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6/08/2013
1
Concrete Pavements Conference 201312 August 2013
US Precast Concrete Pavement
Technology & Directions
Shiraz Tayabji
Applied Research Associates, Inc.
Elkridge, Maryland
Presentation Outline
� Precast concrete pavement (PCP) background
� US PCP applications & systems
� US experience todate
� Technical considerations
� Case studies
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Preamble
The research objective of the recently completed SHRP 2 highway renewal area was to achieve highway system renewal that is performed rapidly, causes minimum disruption, and produces long-lived facilities.
A tactic for rapid renewal is to minimize field fabrication effort and speed the on-site construction phase of the work that actually impacts traffic. However, shorter facility life spans cannot be accepted as the
price of rapid renewal.
Rapid renewal and longer service life can be achieved using precast concrete pavements
This presentation provides an update on the US precast concrete pavement technology based on a SHRP2 study and other on-going US
activities
ASCP Concrete Pavements Conference 2013
Precast Concrete Pavement Background
� A recent technology – production use in US since 2001
� Used primarily for RAPID repair & rehabilitation &
longer-lasting treatments
� Typically, night-time work & short work windows
� Typically, repair/rehab along a single lane
� Multiple-lane repair/rehab possible based on site constraints
� Typical production rates/closure
� 15 to 20 repairs
� 30 to 40 panels for continuous jointed PCP (up to 200 m)
� Up to 200 m for prestressed PCP
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Precast Concrete Pavement Applications
ASCP Concrete Pavements Conference 2013
Intermittent repair along a section of I-295 in New Jersey
Precast Concrete Pavement Applications
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Placement of jointed precast
concrete panels in
Minnesota.
Outside lane and shoulder
replaced with precast prestressed
concrete pavement in Delaware.
Precast Concrete Pavement Applications
Placement of a
precast concrete
panel spanning two
traffic lanes on I-66
in Virginia.
Four lanes (including
outside rush-hour
shoulder lane) replaced
with precast prestressed
concrete panels on I-66
in Virginia.
Precast Concrete Pavement Applications
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Post-tensioning a series of 11 m long x 3.65 m wide panels on I-680 in California
Precast Concrete Pavement Applications
Lane Closure Requirements
� An over-riding assumption for use of PCP
is that some level of traffic operation will be
maintained
� Single-lane repair/rehab – need at least a two-
lane closure & at least one lane for traffic
� Two-lane repair/rehab – need at least a three-
lane closure & at least one lane for traffic
� Otherwise, intermittent full traffic stoppage
may be necessary (not preferred)
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� For intermittent repairs
� Nominally reinforced panels
� Prestressed (pretensioned) panels
� For continuous Applications
� Jointed PCP systems (JPrCP)
� Nominally reinforced panels
� Prestressed (pretensioned) panels
� Post-tensioned systems (PPCP) - fewer
active joints; longer sections
� Incrementally connected PCP (ICPCP)
� Simulates JRCP: intermediate joints
locked-up
� Fewer active joints; < 30 m long sections
Precast Pavement Applications
ASCP Concrete Pavements Conference 2013
� Precast prestressed pavement (Texas system)� Non-proprietary (FHWA sponsored)
� Precast jointed pavement� Non-proprietary
� Michigan system (FHWA sponsored)
� Illinois Tollway, etc.
� Proprietary/Vendor-Specific� Fort Miller system
� Roman Stone
� Other
� System components – Off-the-shelf or proprietary
Precast Concrete Pavement Systems
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PCP Systems in Use (USA)
ASCP Concrete Pavements Conference 2013
Intermittent Repair
Conventional Jointed PCP System
PPCP Systems – Variable width (3.65+ m), variable length (3 to 11 m used todate) (in use in Indonesia also)
PCP Systems in Use (USA) - Posttensioned
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Current State of PracticeThe Posttensioned System ( U of Texas Developed)
Current State of Practice
Roman Stone System Michigan System Fort Miller System
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Current State of Practice
The Kwik Slab SystemThe PANY System
LaGuardia Airport, NY
The Illinois Tollway System
� Heavily-traveled main line interstate/primary system & urban roadways� Huge need on aging interstates built 40 – 50 years ago� The very best place to use premium repair material
� Interstate/primary system & urban ramps� Often no alternative routes and heavy traffic
� Intersections� Some can not be closed
� Bridge approach slabs� A large no. of approach slabs across country need to be rehabilitated
� Bus pads� Where alternative bus stop locations are not acceptable
Where to Use Precast Pavement?
