Concrete Pavement Overlays
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Concrete Pavement Overlays
36th Annual Mid-Atlantic QualityAssurance Workshop
Charleston, WV
February 12, 2003
Robert R. Long Jr.Regional Director
American Concrete Pavement Association
Northeast Chapter
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Family of Concrete Overlays
BondedConcrete
Overlay
UnbondedConcrete
Overlay
Existing PavementConcrete
ConventionalWhitetopping
Overlay
Ultra-ThinWhitetopping
Overlay
ConcreteOverlays
Existing PavementAsphal t
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Concrete Pavement Types
Jointed Plain
Undoweled
Doweled
Jointed Reinforced
Continuously Reinforced
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Bonded Concrete Overlay
Consists of a thin concrete layer (100 mm or less)on top of an existing concrete surface.
Specific steps are taken to bond the new concreteoverlay to the existing concrete.
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Bond = Strength
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Bonded Concrete Overlay
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History First bonded PCC resurfacing
Warsaw Street in Toledo, Ohio in 1913.
Used to correct construction deficiencies relating to a frozenpavement.
Typical applications have been:
to correct construction deficiencies to correct surface problems relating to wear or loss of skidresistance
to repair damage caused by chemical spills.
In recent years, used to improve load-carrying
capability where feasible to change the grade.
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Advantages
Increase structural capacity. More efficient than AC.
One in. of PCC ~ two in. of AC
Critical edge stresses are
about 35% lower than an
equivalent asphalt overlay. Long service life
High PSI.
Lower user & engineeringcosts.
Rut free100
140
180
220
260
300
0 2 4 6 8
Overlay Thickness (in.)
Edge
Stre
ss
(psi)
Bonded
PCC Overlay
AC Overlay
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Applicability
Condition of underlyingpavement dictates thefeasibility...
But you must consider pre-overlay repair.
Do NOT apply to appreciably distressed
pavements.
pavements with high-severity"D" cracking or reactive
aggregate problems.
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Pre-Overlay Repair
Not all transversecracks require repair.
Address working
cracks (faulting,pumpingcorner breaks)
Full-depth repair.
Random crack control.
NOTE: Untreated c racks wil l eventual ly ref lect
through . Saw & seal the cracks
Transverse Cracks
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Placed and Tacked Directlyonto Pavement Surface
-OR-Mounted on Chairs
Recessing Bars
2 inches Cover
Milled
Placement of Crack Control Cages
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Placement of Crack Control Cages
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Pre-Overlay Repair
Spalling, blow-ups, cornerbreaks.
Repair Full or Partial Depth
Lightly spalled joints may be
milled to sound concrete. Depressions less than 2 in. deep,
fill with concrete during the overlay
operation.
Depressions more than 2 in. deep,
fill with concrete prior to the
overlay.
Joint Deterioration
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Bonding
Bonding between the two layers isprincipally a mechanical process
Depends primarily on the soundness and
cleanliness of the underlying pavement. Full Bond
Bond shear strength = 200 psi (min.)
Is grout required to enhance bonding?
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Bonded Concrete Overlay
Cleanliness is key to long-term performance.
Surface preparation procedures:
Shotblasting
Milling
Surface Preparation
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Bonded Concrete Overlay
Shotblasting
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Bonded Overlays
Milling
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Bonded Overlays
Milling
Shotblasting
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Bonded Overlays
SurfaceCleaning
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Bonded Concrete Overlay
0
100
200
300
400
500
600
ShearStren
gth(psi)
Milled/Grout Milled/None Shot
blast/Grout
Shot
blast/None
Corner Center Edge Average
Grout or No-grout?
Unpublished Research Data: University of Texa
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Curing
Bonded Overlays
Critical because high ratioof surface area to volumeof concrete.
Apply ASAP
1 gallon/100 sq.ft.
Coat all exposed edges.
Avoid extreme weather.
Avoid contact with
prepared surfaces.
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Bonded Concrete Overlay
Good when:
Placed correctly and at the right time.
