Unbonded CRCP Overlays

Jeffery Roesler, Ph.D., P.E.Professor

Department of Civil and Environmental EngineeringUniversity of Illinois Urbana-Champaign

FHWA-CRSI Creating Long Life Pavement Solutions -Continuously Reinforced Concrete Pavements Workshop

Fresno, CaliforniaFebruary 22, 2012

Acknowledgements

• Illinois Department of Transportation– Dave Lippert, Amy Schutzbach, Chuck

Wienrank

• Mike Plei

CRCP CRACKING PATTERN

Presentation Overview

• CRCP in heavy traffic areas in Illinois

• CRCP Unbonded Overlay Basics• Review of CRCP Overlay Projects• Key design issues for CRCP overlays• Illinois Experience with Unbonded CRCP• Summary

Example Urban CRCP

• Illinois experience: – I-90/94 Dan Ryan Expressway – Chicago– Other projects

• I-95 Georgia experience

Illinois Conditions

• Wet and Freeze-Thaw Climate• Limestone-Dolomite aggregates

– CTE=5.5x10-6/F• Design Flexural strength = 750 psi• Temperature Ranges:

– 0F to 100F• Long. Bars = 26 - #7 @5.5inch• Tranverse bars = #4 bars at 48 inches

ATLAS CRCP Testing

Summary of CRCP Section Failure

Section one

Section two

Section three

Section four

Section five

Duration of testing(1)12 months(6/16/02-6/23/03)

11 weeks (6/30/03-9/13/03)

10 weeks (5/26/04-8/4/04)

9 weeks (1/3/04-3/6/04)

2 weeks (4/6/04-4/15/04)

Total load repetitions 246,800 118,600 163,400 64,300 1,800

Total ESALs 911 M 778 M 627 M 764 M 12.5 M

Approx ESALs at first failure 511 M 230 M 548 M >764 M N/A

Maximum load applied 222 kN 222 kN 245 kN 245 kN 156 kN(3)

Pavement temperature range 1-27°C

(2) 24-35°C 18-27°C -4-10°C 4-18°C

Failure description Extended punchoutsExtended punchouts

Extended punchouts

Section did not fail

Response loading only

34k

1i

ii 40

Pn18ESALs

÷

Bituminous BaseAggregate Working Platform

Extended-Life CRCP DesignIllinois DOT (2005)

4 & 6 in.

40 Year

CRCP

Bituminous BaseAggregate Working Platform

12 to 24 inches

0.8% Steel Epoxy Coated

14 in.

Dan Ryan Expressway, I-90/94 (2007)

• Original CRCP design (1961)• 2006-2008 reconstruction for 500 million

ESALs and 40-year life.– Slab thickness = 14-in– Steel content = 0.80%– Steel depth = 4.5-in– Tied JPCP shoulder– 4-in dense graded HMA – Min. 12-in granular subbase– Fine grained subgrade (A-6 soil)

I-90/94 Dan Ryan Expressway Chicago

CRCP – Dan Ryan Expressway 40 Year

CRCP – Dan Ryan Expressway

• 5 mile project (I-80 to Indiana)• CRCP design ESALs= 175 million (40 yrs)

– 12-in CRCP– 0.75% steel– Depth of steel = 3.5-in– Tied JPCP shoulder– 4-in dense HMA base– 12-in granular subbase (PGE)– Fine grained subgrade (A-6 soil)

Illinois State Toll Highway Authority I-294 Chicago (2005)

15

• 12.5 mile project (I-80 to 95th)• CRCP design ESALs= >60 million (40 yrs)

– 13-in CRCP– 0.75% steel– Depth of steel = 3.5-in– Tied JPCP shoulder– 3-in dense HMA base– 24-in recycled concrete aggregate subbase– Fine grained subgrade (A-6 soil)

Illinois State Toll Highway Authority I-294 (2008-2009)

16

Other Illinois DOT CRCP Projects“Extended Life”

