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Murphy Flynn Construction Manager FAA National Airport Pavement Test Facility

30 th Annual Airport Conference Hershey, Pennsylvania. March 7, 2007. Murphy Flynn Construction Manager FAA National Airport Pavement Test Facility. Curling Monitoring at NAPTF. First three concrete test items built in 1999 failed prematurely from corner cracks

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Murphy Flynn Construction Manager FAA National Airport Pavement Test Facility

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  1. 30th Annual Airport ConferenceHershey, Pennsylvania March 7, 2007 Murphy Flynn Construction Manager FAA National Airport Pavement Test Facility 1

  2. Curling Monitoring at NAPTF • First three concrete test items built in 1999 failed prematurely from corner cracks • Investigation into slab curling began in 2000 – determine cause of excessive slab curl indoors at NAPTF • Various projects over several years • PCC Mix design • Slab dimensions • Moisture and temperature 2

  3. Twin Slab Project • Two single slabs placed and instrumented in October 2005 • Indoor slab • Outdoor slab Sensors CSG’s 36 Vertical Displacement 18 Thermistors 18 Relative Humidity 6 Embedment 10 Total 88 3

  4. Typical slab center sensors 4

  5. Finished Indoor Slab 5

  6. Finished Outdoor Slab 6

  7. Results from Twin Slab Experiment • Instrumentation showed slabs corners separating from stabilized base • Indoor slab curled approximately 200 mils at peak • Outdoor slab curled approximately 90 mils at peak • Seasonal variations and daily variations observed in both slabs • Multi year monitoring continues 7

  8. Results from Twin Slab • Moisture gradient is the primary factor creating slab curl • Temperature gradient was a minor secondary effect • Developed system for wet curing indoor slabs of test items to prevent early age curling • Developed a system to periodically apply water to indoor concrete test items to control long term curling and reduce corner cracking • Effectively reduced curling to 20 mils or less 8

  9. Curling Monitoring Atlanta Hartsfield-Jackson International Airport 9

  10. Curling Monitoring at Atlanta Hartsfield-Jackson International Airport • Objectives: • to measure slab curling stresses and vertical slab/base separation in the field • compare slab behavior recorded at the NAPTF to behavior of actual airfield slabs • Eventually include slab curling effects in failure models 10

  11. Atlanta Taxiway E Instrumented Pavement Project • Three PCC slabs were instrumented during the reconstruction of RWY 8R-26L and parallel TWY E • Sensors were installed Oct. 16-18, 2006; Concrete was placed Oct. 18, 2006 • Instrumentation had to be more robust than those used at NAPTF 11

  12. Atlanta - Project Location RWY 8L – 26R RWY 8R – 26L ACCESS ROAD TWY E 12

  13. Atlanta Taxiway E –Instrumented Slabs Location 13

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  24. Atlanta Taxiway E Sensor Installation Sept./Oct. 2006 24

  25. Automated Data Acquisition System • Initial data acquired manually. Permanent data acquisition system will be installed late March. • System trialed at FAA Tech Center • Panasonic Tough Book laptop • Cellular modem IO Tech Data Acquisition System Mitsubishi Programmable Logic Controller 25

  26. Remote Power Supply • Power supply trial set up at FAA • Tech Center • 4 – 120 Watt solar panels • 400 Watt wind generator • Power to be mounted near data collection cabinet 26

  27. Concrete Research 27

  28. Innovative Pavement Research Foundation (IPRF) • FAA has partnered with industry to focus on Concrete research for airfields Program established 2001. • Cooperative Agreement with FAA. • P.I.: Gerald Voigt, ACPA • IPRF Program Manager: Jim Lafrenz • FAA Program Manager: David Brill • Research is funded 100% through FAA grants. • Projects are monitored by IPRF Technical Panels. Panel members include FAA and outside experts. • More information: http://www.iprf.org 28

