutter Curb and Gutter Constructability Constructability

Geometrics 3.6 GEOMETRIC CONSIDERATIONS 3.6 GEOMETRIC CONSIDERATIONS NOTE: Official State Aid rules can be found directly at ype=RULE_CHAP&year=current&chapter=8820 NOTE: Official State Aid rules can be found directly at ype=RULE_CHAP&year=current&chapter= ype=RULE_CHAP&year=current&chapter= ype=RULE_CHAP&year=current&chapter=8820 OR by browsing to and then selecting: OR by browsing to and then selecting: Statues, Session Laws, and Rules Statues, Session Laws, and Rules Under the Minnesota Rules section on the main page, Retrieve an entire chapter Under the Minnesota Rules section on the main page, Retrieve an entire chapter Enter in the number 8820 and click Get Chapter Enter in the number 8820 and click Get Chapter

Pavement Conditions Checklist 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) ConditionIndividual Weighted Distress (IWD) 1.Rut Depth___________________ 2.Transverse Cracking a.Low Severity__________ b.Medium Severity__________ c. High Severity__________ Total T.C. IWD ___________________ Total T.C. IWD ___________________ 3.Long. Cracking/ Joint Det. ___________________ 4. Alligator Cracking ___________________ 5. Raveling, Weather, Patch ___________________ Total IWD ___________________ SR _________________ PQI _________________ PQI _________________ Discussion __________________________________________________________ __________________________________________________________ ____________________________________________________________________________________________________________________

Selection of Rehabilitation Procedure based on Surface Ratings Procedure Selection

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

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.

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: 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

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.

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

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

Summary Types of Reclamation Types of Reclamation Decision Factors Decision Factors Database Development Database Development Decision Checklists Decision Checklists Criteria Criteria Recommendations Recommendations

Acknowledgements Minnesota Local Road Research Board Minnesota Local Road Research Board Technical Advisory Committee Technical Advisory Committee Mn/DOT, Dave Janisch, Erland Lukanen, Graig Gilbertson,Perry Collins 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, 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, Midwest Construction, Tom Olson,American Engineering, Dave Rettner, SEM Materials,Dan Wegman,

THANK YOU!, Any Questions?