Urban arterial Rural primary/interstate · 2018. 10. 8. · Concrete Overlays (1901 ... OVER POOR...
Transcript of Urban arterial Rural primary/interstate · 2018. 10. 8. · Concrete Overlays (1901 ... OVER POOR...
CONCRETE OVERLAY
PERFORMANCE
Urban arterial Rural primary/interstate
Urban freeway/interstateIntersections Rural secondary roads
Questions
• Why Concrete Overlays?
• What types?
• How much $?
• How do they perform?
Benefits of Concrete Overlays
• Cost-effective
• Extends pavement life
• Easy to maintain
1978 Grundy Co. T-55 6” Overlay (PCI = 78, IRI = 122)
Reference Documents
2014 2015
Concrete Overlays (1901 – 2012)
• 1,152 concrete overlays nationwide
• 46 states
NCHRP Syntheses 99 & 204 (1982, 1994) & ACPA National Concrete Overlay Explorer (2013a)
ACPA
National Concrete Overlay Explorer
acpa.org
ACPA
National Concrete Overlay Explorer
Iowa Concrete Overlays
Over 2,000 miles & over 400 projects
(1960 - 2015)
Bonded vs. Unbonded
Bonded Overlays (2” – 6”)
• Add structural capacity
• Fair to Good condition
• Eliminate surface distress
• One monolithic unit
Unbonded Overlays (4” – 11”)
• Restore structural capacity
• Deteriorated condition
• Eliminate surface distress
• Minor or Major rehabilitation
The When is Important…
Maintenance
Resurfacing
Reconstruction
Evaluation Steps
1. Pavement History ( Records)
2. Field Review of Distresses
3. Coring Pavement
4. Additional Field Tests
(when necessary)
5. Condition Assessment Profile
BONDED OVER ASPHALT/COMPOSITE
KEYS TO SUCCESS
• Bonding is critical
• Small square panels reduce curling,
warping, & shear stresses in bond
(spacing in feet=1.5 x thickness in inches)
• Mill to remove surface distresses, or
improve bonding
• Leave 3” to 4” of HMA after milling
• Existing asphalt pavement < 120ºF
• Application of curing compound is critical
How Do Bonded Overlays over
Asphalt Work?
• Concrete bonds to the asphalt- Lowers the neutral axis- Decreases stresses in the
concrete
• Short joint spacing- Act like paver-blocks- Requires additional saws
• Fibers improve concrete toughness
BONDED OVERLAY ON CONCRETE:
KEYS TO SUCCESS
• Thickness 2” – 5”
• Match joints
• Existing joints - fair condition or be repaired
• Trans. joints full depth +1/2” Long. Joints at T/2
• Curing should be timely and adequate
• Coefficient of Thermal Expansion (CTE)
Coefficient of Thermal Expansion (CTE)
• Overlay CTE should be similar to underlying pavement
• If not, overlay CTE should be lower than exist. pavement
• Key ☞ similar coarse aggregate type
Shear ShearOverlay
Existing Pavement
Tensile stress
Joint Design– Full Depth Cut & Width
of Cut
UNBONDED OVER ASPHALT/COMPOSITE
PAVEMENTS: KEYS TO SUCCESS
• Thickness 2” – 6”
• Milling to eliminate 2”+ surface
distortions
• Existing asphalt pavement < 120ºF
• Partial bonding is acceptable
UNBONDED OVER CONCRETE
PAVEMENTS: KEYS TO SUCCESS
•Separator layer (1” asphalt or geotextile fabric)
•Faulting of 3/8 in. or less in the existing concrete
pavement
•Shorter joint spacing minimizes curling & warping
stresses
•No need to match joints
UNBONDED OVERLAYS CAN BE PLACED
OVER POOR CONCRETE PAVEMENTS
2007
D35-Kansas City Metro 9000 ADT
5” Unbonded Overlay
Excellent Condition
Unbonded Overlays - Separation
Geotextiles
• Nonwoven fabrics
• Daylight to foreslopes
• Tie into underdrain
system
Overlay Cost Survey
• 31 projects in 7 states in 2015
• Concrete furnish, placement (finishing, jointing, curing, etc.)