  29. IPRF Projects 04-2 and 06-3:Concrete Overlay Parameters • NAPTF Construction Cycle 4 (CC4). • Project performed at NAPTF by Quality Engineering Solutions (QES) under contract to IPRF. • QES designed & constructed 3 test items on nominal 8 CBR subgrade (300 LF total). QES is responsible for monitoring the tests, does all analysis & prepares the final report. • Under terms of the Cooperative Agreement with IPRF, the FAA prepared the subgrade, performed plate load tests & operated test vehicle per QES plans.. • Final trafficking of CC4 test items took place on 10/3/06. • Plan for 2007-8 is for QES to perform Phase B testing on reconstructed overlays using IPRF FY06 funds. • Funds: • Phase A (04-2): $900K • Phase B (06-3): $900K 29

  30. CC4 Test Item Profiles WEST EAST 30

  31. IPRF Project 02-04:Airfield Pavement Smoothness Criteria • Comparative analysis of "off-the-shelf" pavement smoothness measurement equipment, technology and indices. • Define appropriate smoothness criteria to be used for acceptance, rehabilitation. • Limited to PCC pavements. • Contractor: APR Consultants, Inc. • Funds: $262K • Final report available 2007. 31

  32. IPRF Project 03-01:Design and Construction Guide for in Pavement Lighting • Best Practices document. • Addresses conflicting requirements between civil engineering and electrical engineering details. • Summary of practices that result in satisfactory installations resulting in minimal maintenance requirements. • Contractor: Burns Engineering • Funds: $106K • Final report available 2007 32

  33. IPRF Project 04-01:Develop a New Airfield Concrete Pavement Specification • IPRF will make recommendations to FAA for update to Item P-501, Portland Cement Concrete Pavement. • Address all areas of current spec, including concrete mix design; equipment; concrete placement; opening requirements, etc. • Emphasis on end product requirements. • Contractor: CTL Group • Funds: $411K • Final IPRF report & proposed specification: 2007 33

  34. Alkali-Silica Reactivity (ASR)Research Program • What is ASR? • A chemical reaction that occurs when silica in the aggregate and alkali in the cement react in the presence of water. • The reaction product is a gel that absorbs water and swells, causing cracking. • Potential distresses include cracked and misaligned slabs. There may also be an increased FOD hazard. • ASR is becoming increasingly recognized as a problem at airports. 34

  35. IPRF Project 04-6: Lithium Admixtures and Properties of Early Age Concrete • Project studied properties of plastic and early-age hardened production concrete treated with lithium nitrate (LiNO3) as an admixture. • Combined field testing with laboratory investigations. • Looked at concrete properties including: Air content and unit weight, workability, strength (compressive and flexural), shrinkage, maturity. • Conclusions: • No significant effects on early-age properties at the recommended dosage. • Some statistically significant effects (e.g., reduction in 28-day compressive strength) found at 2 – 4 times recommended dosage. • Based on results, keep 100% dosage as recommended maximum. 35

  36. IPRF Project 03-10:Topical Application of Lithium • 5-year field study, $630,000. • Contractor is Vector Corrosion Technologies. • 3 U.S. Airports studied: • Cheyenne, Wyoming • Phoenix, Arizona • Atlanta, Georgia • Investigating use of topical lithium treatment to mitigate/retard ASR damage. Test Area at Cheyenne Regional Airport (TWY B) Lithium Application at Cheyenne Airport 36

  37. IPRF Projects 03-9 and 04-8:ASR and De-Icing Chemicals • Alkali-bearing chemicals are commonly used as anti-icing and ice melting agents at airports: • Potassium acetate (KAc) and sodium acetate (NaAc) • Sodium formate (Used in Europe but not common on the U.S.) • U.S. airports observed that deicers seemed to contribute to a rapid increase in ASR activity. • FAA sponsored an IPRF project to • determine the severity of this phenomenon. • evaluate procedures for mitigation. • Interim test procedure • Modified ASTM 1260 (mortar bar) test. 37