Poor when: Placed on deteriorated pavements.
Loss of bond does not necessarilyconstitute failure.
Performance
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Early Performance Studies
Gillette 1965 Included 10 overlays placed between 1954 - 1963. Adequate performance can be expected regardless of
the thickness of the resurfacing and the type offrequency of traffic
Gausman 1980 Overlays in seven states, built between 1973 -1975.
Overlays can be effectively bonded to clean pavements ingood condition.
Quality of surface preparation is critical
Bond can be retained without bonding grout.
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Other Performance Studies
Peshkin and Mueller - 1990 Study of 10 thin-bonded overlays constructed between
1976 1985.
Thickness ranged from 2 5 in.
All were jointed resurfacing of jointed original pavement.
Found mixed success.
Some projects failed in relatively few years
Others carried more than the anticipated traffic and were
performing well.
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Unbonded Concrete Overlay
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Consists of thick concrete layer (125 mm or greater)on top of an existing concrete.
Uses a separation interlayer to separate newoverlay and existing concrete.
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Unbonded Overlay
When to Use Unbonded
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When to Use UnbondedOverlays
Little or no remaining structural life
Extensive and severe durability distress
Medium to very heavy truck traffic Very weak or wet subgrade
Other obstacles to reconstruction
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Benefits
Unbonded Overlay
Little pre-overlay repair needed
Improved Structural Capacity. Very Strong Base that can maintain traffic
Reduced Faulting, Pumping, & Loss of Support
Can place on pavement in bad condition. i.e. "D" cracked pavements, ASR, etc.
No future reflective cracking.
Avoids reconstruction problems
Less construction time
What types of UBOLs and existing
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Existing Pavement Type
JPCP JRCP CRCP AC/PCC
JPCP
JRCP
CRCP
What types of UBOLs and existingpavements are compatible?
UBOLType
What types of UBOLs and existing
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Existing Pavement Type
JPCP JRCP CRCP AC/PCC
JPCP JRCP
CRCP
What types of UBOLs and existingpavements are compatible?
UBOLType
Unbonded Overlay
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Unbonded OverlayPreoverlay Repair
Unbonded Overlays are less sensitive to underlying
pavement condition than any other Overlay type
May be needed:
Repair/replace shattered or rocking slabsRepair punchouts in CRCP
Probably not needed:
Repair of other slab cracking
Repair of joint spalling
Load transfer restoration
Unbonded Overlay
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Joint Deterioration
Unbonded OverlayPreoverlay Repair
Remove Loose Materialat Mediumto High Severity Spalls(Cold Milling).
Place Cold Patch if ThinInterlayer.
What about Fracturing the
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What about Fracturing theExisting Slab
If you can fracture anexisting concrete slab and
place an AC overlay
why cant you place an
AC leveling course & an
unbonded PCC overlay?
A few UBOLs of rubblized
PCC have been built
But is the extra expense ofrubblizing justified?
U b d d C t O l
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Unbonded Concrete Overlay
Allows layers to actindependently.
Prevents distresses fromreflecting into overlay.
Materials that work:
Asphalt concrete
Some surface treatments
Materials that do not:
Polyethylene
Roofing paper
Curing compound
Separation Interlayer:
U b d d O l
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Unbonded Overlays
Can also use existingAC overlay asinterlayer
Separation Interlayer:
U b d d C t O l
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Unbonded Concrete Overlay
Separation Interlayer:
Overlay
Old Pavement
Key
Overlay
Old Pavement
Smooth Slip Plane
Thick Interlayer (> 50 mm)
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Unbonded Concrete Overlay
Whitewash Prevent heat build-up
by reflecting
heat/energy
Temperature reductionas much as 11C
(20F)
Typically lime slurry or
curing compound
U b d d O l
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Jointing
Unbonded Overlays
Mismatch joints.
Saw joints d/3.
3 FT.3 FT.
Overlay joints should bemismatched from working cracks too
U b d d C t O l
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Unbonded Concrete Overlay
Very Good
Can be expected to perform for 20+ years.