I-80* Morris2003

14in CRCP6in HMA

12in CRCP

I-70* Marshall2002

12in CRCP5in HMA8in CRCP

I-290 Schaumburg

200314in CRCP

6in HMA

24in Aggregate

I-74 Peoria2006

11.5in CRCP

6in HMA

12in Aggregate

12 14

14

11.5

*overlays

Continuously Reinforced Pavements• No man-made “joints”• Steel reinforcement bars• Numerous transverse cracks

Concrete Overlays CategoriesConcrete Overlays

Bonded Concrete Resurfacing of Concrete Pavements

Bonded Concrete Resurfacing of Asphalt Pavements

Bonded Concrete Resurfacing of Composite Pavements

Bonded Resurfacing Group

Unbonded Concrete

Resurfacing of Concrete Pavements

Unbonded Concrete

Resurfacing of Asphalt Pavements

Unbonded Concrete

Resurfacing of Composite Pavements

Unbonded Resurfacing Group

Thin Thick

Bond is integral to design Old pavement is Support

Pavement Overlay Comparisons Bonded

Concrete Overlays (BCOs)

Unbonded Concrete Overlays (UBOLs)

HMA Overlay on Intact CRCP

HMA Overlay on Rubblized CRCP

Con

stru

ctab

ility

Vertical Clearance

Not a problem (typically 50 to 100 mm (2-4 inches) thick)

May be a problem (typically 180 to 250 mm (7 to 10 inches) thick)

May or may not be a problem, depends on the overlay thickness

May be a problem, overlay may be relatively thick

Traffic Control May be difficult to construct under traffic

May be difficult to construct under traffic

Not difficult to construct under traffic

Not difficult to construct under traffic but rubblization adds time

Construction Special equipment and experienced operators needed

No special equipment required

No special equipment required

Special equipment required for rubblization

Perf

orm

ance

Existing CRCP Condition

Good condition with no MRD

All conditions (good to bad)

Good condition, may accelerate MRDs

Poor condition

Extent of Repair

Repair all deteriorated joints and cracks

Repair limited to severe damage

Repair all deteriorated joints and cracks

Limited repair required

Future Traffic Any traffic level Any traffic level Any traffic level Any traffic level Historical Reliability

Fair to Poor* Good Good Good to poor, depending on the support

Cos

t E

ffec

tiven

ess

Initial Cost Depends on pre-overlay repair, but usually high

Higher than conventional HMA overlay

Depends on the pre-overlay repairs

Requires a thick HMA overlay

Life Cycle Cost Analysis (LCCA)

Competitive if future life is substantial

Competitive Cost-effective unless the pavement is in poor condition

Competitive if pre-overlay repairs are required

(Smith et al. 2002)

Unbonded Concrete Overlay

Concrete Overlay hol

Existing Concrete Pavement

heSeparator layer

- Asphalt Concrete Interlayer

Unbonded CRCP OverlayObjective

• Isolate excessive movement of existing pavement from concrete overlay

• Limit concrete distress reflection into concrete overlay

• Provide uniform & non-erodible support to overlay

Concrete Overlay Stress Distribution

-100

0

100

200

300

400

500

600

700

800

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Distance from crack, in

Bot

tom

stre

sses

, psiO

OO

O

Noncrackked underlying slab Cracked underlying slab

Khazanovich et al. 2002

CRCP Unbonded Overlays General Overview

• Existing pavement condition is fair to poor• Asphalt separator layer or “bond-breaker”

– Friction layer that provides uniformity– Durable, moisture insensitive layer– Allows deflection profiles of two concrete

layers to be independent• Roadway & roadside geometrics

– shoulders, ramps, guardrail modifications

(Smith et al. 2002)

Unbonded CRCP Overlays Abridged History

• 600 miles of CRC Overlays (6 to 9-inches) since 1959 (CRSI 1988) – Waco, TX first CRCP overlay (CRSI 1973)– IN, MD, MS, TX, OR, IL, PA, ND, IA, CT

(PCA 1976)• Oregon DOT (e.g., 1970 to 1975)

– 4 projects (29.6 miles)• TxDOT (e.g., 1972- present) > 10 projects• Illinois DOT (1967- present) - 8 projects