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� US/Canada
� Production use
� CA, IL Tollway, IA, NJ, NY, UT, VA
� Ontario, Quebec
� Demos
� CO, DE, FL, GA, HI, MI, MN, MO, NV, OH, PA, TX,
WI
� Airfield
� PANY/NJ, Dulles airport, USAF
Precast Pavements - Users
ASCP Concrete Pavements Conference 2013
� Canada – Based on US practices
� The Netherlands – The ModieSlab system
� Japan - for highway, airport and tunnels
� Russia (Soviet Union) - precast pavements for airfields & highways
� France - Removable hexagonal panels in urban areas
� Indonesia - New PPCP construction (rural – 35 km & more)
International PCP Practices
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Structural Design Considerations
� Intermittent repairs (Service life > 15 to 20+ years)� Same or a little less thick panels as existing PCCP
� Generally higher strength concrete & reinforcement
� Continuous jointed (Long-life; > 30 to 40+ years)� Depending on traffic, panels need to be same thickness as
new slab or 25 to 50 mm less
� Generally higher strength concrete & reinforcement
� Continuous prestressed (Long-life; > 30 to 40+ years)� Panels 75 to 100 mm less than new slab (using at least 1.4
MPa effective prestress at midsection)
� Prestress system design need to be developed (strand diam. & spacing =>postensioned section length)
� Expansion joint design
ASCP Concrete Pavements Conference 2013
� Constructability (as affected by system
design & site conditions)
� Concrete durability (not an issue)
� Pavement performance, as affected by
� Load transfer at joints
� Panel support condition
Key PCP Technical Considerations
ASCP Concrete Pavements Conference 2013
PCPs ARE NOT “SUPER” PAVEMENTS; ONCE INSTALLED, PCPs
BEHAVE SIMILAR TO CONVENTIONAL CONCRETE PAVEMENTS.
�Only the method of construction is different
THE CONCRETE & THE PANELS CAN BE VERY DURABLE
However, uniform support condition & good load transfer at joints
are critical
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� For repairs� Method 1: Dowels are drilled and epoxy-grouted along existing pavement sides of joint & dowel slots in panel
� Method 2: Dowels embedded in the panel & dowel slots cut in existing pavement
� Method 3: Dowel slots cut in panel & existing pavement
� For continuous applications:� Dowels embedded along one side of the panels & dowel slots at other side of the panel (top or bottom)
� Dowel slots along both sides of the panels
Joint Load Transfer Considerations
ASCP Concrete Pavements Conference 2013
� Use of existing base
� Granular� Reworked, compacted & regraded
� Reworked, compacted, regraded & bedding material applied
� Stabilized� Used as is or trimmed; bedding material applied
� Bedding material� < 6 mm fine-grained granular material
� Thicker layer of RSFF or polyurethane grout
� New base – granular or rapid-setting LCB
Panel Support Considerations
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� Compaction testing typically not performed on
finished granular base/bedding; moisture control not
attempted
� Use of LWD is recommended for compaction monitoring
� Granular base/bedding trimming is time consuming,
requiring multiple passes (need a rapid auto-grading
system)
Panel Support Issues
ASCP Concrete Pavements Conference 2013
Installation of Precast Panels
� Site survey – identify needed panel dimensions
� Fabricating precast panels at plant
� Transporting panels to the site
� Removal of old pavement
� Preparing base/subbase
� Installing panels on finished base
� Interconnecting panels using dowel/slot system
� Post-tensioning panels (design option)
� Grouting dowel/tie-bar slots (design option)
� Injecting bedding grout to firmly seat panels (design option)
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Repair Panel Installation Options
Existing Slab Existing Slab
Existing Base
Precast Panel
Prepared bedding (Granular or
flowable concrete)
Existing Slab Existing Slab
Existing Base
Precast Panel
Rapid-setting grout or polyurethane Adjustable Beam
� SHRP2 Project R05 deflection testing indicate good load transfer and good deflection response at transverse joints of JPrCP systems used for repair and continuous applications.
� The PPCP systems exhibited higher deflections and lower load transfer at the expansion joints. However, since these expansion joints are 50 to 80 m apart, the potential for significant joint related distress is low.
� The behavior and performance of the constructed PCP systems appear to be similar to that of like cast-in-place concrete pavements.