Most failures are due to the use of inadequateseparation layers.
Performance
U b d d C t O l
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Unbonded Concrete Overlay
NCHRP Synthesis 99, 1983
NCHRP Synthesis 204, 1994
NCHRP Report 415, 1999
Performance
JPC U b d d O l
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0
2
4
6
8
10
12
14
0 20 40 60 80 100
Year Built
UBOLThickn
ess(inches)
Thicknesses and Years Built
No. Projects built = 105
No Projects taken out of service = 4
Avg age when taken out of service = 20.4 yr
JPC Unbonded Overlay
JRC U b d d O l
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0
2
4
6
8
10
12
0 20 40 60 80 100
Year Built
UBOLThickn
ess(inches)
Thicknesses and Years Built
No. Projects built = 60
No Projects taken out of service = 13
Avg age when taken out of service = 22.8 yr
JRC Unbonded Overlay
CRC U b d d O l
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0
2
4
6
8
10
12
0 20 40 60 80 100
Year Built
UBOLThickn
ess(inches)
Thicknesses and Years Built
No. Projects built = 31
No Projects taken out of service = 0
Avg age when taken out of service = NA
CRC Unbonded Overlay
Concrete Overlays of Asphalt
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Whitetopping
y p(Whitetopping)
Consists of a thick concrete layer (100 mm or greater)placed directly on top of an asphalt concrete pavement.
Behaves as a new pavement on a strong base.
UTW Whitetopping
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UTW Whitetopping
Whitetopping:
Well-established, proven pavement
rehabilitation technique
Ultrathin Whitetopping:
Newer technology
Still under evaluation by some
Whitetopping History
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Whitetopping - History
First Whitetopping South 7th street in Terre Haute, Indiana - 1918
Existing flexible pavement was overlaid with 3 - 4in. of reinforced concrete
During 40s and 50s -Used to upgrade military & civil airports
Highway use
Started approx. 1960
Types have included JPCP, JRCP, CRCP, FRC
Whitetopping Use by State
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Whitetopping Use by State1992
0
1
2 - 5
6 - 10
11 - 20
> 50NCHRP Report 204
1992
Whitetopping by Pavement Type
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Whitetopping by Pavement Type
85% of projects arejointed, plain concretepavements (JPCP)
CRCP - 7.3%
FRC - 4.5% JRCP - 3.2% N
um
ber
JPCP JRCP CRCP FRC0
20
40
6080
100
120
140
160
JPCP JRCP CRCP FRC
Type of Overlay
Whitetopping Advantages
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Whitetopping - Advantages
Construction
Can place onpavement in badcondition.
Little or no pre-overlayrepair needed.
Avoid reconstructionproblems.
Minimal rain delays.
Maintain traffic on
existing surface.
Whitetopping Advantages
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Whitetopping - Advantages
Improved structural capacity.
Reacts structurally as if on
strong base course.
Maintains high level of
serviceability. Concrete slabs bridge
problems asphalt cannot.
Reduced potential forpumping, faulting
and loss of support.
Structural
Whitetopping Construction
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Whitetopping Construction
Critical issue is uniform support Subgrade / base failures need repair
Need to evaluate drainage (esp. Inlays)
Address surface distortions Direct application
Profile milling
Leveling course
Whitetopping Construction
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Whitetopping Construction
Pre-overlay PreparationOther Factors
Joint Sawing Depth
Cost ComparisonDrainage
Sweep Surface
Crack filler
Repair Performed
None
Milling or Leveling
Milling?
None
None
NoneNone
NoneNone
Distress
Rutting (< 2 in.)
Rutting (> 2 in.)
Shoving
Raveling
Trans. Cracking
Block CrackingAlligator Cracking
Long CrackingBleeding
Whitetopping Construction
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Whitetopping Construction
Direct Application Sweep surface and place
Use when rutting < 50 mm
On crowned roadways makes
thickened edges
Economical, practical.
Surface cross-section survey.
Determine cross-sectional area
& overlay volume.
