Mn/DOTOffice of Materials and Road Research

Gene Skok (UofM)Gene Skok (UofM)

Shongtao Dai (MnDOT)Shongtao Dai (MnDOT)

1212thth Minnesota Minnesota

Pavement ConferencePavement Conference

February 14, 2008February 14, 2008

MnPavement RehabilitationBest PracticesLRRB Inv 808

OutlineOutline

ObjectivesObjectives Literature ReviewLiterature Review Types of ReclamationTypes of Reclamation Definition of FactorsDefinition of Factors Decision ChecklistsDecision Checklists CriteriaCriteria RecommendationsRecommendations

Pavement Pavement RehabilitationRehabilitation

(LRRB INV 808) (LRRB INV 808)

ObjectiveObjective

Laying out the Best Practices for the selection of asphalt concreterecycling techniques:• Full-Depth Reclamation (FDR) • Cold In-place Recycling (CIR) • Mill/Overlay (M&O).

Why Mill and Overlay ?Why Mill and Overlay ?

Low Initial CostLow Initial Cost Minimize clearance/grade issuesMinimize clearance/grade issues Construction time minimizedConstruction time minimized ““Covers”Covers” up reflective cracks up reflective cracks

Rehabilitation Decision Rehabilitation Decision FactorsFactors

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 Rehabilitation Decision Factors (cont.)(cont.)

Multiple Cracking (0.15)Multiple Cracking (0.15)Alligator Cracking (0.35)Alligator Cracking (0.35)Rutting (0.15)Rutting (0.15)Raveling & Weathering (0.02)Raveling & Weathering (0.02)Patching (0.04)Patching (0.04)

PQI = (RQI X SR)PQI = (RQI X SR)1/21/2

STRUCTURAL ADEQUACYSTRUCTURAL ADEQUACY

• TONNAGE• PAVEMENT THICKNESS DESIGN

Soil Factor (GE vs HCADT)

R-Value (GE vs ESAL’s)

Mn/PAVE (Thickness vs Load

Spectra)

Pavement Rehabilitation Pavement Rehabilitation DatabaseDatabase

• Location• Original Pavement Construction• Pre-Rehab• Rehab• Post-Rehab

Pavement Rehabilitation Pavement Rehabilitation DatabaseDatabase

MN Rehabilitation MN Rehabilitation ProjectsProjectsSurveysSurveys

CIR (37)

FDR (41)

M&O (25)

District 1

District 3

District 8

District 7 District 6

Metro

District 2

District 4

District 1

District 3

District 8

District 7 District 6

Metro

District 2

District 4

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

SR ValuesSR Values

0

0.5

1

1.5

2

2.5

3

3.5

4

Project

SR FDR

Average

Pre Rehabilitation SR Value for Pre Rehabilitation SR Value for FDR ProjectsFDR Projects

SR ValuesSR Values

0

0.5

1

1.5

2

2.5

3

3.5

4

Project

SR FDR

Average

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

SR levelsSR levels

0

0.5

1

1.5

2

2.5

3

3.5

4

Project

SR M&O

Average

SR Values before and SR Values before and after Rehabilitationafter Rehabilitation

Degradation CurvesDegradation Curves

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

-20 -15 -10 -5 0 5 10 15 20

Year from rehab

SR

CIR

FDR

Med. M&O

Thick M&O

Surface Rating (SR) Surface Rating (SR) Degradation RatesDegradation Rates

Rehabilitation Rehabilitation ProcedureProcedure

Deterioration RateDeterioration Rate

Cold In-Place Cold In-Place RecyclingRecycling

0.0400.040

Full Depth Full Depth ReclamationReclamation

0.0210.021

Thin Mill & O.L.Thin Mill & O.L. 0.0400.040

Medium Mill & O.L.Medium Mill & O.L. 0.0650.065

Thick Mill & O.L.Thick Mill & O.L. 0.0210.021

SR Values for Individual SR Values for Individual FDR ProjectsFDR Projects

Degradation curvesDegradation curvesSR Before/After (FDR)

0

0.5

1

1.5

2

2.5

3

3.5

4

-15 -10 -5 0 5 10 15

Year Relative to Rehab

SR

4

5

8

9

10

12

13

15

27

28

31

32

33

48

30

Transverse Cracking IWD Transverse Cracking IWD for FDR Projectsfor FDR Projects

Condition HistoriesCondition Histories

.