Oregon I-5 CRCP Overlay(1970-1975)

CRSI 1988

7 to 9 inch CRCP over flexible pav’t

TxDOT Experience• I-35W Johnson County (1965)

– 6-inch CRCP over 9-inch JPCP– ADT=22,000 w/ 14% trucks– 8.78 mile section

• I-45W Galveston area (1972-1976)– 6-inch CRCP over JPCP– ADT=50,000 – 15.5 mile total section (4 projects) CRSI 1988

Recent TxDOT ProjectsCRCP Overlays

1. IH-30 in Paris District: existing pavement is JPCP2. IH-45 in Dallas District: existing pavement is JPCP.3. IH-35 in Wichita Falls District: existing pavement is CRCP.4. IH-45 in Houston District: existing pavement is JPCP.5. IH-20 in Fort Worth District: existing pavement is CRCP.6. IH-20 in Tyler District:7. IH-20 in Beaumont District: existing pavement is JRCP.8. IH-35W in Fort Worth District: existing pavement is JPCP.

from Moon Won

Arkansas DOT Experience• I-40/55 West Memphis (1972)

– 6-inch CRCP over 9-inch JPCP– ADT=27,000 w/ 25% trucks (1986)– 1.7 mile section

• I-55 West Memphis (1980)– 6-inch CRCP over 9-inch JPCP– ADT=26,600 w/ 28% trucks (1986)– 2.2 mile section

CRSI 1988

Unbonded CRCP Overlays Issues

1. Assessing existing pavement conditions2. Interlayer type and thickness3. Overlay structural design4. Pre-overlay repairs (?)5. Construction specifications and details

Condition Survey Information• Failures / mile• Materials-related distress (freeze-thaw,

ASR, etc.)• Deflection or PSIt• Drainage condition

– Interlayer or subbase erosion

CRCP Structural Evaluation Current Distress

Level Inadequate Marginal Adequate

Punchouts (M,H), # / lane km (#/ lane mi)

Interstate freeway > 6 (10) 3-6 (5-10) < 3 (5) Primary > 9 (15) 5-9 (8-15) < 5 (8) Secondary > 12 (20) 6-12 (10-20) < 6 (10)

Patch deterioration (M,H), % surface area

Interstate freeway > 5 2-5 < 2 Primary > 10 5-10 < 5 Secondary > 15 8-15 < 8

Longitudinal joint spalling (M,H), % length

Interstate freeway > 50 20-50 < 20 Primary > 60 25-60 < 25 Secondary > 75 30-75 < 30

Materials related distresses: D-cracking and ASR

All M to H severity with significant spalling & jt. disintegration

L to M severity with spalling & jt disintegration

None to L severity

Deterioration of past maintenance activities (patches and other repairs), % surface area

Interstate/Freeway > 8 3-8 12 5-12 15 10-15

Resurfacing Threshold Values TxDOT

• < 1.2 failures/km/yr (2 failures/mi/yr) allowed for thin HMA overlay used

• 1.2-1.9 failures/km/yr (2-3 failures/mi/yr) allowed for BCOs

• > 1.9 failures/km/yr (3 failures/mi/yr) allowed for UBCOLs

Failu

res /

km

Time

Thin HMA Overlay

UBOL

BCO

1.2 F/km/yr

1.9 F/km/yr

Failu

res /

km

Time

Thin HMA Overlay

UBOL

BCO

1.2 F/km/yr

1.9 F/km/yr

•CTR 920-F

CTR 1990

CRCP Pre-overlay repairs

Distress Types Repair Methods Wide transverse cracks with significant differential deflection

FDR

Punchouts FDR Unstable slabs with large deflections FDR

Slab stabilization Retrofit edge drains

Severely spalled joints or cracks FDR HMA filling

Pumping / Faulting (> 6 mm (0.25 in)) Retrofit edge drains Slab stabilization

Settlement Level-up with HMA Poor joint / crack load transfer Repair not necessary, but a thicker separation

layer should be considered Materials related durability problems: D-cracking or reactive aggregate