• Pre-overlay repairs, separation layer (if used) not included
$0.00
$0.50
$1.00
$1.50
$2.00
$2.50
$3.00
$3.50
$4.00
$4.50
Iowa Michigan Missouri Oklahoma South Dakota Minnesota Illinois
$2.52
$2.82
$3.35 $3.35$3.58
$4.07
$4.45
Average Concrete Overlay Cost ($/SY/in.)Bonded and Unbonded Overlays
$2.52
$4.07
$3.58$3.35
$2.82
$3.35
$4.45
Concrete Overlay Design
• BCOA (ACPA 2012) http://apps.acpa.org/applibrary/BCOA/
• StreetPave (ACPA 2014)http://www.acpa.org/streetpave/
• BCOA-ME
(Vandenbossche 2013)
http://www.engineering.pitt.edu/Vandenbossche/BCOA-ME/
BCOA-ME
Macro-Fibers
IHRB TR-698 - CONCRETE OVERLAY
PERFORMANCE ON IOWA’S ROADWAYS
• How to measure performance?
• ICPA history (Dan King)
• InTrans performance data
(Dr. Smadi & Inya Nlenanya)
• Data Analysis
(Dr. Ceylan & Yu-an Chen)
PERFORMANCE
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BCOC 4%
UBCOC34%
BCOA45%
UBCOA17%
Percent of Data (based on length)
PCI Good to Excellent = 86%IRI Below 170 in./mi. = 92%
PCI Good to Excellent = 85%IRI Below 170 in./mi. = 89%
PCI Good to Excellent = 95%IRI Below 170 in./mi. = 88%
PCI Good to Excellent = 68%IRI Below 170 in./mi. = 92%
TR-698 SUMMARY
Whitetopping
NOTE: BCOA 6” AND UNDER CONSIDERED IN BONDED CATEGORY
PCI (%)
Concrete
overlay:
Percent of
data based on
number of
projects (%)
BCOC:
Percent of
data based
on number of
projects (%)
UBCOC:
Percent of data
based on
number of
projects (%)
BCOA:
Percent of
data based
on number of
projects (%)
UBCOA:
Percent of
data based
on number
of projects
(%)
100-81
(Excellent)55 21 46 60 66
80-61 (Good) 31 47 39 26 29
60-41 (Fair) 8 26 7 9 4
40-21 (Poor) 5 6 7 5 1
20-0 (Very poor) 1 0 1 0 0
Total 100 100 100 100 100
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Total number of data points: 1,249Total number of projects: 387
PCI DISTRIBUTION
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IRI (in/mile)
Concrete
overlay:
Percent of
data based on
number of
projects (%)
BCOC:
Percent of
data based on
number of
projects (%)
UBCOC:
Percent of
data based on
number of
projects (%)
BCOA:
Percent of
data based on
number of
projects (%)
UBCOA:
Percent of
data based on
number of
projects (%)
< 95 (Good)
40 54 33 42 43
96-169(Average)
51 38 56 50 45
> 170 (Poor)
9 8 11 8 11
Total 100 100 100 100 100
Total number of data points: 1,249Total number of projects: 387
IRI DISTRIBUTION
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ADT (count) Percent of data basedon number of projects
(%)
<500 32
501–1,000 34
1,001–1,500 16
1,501–2,000 5
2,001–3,000 5
3,001–4,000 2
4,001–10,000 4
> 10,000 2
Total 100
ADT DISTRIBUTION
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Total number of data points: 1,249Total number of
projects: 387
Excellent
Fair
Poor
Very Poor
Good
PCI vs AGE ENTIRE DATABASE
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Total number of data points: 1,249Total number of
projects: 387
170 in./mi
IRI vs AGE ENTIRE DATABASE
22
67.461.2 64.4 63.5
74.679.8 83.0
78.474.2
0
10
20
30
40
50
60
70
80
90
100
1960-1969 1970-1980 1981-1985 1986-1990 1991-1995 1996-2000 2001-2005 2006-2010 2011-2015 TOTAL
Average PCI by Age of Overlay
220.0
136.5147.0
136.6 140.2127.0
112.093.0
110.0 118.0
0.0
50.0
100.0
150.0
200.0
250.0
1960-1969 1970-1980 1981-1985 1986-1990 1991-1995 1996-2000 2001-2005 2006-2010 2011-2015 TOTAL
Average IRI by Age of Overlay
6” Concrete Overlay on asphalt
490 ADT
20’ transverse joint spacing
PCI = 72, IRI = 115
1977 Boone R-18
1977 Washington County W-55
6” Concrete Overlay on asphalt
1360 ADT
15’ transverse joint spacing
PCI = 78, IRI = 122
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• Analytical Investigation &
Field Investigation Plans
• Field Investigation
• Develop Phase II Research Plan
• Phase I Final Report
WHAT’S NEXT: OVERLAY JOINT
SPACING
Questions
www.cptechcenter.org