Presentation on theme: "1 Murphy Flynn Construction Manager FAA National Airport Pavement Test Facility 30 th Annual Airport Conference Hershey, Pennsylvania March 7, 2007."— Presentation transcript:
1 Murphy Flynn Construction Manager FAA National Airport Pavement Test Facility 30 th Annual Airport Conference Hershey, Pennsylvania March 7, 2007
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
3 Twin Slab Project Sensors CSG’s36 Vertical Displacement18 Thermistors18 Relative Humidity6 Embedment10 Total88 Two single slabs placed and instrumented in October 2005 Indoor slab Outdoor slab
4 Typical slab center sensors
5 Finished Indoor Slab
6 Finished Outdoor Slab
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
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
9 Curling Monitoring Atlanta Hartsfield-Jackson International Airport
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
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 , 2006; Concrete was placed Oct. 18, 2006 Instrumentation had to be more robust than those used at NAPTF
12 Atlanta - Project Location ACCESS ROAD RWY 8R – 26L TWY E RWY 8L – 26R
13 Atlanta Taxiway E – Instrumented Slabs Location
24 Atlanta Taxiway E Sensor Installation Sept./Oct. 2006
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
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
27 Concrete Research
28 Innovative Pavement Research Foundation (IPRF) FAA has partnered with industry to focus on Concrete research for airfields Program established 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:
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 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
30 CC4 Test Item Profiles WEST EAST
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.
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
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
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.
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 (LiNO 3 ) 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.
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. Lithium Application at Cheyenne Airport Test Area at Cheyenne Regional Airport (TWY B)
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.
38 Guidance on Mitigating ASR FAA Guidance (http://www.faa.gov/airports_airtraffic/airports/construction/) :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) :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.
39 Hot Mix Asphalt Research
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
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: construction/engineering_briefs/
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 N des Use PG binder recommended by local Department of Transportation
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.
44 FAA Study Phase I Matrix will encompass: Various asphalt binders PG PG PG (Polymer Modified Binders)
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 N des gyrations 65, 75 and 100 Identify appropriate N des level to match volumetrics of P-401 Marshall mixes
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.
47 FAA Study Phase II Performance Testing Produce a select number Marshall mixes and Surperpave mixes Superpave mixes will be produced at N des developed in Phase I volumetric testing Proposed Performance tests Repeated Shear at Constant Height using Superpave Shear Tester (AASHTO T320 Method C)
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)
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
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.
51 AAPTP Projects Project 04-02, PG Binder Grade Selection for Airfield Pavements - $150,000 Develop procedures and guidance on selecting PG Binders for airfield pavements – including grade bumping Will address procedures and recommendations for binder selection Grade bumping for heavier loaded pavements which may include PMA’s Report expected 2007
52 Stone Matrix Asphalt - SMA Gap Graded Stone on Stone contact hot mix asphalt Combines strong coarse aggregate with a high asphalt content of 6-8% Contains cellulose or mineral fibers to prevent drain down of binder Developed in Europe years ago Used by approximately 30 of the 50 United States
53 Stone Matrix Asphalt - SMA SMA costs 20-40% more than conventional HMA mixes Predicted service life is % greater than conventional HMA and 20-30% greater than Superpave Presently no FAA specification regarding the use of SMA on airfields.
54 FAA Plans for SMA Study Collect field performance data on non P-401 specification asphalt mixes under heavy loads Proposed Full scale testing of various types of HMA – may include: Stone Matrix Asphalt – SMA Permeable Friction Courses Open Graded Friction Courses Specialized Thin Lift HMA mixes
55 FAA Plans for SMA Spring Inspection of Chinese Airports using SMA overlays and reflective cracking prevention measures Coordinated survey with Civil Aviation Authority of China (CAAC) and China Airport Construction Corporation (CACC) Airports Include Harbin Airport (cold climate) Capital Airport, Beijing (moderate climate) Gaoqi International Airport (warm climate)
56 AAPTP – SMA Project Project Evaluation of Stone Matrix Asphalt (SMA) for Airfield Pavements Evaluate and document the extent of use and performance of SMA pavements on airfields in the US, Europe and elsewhere Provide guidance to the FAA on benefits and limitations of SMA use on airfields and the requirements / specifications needed to implement SMA
57 Recycled Material in Asphalt FAA Specification P-401 allows for the use of RAP in pavement mixtures: Paragraph P “The RAP shall be of a consistent gradation and asphalt content and properties.” “RAP should only be used for shoulder surface course mixes and for any intermediate courses. The amount of RAP shall be limited to [ ] percent.” “The amount of RAP shall be limited to 30 percent, as long as the resulting recycled mix meets all requirements that are specified for virgin mixtures.”
58 Recycled Material in Asphalt Most Engineers are resistant to specifying or allowing RAP in Airport pavements Concerns of consistent quality of material Age of the RAP – asphalt maybe brittle from age hardening Other impurities or contaminants
59 AAPTP – Reclaimed Asphalt Project Use of Reclaimed Asphalt Pavements (RAP) in Airfields HMA Pavements Provide a comprehensive document that identifies the benefits, successful use, and criteria for use on airfields to encourage further consideration and wider use of RAP on airfield pavements.
60 AAPTP – RAP Project will include a literature review of current state of the practice Field performance review Development of guidelines / recommendations Mix designs with RAP Quality control requirements Costs savings and life cycle costs
61 Summary FAA and industry are working together Goal is to keep pace with advances in HMA and PCC technologies Extend the life cycle of existing and new pavements Reduce costs to the FAA and the flying public