UBOLs can be constructed

after Smith et al. 2002, AASHTO 1993, ACPA 1990

Interlayer or Separation Layer Properties

• Dense-graded HMA– Provide interface friction for crack development– >1-inch thickness to level up– Greater distress requires > interlayer thickness

• Interlayers with past performance issues– PE sheeting, chip seals, slurry seal, or curing

compound, open-graded AC– Erodible/stripping, not resistant to reflective

cracks, insufficient friction

Separation Layer, con’t• Geotextile layer

– Nonwoven used for JPCP unbonded overlays

• Germany & Missouri

– Not used for CRCP, yet– If distress is high then GT

probably is not useful to stop low shear reflective crack

– Doesn’t level up surface– Durability?

Structural Design MethodsCRCP Overlays

• Darwin M-E (MEPDG)– Results in better thickness values

• IDOT– Modified-AASHTO JRCP/CRCP Method– Subtract 1-inch for overlay

• TxDOT– Traditionally, AASHTO 1993 for thickness design

5 Million ESAL’sSoil CBR or “k”

Soil CBR = 3.0

“k” = 100

100 ft Jointed = 10in.

CRCP = 8in.

CRCP 80% of Jointed

Typical Illinois DOT (2007)New CRCP Thickness Design

Thickness ESAL, Millions

8 in. 5

10 in. 20

12 in. 100

14 in. (max) 300+

•CRCP overlay design minus 1-inch

Construction Issues• Pre-overlay repairs

– Punchouts!– High severity spalling– Subgrade/Drainage problems

• Concrete Material Selection• Steel Content

– Minimum 0.60%• Interlayer provides friction

– Erodibility test of interlayer • Hamburg Test (after Zollinger et al.)

– Whitewash surface or debond base layer (?)

IDOT CRCP Unbonded OverlaysHistory

• Constructed Unbonded overlays since 1967• I-55 and I-70 (3 sections) – 1967,1970, 1974

– Unbonded CRCP overlay of JRCP• I-74 Knox County - 1995• I-88 Whiteside Country – 2000-01• I-70 Clark County – 2002• I-57/I-64 Mt. Vernon – 2011-12

I-70 CRCP Overlay Sections• CRCP Overlay (1967) – MP 31-35

– 8,7, and 6-inch CRC w/ 0.6, 0.7, & 1.0% steel• 6-inch HMA interlayer• 10-inch JRCP

– ADT = 14,000 w/ 34% trucks• 17 million (1986)

– CRS = 5.7 (1986) & R.I. = 86• 7.3% patching for 6-inch CRCP & 0% for 8-inch

– Overlaid in 1989

– Minimum req’d = 7 inches Lippert & DuBose 1988

I-55 CRCP Overlay Sections

• 8-inch CRCP Overlay (1970)– Springfield, IL (MP 89-92)– 9-inch JRCP– Steel content= 0.6%– 4 inch HMA interlayer + 8 inch HMA overlay– ADT = 24,600 w/ 15% trucks– CRS=6.5 & R.I. = 85 (1986)– Crack Spacing = 2.9 ft (1986)– Percent patching= 0.1% (1986)– Total ESALs=9.2x106

Lippert & DuBose 1988

I-55 CRCP Overlay Sectionscon’t

• 9-inch CRCP Overlay (1974)– Springfield, IL (MP 105-108)– 10-inch JRCP– Steel content= 0.6%– 4 inch HMA interlayer– ADT = 17,000 w/ 22% trucks– CRS = 7.2 & R.I. = 97 (1986)– Crack Spacing = 3.2 ft– Percent patching= 0% (1986)– Total ESALs=9.1x106

Lippert & DuBose 1988

I-74 Knox County (1995)Existing

• MP 54-62 Westbound only– East of Galesburg

• Existing pavement cross-section (1969)– 3 to 4.5 inches HMA overlay– 7-inch CRCP– 4-inch HMA base

• Severe D-cracking and punchouts– Transverse and longitudinal cracks in HMA overlay– Full-depth concrete patches