  38. Guidance on Mitigating ASR • FAA Guidance(http://www.faa.gov/airports_airtraffic/airports/construction/): • Advisory Circular 150/5380-8, Handbook for Identification of Alkali-Silica Reactivity in Airfield Pavements • Engineering Brief No. 70, Accelerated Alkali-Silica Reactivity in Portland cement concrete pavements exposed to runway deicing chemicals. Interim recommendations from IPRF deicer study. • IPRF Reports (www.iprf.org): • Test Method to Assess Potential Reactivity of Aggregates in Presence of Airfield Deicing Chemicals (Mortar Bar Test) • Lithium Admixtures (LiNO3) And Properties of Early Age Concrete. 38

  39. Hot Mix Asphalt Research 39

  40. Bridging the Gap • FAA study underway to bring Superpave methodology into large commercial airport HMA • Goal: Develop a specification that will produce equivalent or better HMA than current P-401 Marshall mixes • Marshall mixes have been performing well • Currently use PG binders • FAA P-401 gradations match closely to Superpave requirements 40

  41. Current FAA HMA Specifications • ENGINEERING BRIEF NO. 59A “ITEM P‑401 PLANT MIX BITUMINOUS PAVEMENTS (SUPERPAVE)” • Purpose : provide guidance on using asphaltic concrete mixtures designed with Superpave (gyratory) techniques. • Available online at: http://www.faa.gov/airports_airtraffic/airports/ construction/engineering_briefs/ 41

  42. Engineering Brief 59A • Currently allows the use of Superpave mixes on airports with gross aircraft weights of 100,000 lbs. or less • Requires mix to be developed using 100 gyrations for Ndes • Use PG binder recommended by local Department of Transportation 42

  43. FAA Study Phase I • Phase I: Study will produce a matrix of mixes using both Marshall mix design and Superpave mix design • Matrix will encompass: • Various aggregate geologies • Limestone • Basalt • Granite • Etc. 43

  44. FAA Study Phase I • Matrix will encompass: • Various asphalt binders • PG 64-22 • PG 70-22 • PG 76-22 (Polymer Modified Binders) 44

  45. FAA Study Phase I • Compare volumetrics of mixes • Measure volumetrics at 75 blow Marshall hammer (current FAA spec.) • Measure volumetrics at various compaction levels using Superpave gyratory compactor • Ndes gyrations 65, 75 and 100 • Identify appropriate Ndes level to match volumetrics of P-401 Marshall mixes 45

  46. FAA Study Phase I • Collect history and performance of existing projects • Identify airfields paved using EB 59 standards • EB 59 requires projects using Superpave to collect Marshall Stability and air voids of the Job Mix Formula. • Evaluate performance of pavement compared to design life. 46

  47. FAA Study Phase II • Performance Testing • Produce a select number Marshall mixes and Surperpave mixes • Superpave mixes will be produced at Ndes developed in Phase I volumetric testing • Proposed Performance tests • Repeated Shear at Constant Height using Superpave Shear Tester • (AASHTO T320 Method C) 47

  48. FAA Study Phase II • Proposed Performance tests • Rutting Susceptibility Using the Asphalt Pavement Analyzer • (AASHTO TP63) • Simple Performance Test, Repeated Load Testing in Uniaxial Compression • (NCHRP Report 465, appendix B) • Dynamic Modulus Test (E*) • (AASHTO TP62) 48

  49. AAPTP • The AAPTP was established in 2004 through a cooperative agreement between the Federal Aviation Administration and Auburn University • Funded through FAA grants • Projects are monitored by AAPTP Technical Panels. Panel members include FAA and outside experts. • More at http://www.aaptp.us/ 49

  50. AAPTP Superpave Projects • Project 04-03, Implementation of Superpave Mix Design for Airfield Pavements - $470,000: • Goal is to produce fully documented guidance on the procedures and processes needed to incorporate Superpave technologies into FAA standard airfield mix design practice. 50

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