Transverse Distress (CIR)

0

1

2

3

4

5

6

7

8

9

-20 -15 -10 -5 0 5 10 15 20

Year Relative to Rehab

Tra

nsv

erse

IWD

1

2

16

17

18

19

20

21

22

25

40

41

42

43

45

46

47

49

Transverse Cracks I.W.D. Transverse Cracks I.W.D. for S.R. Levelfor S.R. Level

TC effect on SRTC effect on SR

0

1

2

3

4

5

6

7

8

9

0 0.5 1 1.5 2 2.5 3 3.5 4

Overall SR

Tra

nsv

erse

Cra

ck IW

D

0

1

2

3

4

5

6

7

8

9

CIR

FDR

M&O

Typical

Decision Check ListsDecision Check Lists

1.1. GeometricsGeometrics

2.2. Pavement Condition (s)Pavement Condition (s)

3.3. Review Figure 3.7 (PQI < 2.5)Review Figure 3.7 (PQI < 2.5)

4.4. Structural AdequacyStructural Adequacya.a. Pavement ThicknessPavement Thickness

b.b. TonnageTonnage

c.c. Falling Weight DeflectometerFalling Weight Deflectometer

Geometrics ChecklistGeometrics Checklist

ClearancesClearances Shoulder WidthShoulder Width Grading WidthGrading Width Curb and GutterCurb and Gutter ConstructabilityConstructability

GeometricsGeometrics

3.6 GEOMETRIC CONSIDERATIONS3.6 GEOMETRIC CONSIDERATIONS NOTE: Official State Aid rules can be found NOTE: Official State Aid rules can be found

directly at directly at http://http://www.revisor.leg.state.mn.us/bin/getpub.php?pubtwww.revisor.leg.state.mn.us/bin/getpub.php?pubtypeype==RULE_CHAP&yearRULE_CHAP&year==current&chaptercurrent&chapter=8820=8820

OR by browsing to OR by browsing to www.leg.state.mn.uswww.leg.state.mn.us and then and then selecting:selecting:

Statues, Session Laws, and RulesStatues, Session Laws, and Rules Under the “Minnesota Rules” section on the main Under the “Minnesota Rules” section on the main

page, “Retrieve an entire chapter”page, “Retrieve an entire chapter” Enter in the number “8820” and click “Get Enter in the number “8820” and click “Get

Chapter”Chapter”

Pavement ConditionsPavement ConditionsChecklistChecklist

Table 3.6. Pavement Condition(s) ChecklistTable 3.6. Pavement Condition(s) ChecklistRide Quality Index (RQI)Ride Quality Index (RQI)

1.Methoda. ___________________1.Methoda. ___________________ Critical Value __________Critical Value __________1. Using Mn/DOT Van 2. Rating Panel1. Using Mn/DOT Van 2. Rating Panel

2. Rated by a panel2. Rated by a panelSurface Rating (SR)Surface Rating (SR)

ConditionCondition Individual Weighted Distress (IWD)Individual Weighted Distress (IWD)1.Rut Depth1.Rut Depth ______________________________________2.Transverse Cracking2.Transverse Cracking

a.Low Severitya.Low Severity ____________________b.Medium Severityb.Medium Severity ____________________c. High Severityc. High Severity ____________________

Total T.C. IWD ___________________Total T.C. IWD ___________________3.3. Long. Cracking/ Joint Det.Long. Cracking/ Joint Det. ___________________ ___________________4. Alligator Cracking4. Alligator Cracking ___________________ ___________________5. Raveling, Weather, Patch5. Raveling, Weather, Patch ___________________ ___________________

Total IWDTotal IWD ______________________________________

SRSR _________________ _________________ PQIPQI _________________ _________________

Discussion __________________________________________________________Discussion __________________________________________________________ ____________________________________________________________________________________________________________________

____________________________________________________________________________________________________________________

Selection of Rehabilitation Selection of Rehabilitation Procedure based on Surface Procedure based on Surface

RatingsRatingsProcedure SelectionProcedure Selection

Selection of Rehabilitation Procedures based on Surface Conditions

IWD(Mult) > 5and/or

IWD(Trans) > 5

HMA > 4”FDR

CIR

HMA < 4” FDR

IWD(Mult) < 5and

IWD(Trans) < 5

RQI > 3.0 Thin M&O

RQI < 3.0 Med. or Thick M&O

For SR =< 2.5

Expected Life

(see Table 3.3 and 3.6)

Structural AdequacyStructural Adequacy

Table 3.7 Summary of Structure Adequacy.Table 3.7 Summary of Structure Adequacy.PAVEMENT THICKNESSPAVEMENT THICKNESS

1. Design Procedure: 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 ________ AASHTO Class ________ R- Value ________R- Value ________