McNeal 1996; Heckel 2001

I-74 Knox County (1995)• 9-inch CRCP overlay w/ tied PCC shoulders

– Design ESALs = 24 million– Crack spacing = 3.1 ft (1997); 2.3 ft (2001)

• 2009 AADT = 14,800 (SU = 550, MU = 3300) – Annual ESALs = 1.070x106

• Condition Rating Survey (CRS) value– 8.3 out of 9.0 (2001)– 8.2 out of 9.0 (2009)

• IRI – 70 (2001); 69 (2009)• Transverse crack LTE = 92% (2001)

I-88 Whiteside County (2000-01)

• IL 78 to west of Rock Falls

• Existing 8-inch CRCP (1975)– Crushed river gravel– blowups and D-cracking problems– HMA overlays in 1988, 1991– Recurring blowups and D-cracking

I-88 Whiteside County (2000-01)

• 9.25-in CRCP unbonded overlay– 1-inch leveling binder placed on top of the

existing 3.25-inch HMA overlay

• 2010 CRS = 8.0 out of 9.0• IRI (in/mi) = 52 EB, 57 WB• 2009 AADT = 8800 (SU = 300, MU = 2300)

– Annual ESALs = 0.741x106

I-70 Clark County (2002)General Project Information

• Originally constructed in 1969• 8-inch CRCP on 4-inch HMA base• Subsequent bituminous overlays totaling 7-

3/4 inches• Traffic (2-way)

– Current ADT of 24,000 with 42% trucks• Location = IL 1 to Indiana Line

Proposed Pavement Cross Section

4” Asphalt Base

8” CRCPBITUMINOUS

SHOULDER

BITUMINOUS OVERLAYBITUMINOUS OVERLAY

MILL OR OVERLAY TO GRADE LINE

12” UNBONDED

CRCP OVERLAY

12” PCC

SHOULDERS12” PCC

SHOULD.

12 ft. 6 ft.24 ft.

IDOT CRCP Design (I-70)• Pavement design = Chapter 54 of BDE manual

– 30-year design traffic of 116x106 ESAL’s (rigid)– New design = 13-inch slab thickness

• Thickness credit of 1-inch given in areas of unbonded overlay (NCHRP/Corps of Engrs.)– 12-inch design thickness w/ 0.80% steel (#7 bars)– Nominal 5-inches of HMA interlayer– 25 bars at 6-1/4 in. centers-longitudinally– #4 bars at 2-ft. intervals-transversely

I-70 CRCP Overlay Warranty

• 5-year duration• Warranty bond required• Warrants materials and workmanship• 95% of pavements expected to not need

warranty work• Evaluated in 0.10-mile sections• Distress parameters defined in SHRP’s

“Distress ID Manual for LTPP” P-338

Warranted CRCP Distresses• Transverse and longitudinal cracking

(moderate and high severity)• IRI limited to 150 in./mi.• Spalling of longitudinal joints• Scaling• Patch deterioration• Punchouts• Corrective actions defined for each distress

I-70 Clark County (2002)Performance

• 12-inch CRCP overlay w/ HMA interlayer• 5 yr. warranty contract

– two dozen “punchouts” in 9 miles of pavement– problem (?) = 12-ft. full-depth PCC shoulders tied with

#8 bars had punchouts located at jointed shoulder.

• Overall performance very good– CRS = 8.1 (2010)

• IRI = 65 (EB); 69 (WB)• 2010 AADT = 20,500 (SU = 650, MU = 8000)

– annual ESALs = 2.55x106

I-70 CRCP Overlay

Example: Early-Age Punchout

I-57/I-64 Alternatives (2010)

• HMA overlay of existing CRCP– Rubblization with HMA– JPCP and CRCP options

• MEPDG & IDOT designs• Milling options vs. rubblization• Interlayer type• Thickness options

Poor Section I-57/I-64 NB

Good Section I-57 NB

MEPDG CRCP OverlayInputs

• 20-year design life– Mattoon-Charleston, IL Climate

• ESALs – 80x106

• A-7-6 soil type– k=200 psi/in

• Tied concrete shoulder– 40 to 80% LTE

• CRCP Steel properties – 3.5 inch depth, #6, 0.7%

MEPDG CRCP DesignResults

• New CRCP = 11 inches– HMA base unbonded = 4inches

• Unbonded CRCP = 9 inches– AC base interlayer = 2 inches– CRCP (existing) = 8 inches

