Presented to: By: Date: Federal Aviation Administration National Airport Pavement Test Facility Update Airport Pavement Working Group Don Barbagallo April

Presented to:

By:

Date:

Federal AviationAdministration

National Airport Pavement Test Facility Update

Airport Pavement Working Group

Don Barbagallo

April 24, 2012

2Federal AviationAdministration

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



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.



Post Traffic Testing

• CC5 examines the effect of multiple gear configurations on low strength subgrade flexible pavement life.



CC5 TRENCH AREA



CC5 TRENCH SUBGRADE CHARACTERIZATION

Nuclear Density LWD

CBR Measurement Profiles



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

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CBR

Average CBRin Dupont Clay Post Traffic Subgrade

Series1

Pre-

Traffi

c CBR



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



CC6 Rigid Pavement Tests

• Dr. David Brill & Mr. Josh Davis will present update on CC6 testing.



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.



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



Reflective Cracking Test Rig



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.



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.



Single Wheel Module Instrumentation

Bending, Shear, & Torque Strain Gages Wheel Encoder



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.



Aircraft Tire Friction Braking Testing

• Measure forces and friction coefficient for snow covered surface.

• Single wheel module with locked wheel



Aircraft Tire Friction Strain Gage

Ave Horizontal Force

Sliding Friction Coefficient : µ ≈ 0.13

Ave Vertical Force



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.



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



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.



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.

Documents

Presented to: By: Date: Federal Aviation Administration National Airport Pavement Test Facility Update Airport Pavement Working Group Don Barbagallo April