Concrete overlay fills ruts.
Whitetopping Construction
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Whitetopping Construction
Transverse Cracks
Overlay
Old Pavement
Key
Overlay
Smooth Slip Plane
Old Pavement
Whitetopping Construction
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Whitetopping Construction
Profile Milling Use when rutting > 50 mm
Removes between 25 and
75 mm
Can shave off top of ruts
Used with inlays Limited vertical clearances
Single lane replacement
Whitetopping Construction
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Whitetopping Construction
Leveling Course Consider only where extreme rutting or
distortion exists
Use when rutting > 50 mm
Places between 25 and 50 mm of AC Can just fill ruts
Requires more equipment, materials, time
Usually most expensive option
Whitetopping Construction
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Whitewash
Whitetopping Construction
Apply if surface > 110degrees F.
Prevents heat build-up
or Excessive mixtemperatures.
Maintains hard pavingsurface.
Most critical for leveling
course
Whitetopping Overlays
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Joint depth (D/3).
Adjust if vary over 1 inch of nominal thickness.
D
+ 1 inchD/3
Whitetopping Overlays
Jointing
Whitetopping Overlays
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Whitetopping Overlays
Most projects are too new to provide data
Approximately 78 projects before 1982
Over 100 new projects between 1982 and 1992
Used to combat rutting in heavy truck corridors Those that are old enough are providing excellent
performance
Oldest in-service project built 1956(Columbus AFB, Miss.)
Performance
Whitetopping Overlays
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Whitetopping Overlays
US 1 - Daytona Beach, FL. Built in 1987
19 test sections -150, 175, 200 mm thick
10 year design
After 14 years service - Excellent Condition
No sign of anticipated early deterioration
High bonding between AC and PCC
AC companion sections have been resurfaced twice
Performance
Inlay Whitetopping Performance
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y pp g
Have had good to poor performance
Poor performance results from:
Poor drainage
Bathtub sections Poor load transfer
Performance
Inlay Whitetopping Performance
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y pp g
I-5 Portland, Oregon Built between 1971 and
1975
330 mm thick CRCP
Used in truck lanes
Excellent performance
Performance
Inlay Whitetopping Performance
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y pp g
I-70 Sherman Co., Kansas Built in 1983 and 1985
200 mm thick - No dowels
After about 3 years of service
3 mm of faulting
Some long. cracking, pumping, & corner breaks
Absence of dowels and bathtub section
contributed to distress development
Performance
Ultra-Thin Whitetopping
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pp g
A concrete overlay, 2 to 4 inches thick withclose joint spacing, bonded to the existingasphalt pavement.
May or may not contain fibers
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Performance Evaluation
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Ten UTW projects in Tennessee & Georgia Some of first projects in U.S..
Concrete of similar mixture proportions
Relatively close proximity
Roads of similar use (except one)
Minimal traffic control during surveys
Pavement Condition Index (PCI)
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( )
Numerical Rating from 0 to 100 -- 85-100 Excellent
70-84 Very Good
55-69 Good
40-55 Fair
25-39 Poor
10-24 Very Poor
0-9 Failed
UTW Condition Survey
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Belvoir Ave - Chattanooga, TN
Green Street - Athens, TN
Highway 56 - McMinnville, TN
Concord Road - Knoxville, TN
Cusick Street (out), Maryville, TN
Cusick Street (in), Maryville, TN
Weigh Station (app.)- No. GA
Weigh Station (leave)- No. GA
Wesley Chapel - Dekalb Co., GAMarbut Rd. - Dekalb Co., GA
1993 76 76 77
1994 85 83 83
1993 91 86 79
1992 96 94 95
1993 93 89 87
1993 75 71 72
1993 97 97 97
1993 95 93 93
1993 85 82 901993 95 91 79
Project
Year
Const.PCI
1994
PCI
1995
PCI
1999
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One Final Note
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For concrete resurfacing, payment should be:
Cubic Yard Square Yard
NOTE: Divided payment is the most
equitable and economic.
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Any Questions ?