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National Airport Pavement Test Facility Update. Airport Pavement Working Group. Don Barbagallo. April 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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National Airport Pavement Test Facility Update Airport Pavement Working Group Don Barbagallo April 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 SUBGRADE CHARACTERIZATION Nuclear Density LWD Profiles CBR Measurement
Preliminary CC 5 Trench Findings CBR Summary
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 • 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 Wheel Encoder Bending, Shear, & Torque Strain Gages
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 Vertical Force Ave Horizontal Force Sliding Friction Coefficient : µ ≈0.13
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/reinistallHMA 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.