Findings Based on Field Testing
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� Cost continues to be an issue
� Base treatment & bedding use
� On-site QA/QC focus
� Availability of local precasters interested in
this market needs improvement
o Expected to improve as market size increases
� Proprietary products issue
� Limited competition in the marketplace
� Agency/contractor staff training
Continuing Issues to be Addressed
ASCP Concrete Pavements Conference 2013
� PCP technology is a mature, but still evolving, technology that shows great potential for rapid repair and rehabilitation of existing pavements
� Although experience with PCP systems is limited, less than 14 years, performance todate indicate that well-designed and well-constructed PCP systems can be expected to provide long-term service
Summary
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Thank [email protected]
� Project detailso Precast pavement system: Fort Miller’s Super Slab system
o Panel thickness: 8.75 in. (existing JRCP thickness – 9 in.)
o Panel dimensions: length – variable (8, 10, 12 ft); Width – 12 ft
o Number of panels installed: 277
o Base: existing sandy granular base
o Joints: Doweled transverse joints; longitudinal joints not tied
o Traffic level: Heavy freeway traffic with heavy truck volume
(140,000 vpd)
o Existing JRCP joint spacing: 78 ft
� Performance – good (May 2010)
NJ I-295 - Repair (2008)
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NJ I-295 (June 2008) Intermittent Repairs using the Super Slab System
�Process:o Sawcut repair boundaries in advance
o Night of repair – remove damaged panel; prepare base; drill dowel holes in existing panels; insert dowel bars; install precast panel
o Next night – patch dowel slots; underseal panel
33
NJ I-295 (June 2008) Intermittent Repairs
NEXT
NIGHT
����
34
FIRTST NIGHT
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NYS I-495, Near JFK Airport (2011) Intermittent Repairs using the Roman Road System
� Details:o 4 miles (both directions) full depth repairs
o Over 800 panels – Panels mostly 8 ft long by 12 ft wide, some 10 ft long; t = 9 in.
o Bedding: Uretek HD polyurethane foam
o Load transfer: Full DBR
o Traffic: 200,000 vpd
� Process:o Mill existing AC overlay
o Sawcut repair boundaries in advance
o Night of repair – remove damaged panel; prepare base; install precast panel; inject urethane foam to raise panel
o Next night – Cut dowel slots; install dowel bars (DBR)
� Performance - Good
35
NYS I-495, Near JFK Airport (2011) Intermittent Repairs using the Roman Road System
Installation under Heavy
Traffic – at Night 36
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� Project detailso Precast pavement system: Fort Miller’s Super Slab system
o Panel thickness: 10 in.
o Panel dimensions: length –18 ft; Width – 10 ft (toll plaza drive lanes; 12 lanes)
o Number of panels installed: 1,071
o Base: existing granular base (top 2 in. removed) with 1.5 in. leveling stone dust
o Joints: Doweled transverse joints; longitudinal joints tied
o Total project area: over 40,000 y2 (both sides of the toll booths)
o Traffic level: Heavy commuter traffic (New York city area) with large number of trucks per day (eastbound through toll plaza -72,000 vpd)
� Performance - Good
Tappan Zee Jointed (Oldest - 2001)
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Tappan Zee Jointed (Oldest - 2001)
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� Project detailso Precast pavement system: Fort Miller’s Super Slab system
o Panel thickness: 8.75 in.
o Panel dimensions: length – 15 ft (a few shorter panels to accommodate ramp curvature); Width – 12 ft
o Number of panels installed: 224
o Base: existing gran. base with up to 0.25 in. leveling stone dust
o Joints: Doweled transverse joints; inside longitudinal joint (ramp centerline joint) tied to existing JRCP
o Total project length: 3,552 ft
o Traffic level: Moderate commuter traffic (Washington, DC area) with low level of truck traffic (55,000 vpd)
� Performance – Good (some cracking)
Virginia Jointed (2009)
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Virginia Jointed (2009)
40
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� Project detailso Panel thickness: 8.75 in.
o Panel dimensions: length – 10 ft; Width – 12 ft (two inside lanes) and 27 ft (two 12 ft outside lanes and 3 ft shoulder). Base: existing aggregate with up to 0.5 in. leveling stone dust
o Subbase: 6 in. cement stabilized subgrade
o Panel/base interface: geotextile fabric
o No. of panels post-tensioned together: 11 (end segments) or 16
o Post-tensioning method: from expansion joints
o Total project length: 1,020 ft; Total no. of expansion joints: 8
o Traffic level: Heavy commuter traffic (Washington, DC area) with large no. of trucks per day (184,000 vpd with 5% trucks)
� Performance - Good
Virginia PPCP (2009)
Virginia PPCP (2009)
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• Thousands of distressed approach slabs exist– Exhibited by classic “bump” at bridge end/approach
• Causes of failure – Settlement of underlying soils
– Erosion of embankment materials
• Difficult to replace – Limited room for staging – narrow shoulders
– Often repaired with “band-aid” materials
• Precast panels - a good fast and permanent repair– Full-depth replacement allows opportunity to repair underlying embankment
– Can be installed in over night or over-the-weekend work windows
Bridge Approach Slabs
NY State DOTNY State DOT
Example: Approach Slab on Existing Bridge Abutments
Cross Section at End of Existing Bridge
Placing panel Over Anchor Rods
Placing panels In One Lane
Source: The Fort Miller Co., Inc.