Measured ___Measured ___Estimated ____Estimated ____

Resilient Modulus _____Resilient Modulus _____Measured ___Measured ___Estimated ___Estimated ___

c. Traffic (20 –year Predicted):c. Traffic (20 –year Predicted):AADT ___________AADT ___________ HCAADT __________HCAADT __________ESAL’s __________________ESAL’s __________________

d.Required Thickness (Granular Equivalent Thickness)d.Required Thickness (Granular Equivalent Thickness)Soil Factor Procedure _____________Soil Factor Procedure _____________R-Value Procedure _______________R-Value Procedure _______________ Mn PAVE _______________________Mn PAVE _______________________

NOTES ___________________________________________________NOTES ___________________________________________________ ________________________________________________________________________________________________________ ________________________________________________________________________________________________________

SPECIFIC CRITERIASPECIFIC CRITERIA

1. Is existing HMA thickness adequate 1. Is existing HMA thickness adequate to support CIR equipment?to support CIR equipment?

(3.5 in.)?(3.5 in.)?

2. Is existing subgrade stiffness 2. Is existing subgrade stiffness adequate to support CIR equipment?adequate to support CIR equipment?

(5000 psi)?(5000 psi)?

3. Consider SR degradation rate.3. Consider SR degradation rate.

Criteria ContinuedCriteria Continued

4. If not structurally adequate then CIR should 4. If not structurally adequate then CIR should NOTNOT be used without additional overlay be used without additional overlay

5.If SR < 2.5 and IWD for multiple cracking or5.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- 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 or RIC

- if existing HMA < 3.5 in. use FDR only - if existing HMA < 3.5 in. use FDR only

Criteria Continued moreCriteria Continued more

6. If the SR < 2.5 and Mult. or Transverse cracking 6. If the SR < 2.5 and Mult. or Transverse cracking IWD is < than 5.0, use mill & overlayIWD is < than 5.0, use mill & overlay

7. Finally, cost/benefits should be considered along 7. Finally, cost/benefits should be considered along with decay rates in the final decision.with decay rates in the final decision.

NOTE: T.C. IWD = 5.0 for a pavement with all NOTE: T.C. IWD = 5.0 for a pavement with all mediummedium severity T.C. represents a crack count of severity T.C. represents a crack count of 50 cracks per 100 ft.50 cracks per 100 ft.

An IWD = 5.0 for a pavement with all An IWD = 5.0 for a pavement with all high high severity T.C. represents a crack count of 25 severity T.C. represents a crack count of 25 cracks per 100 ft. cracks per 100 ft.

RECOMMENDATIONSRECOMMENDATIONS

Determine ride (RQI) periodically with Determine ride (RQI) periodically with Mn/DOT IRI correlation(s) or panelMn/DOT IRI correlation(s) or panel

Determine IWD and SR using Mn/DOT Determine IWD and SR using Mn/DOT Distress Manual periodicallyDistress Manual periodically

Run FWD periodically to determine:Run FWD periodically to determine:- TonnageTonnage- Subgrade StiffnessSubgrade Stiffness- GE of pavement sectionGE of pavement section

RECOMMENDATIONS (cont.)RECOMMENDATIONS (cont.)

4. Continue documenting performance 4. Continue documenting performance information from 1., 2., and 3. in the information from 1., 2., and 3. in the rehabilitation database (?)rehabilitation database (?)

- include RQI, SR (IWD’s), GE, Soil - include RQI, SR (IWD’s), GE, Soil Stiffness. This could be part of the Stiffness. This could be part of the PMS or Mn/ROAD database (s).PMS or Mn/ROAD database (s).

SummarySummary

Types of ReclamationTypes of Reclamation Decision FactorsDecision Factors Database DevelopmentDatabase Development Decision ChecklistsDecision Checklists CriteriaCriteria RecommendationsRecommendations

AcknowledgementsAcknowledgements

Minnesota Local Road Research BoardMinnesota Local Road Research Board Technical Advisory CommitteeTechnical Advisory Committee Mn/DOT, Dave Janisch, Erland Lukanen, Graig Mn/DOT, Dave Janisch, Erland Lukanen, Graig

Gilbertson,Perry CollinsGilbertson,Perry Collins Counties, Brian Noeltzman,Wayne Olson,Milt Counties, Brian Noeltzman,Wayne Olson,Milt

Hagen,Brad Wentz,Brian Shepard,Kathy Hagen,Brad Wentz,Brian Shepard,Kathy Jaschke,Darrell Pettis, Curt Bolles, Guy Jaschke,Darrell Pettis, Curt Bolles, Guy Kohnlhofer,Kohnlhofer,

Midwest Construction, Tom Olson,American Midwest Construction, Tom Olson,American Engineering, Dave Rettner, SEM Materials,Dan Engineering, Dave Rettner, SEM Materials,Dan Wegman, Wegman,

THANK YOU!, Any THANK YOU!, Any Questions?Questions?