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Presented to:
By:
Date:
Federal AviationAdministration
National Airport Pavement Test Facility Update
Airport Pavement Working Group
Don Barbagallo
April 24, 2012
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Airport Pavement Working GroupApr 24, 2012
Acknowledgement
• This presentation overview represents the work of many individuals including:– FAA Pavement Group– SRA International– Gemini Technology– McQueen Associates
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Airport Pavement Working GroupApr 24, 2012
Current Ongoing Projects at NAPTF• Construction Cycle 5 (Flexible Pavement).• Construction Cycle 6 (Rigid Pavement).• High Tire Pressure Testing on HMA.• Reflective Cracking of HMA Overlay Testing.• Alkali-Silica Reactivity Slabs.• Single Wheel Module Instrumentation.• Engineered Material Arresting System (EMAS)
Testing.• Runway Friction Test. • Upgrades to the Test Vehicle.• Future Tests.
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Airport Pavement Working GroupApr 24, 2012
Post Traffic Testing
• CC5 examines the effect of multiple gear configurations on low strength subgrade flexible pavement life.
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Airport Pavement Working GroupApr 24, 2012
CC5 TRENCH AREA
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Airport Pavement Working GroupApr 24, 2012
CC5 TRENCH SUBGRADE CHARACTERIZATION
Nuclear Density LWD
CBR Measurement Profiles
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Airport Pavement Working GroupApr 24, 2012
Preliminary CC 5 Trench Findings
CBR Summary
0
5
10
15
20
25
30
3.0 3.5 4.0 4.5 5.0 5.5 6.0
De
pth
fro
m T
op
of
Su
bg
rad
e
CBR
Average CBRin Dupont Clay Post Traffic Subgrade
Series1
Pre-
Traffi
c CBR
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Airport Pavement Working GroupApr 24, 2012
CC 6 Rigid Pavement• CC6 tests to determine the effect of concrete flexural strength
on rigid pavement life (AC 150/5320-6E) specification.
North
Asphalt Stabilized Base
South
Econocrete Base
MRS 1 = 500 psi TFS Total Passes = 17,500 @ 45K
MRS 2 = 750 psi TFS Total Passes = 20,000 @ 45 + 13,529 @ 52K + 5,200 @70K
MRS 3 = 1000 psi TFS Total Passes = 20,000 @ 45K + 11,000 @ 52K + 7,729 @ 70K
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Airport Pavement Working GroupApr 24, 2012
CC6 Rigid Pavement Tests
• Dr. David Brill & Mr. Josh Davis will present update on CC6 testing.
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Airport Pavement Working GroupApr 24, 2012
HMA High Tire Pressure Tests
• Ran tests over the winter of 2010/11.• Rutting failure in the PG 64-22 mix.• Will continue testing the PG 76-22 mix
at 17 ºF higher temperature than for the PG 64-22 mix.– High temperature can only be achieved during
the summer.– Delayed because of CC6 testing.– Plan to partially groove section of heated
pavement vs unheated pavement.
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Airport Pavement Working GroupApr 24, 2012
Reflective Cracking Test Rig
• Goal: Develop design guidance for asphalt overlay of concrete pavements based upon full scale testing.
• AC 150/5320 - 6D purely empirical solution• AC 150/5320 – 6E FAARFIELD does not address
problem.
• Cracking of asphalt overlays is a complex problem.– Environmental temperature expansion/contraction.– Thermal induced warping– Load induced fatigue
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Airport Pavement Working GroupApr 24, 2012
Reflective Cracking Test Rig
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Airport Pavement Working GroupApr 24, 2012
Reflective Cracking Test Rig• Environmental temperature change
simulation. – Interface temperature 32F– Movement = Sinusoidal 0 to 15 mils– Total Cycle Time = 6 minutes– Total # of cycles completed to date ≈ 2600
• Instrumentation includes:– Strain gages: concrete, asphalt, and surface – LVDT’s measuring concrete movement– Thermistors
• Crack length monitored with photos.• Dr. Hao Lin of Gemini Technologies will
present data.
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Airport Pavement Working GroupApr 24, 2012
Alkali-Silica Reactivity Testing
• Indoor, outdoor, & control slabs.• Periodic dosing with potassium acetate solution whenever
slabs dry out; about every 6 - 8 weeks.• On–going testing of slabs continues with little visual
evidence of ASR. • Planned grooving of slabs to expose aggregate to
potassium acetate.
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Airport Pavement Working GroupApr 24, 2012
Single Wheel Module Instrumentation
Bending, Shear, & Torque Strain Gages Wheel Encoder
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Airport Pavement Working GroupApr 24, 2012
EMAS Testing• Work performed under a CRDA between the FAA
and Zodiac Aerospace (formerly ESCO).• Comparison testing of new block design.• Additional tests planned for May 2012.
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Airport Pavement Working GroupApr 24, 2012
Aircraft Tire Friction Braking Testing
• Measure forces and friction coefficient for snow covered surface.
• Single wheel module with locked wheel
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Airport Pavement Working GroupApr 24, 2012
Aircraft Tire Friction Strain Gage
Ave Horizontal Force
Sliding Friction Coefficient : µ ≈ 0.13
Ave Vertical Force
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Airport Pavement Working GroupApr 24, 2012
Planned Facility Upgrades
• Replace fiber optic data communication line – SPUs to control room.
• Add wireless access point for east end of building.
• Charging station for electric vehicles.• 200,000 lb in-ground scale to facilitate
calibration of test vehicle wheel loads.
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Airport Pavement Working GroupApr 24, 2012
Test Vehicle Projects*
• Study to upgrade vehicle traction drives to incorporate dynamic braking.
• Procure and install hydraulic oil heating system.
• On-going load control system upgrade - Delta controllers and digital servo valves.
* Ryan Rutter to further discuss
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Airport Pavement Working GroupApr 24, 2012
Future NAPTF Schedule
• Continue Traffic CC6.• Finish testing on CC5 HMA sections that were
suspended due to cold weather.• Remove/reinistall HMA overlay on reflective
cracking rig.• Plan and construct CC7 on the low-strength
subgrade. Proposed testing to look at overload on flexible pavements.
• CC7 to also look at perpetual HMA pavements.
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Airport Pavement Working GroupApr 24, 2012
Future NAPTF Schedule (continued)
• Repave the HTP pavement with warm-mix asphalt in conjunction with CC7 HMA construction.
• CC8 concrete pavement test planning beginning. Joint design – load transfer of dowels for thick
slabs on moderate strength subgrades. Joint design – sinusoidal keyways vs. dowels. As-built slab strength vs. predicted slab strength. Slab aspect ratios.
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