• Unbonded CRCP = 10.5 inches– HMA interlayer = 1 to 2 inches– CRCP (rubblized) = 8 inches

I-57 / I-64 Mt. Vernon (2011)• Mill existing HMA overlay• Rubblize existing 8-inch CRCP• Place 3-inch HMA interlayer• 10.5-in. CRCP overlay w/ 0.7% steel

National Performance

(Smith et al. 2002)15 sections in GA, IL, ND, WI, AR, MD, PA

Performance Recommendations

• Concrete Overlay > 7 inches– Consistent with IDOT policy

• HMA Interlayer > 1-inch– Dense-graded

(Smith et al. 2002)

LTPP Database

• 4 unbonded CRCP sections

• Georgia– 20-yr– HMA Interlayer = 0.75 inch– CRCP overlay 8.25-inch– Existing section 8-inch

CRCP Overlay of JPCP in UK

• Refurbish 6.2km section of M25 London Orbital Motorway during 2000/2001

• Strengthened using hybrid solution of 200mm CRCPoverlay for most heavily loaded traffic lanes 1-2, with AC overlays for lane 3 & shoulder

• Existing 3-lane dual carriageway of un-reinforced concrete slabs with contraction joints at 5m centres– Road opened to traffic in 1979– 10mm AC OL in 1990– Large amount of pavement faulting due to underlying clay– AADT currently exceeds 120,000 vehicles approximately

15% classified as Heavy Goods Vehicles (HGV’s)

M25 London Orbital Motorway, UK

CRCP Unbonded Overlay Summary

• CRCP unbonded overlays– 7 to 12 inches– Steel content = 0.6 to 0.8%– #5 to #7 bars– design ESALs from 5 to 100x106 ESALs

• HMA interlayer– Dense-graded asphalt mixtures– >1-inch

Current I-39 Section Issue• Existing CRCP (~10in) and JPCP (11,14 in)

with materials-related distress (?)• Constructed 1989

Concrete Material Distress

CRCP Polished Section

Lankard 2012

Bibliography• Rasmussen, R., Rogers, R., Ferragut, T. (2009), Continuously Reinforced

Concrete Pavements Design and Construction Guidelines, FHWA-CRSI.• Harrington, D. et al. (2008), Guide to Concrete Overlays Sustainable Solutions for

Resurfacing and Rehabilitating Existing Pavements, National Concrete Pavement Technology Center, Iowa State University, Ames, IA.

• Smith, K.D., H. Yu, D. Peshkin, (2002), Portland Cement Concrete Overlays: State of the Technology Synthesis, Federal Highway Administration, Washington, DC.

• Lippert, D., DuBose, J. (1988), Performance Evaluation of Concrete Overlays, Physical Research Report No. 101, Bureau of Materials and Physical Research, Illinois Department of Transportation.

• McNeal, A. (1996), Planning , Design and Construction of an UnbondedConcrete Overlay, Physical Research Report No. 122, Bureau of Materials and Physical Research, Illinois Department of Transportation.

• Heckel, L.B. (2002), Performance of Unbonded Concrete Overlay on I-74, Physical Research Report No. 140, Bureau of Materials and Physical Research, Illinois Department of Transportation.

• Gagnon, J.S., Zollinger, D.G., and Tayabji, S.D. (1998), Performance of Continuously Reinforced Concrete Pavements: Volume V: Maintenance and Repair of CRC Pavements, FHWA-RD-98-101

Bibliography, con’t

• CRSI (1988), Performance of CRC Overlays: A Study of Continuously Reinforced Concrete Resurfacing Projects in Four States, 26 pp.

• CRSI (1973), Design and Construction of Continuously Reinforced Concrete Overlays, 17 pp.

• PCA (1976), Continuously Reinforced Concrete Overlay: 1975 Condition Survey, 26 pp.