DGAC/STAC Infrastructure research

1. DGAC/STACInfrastructure research Current Research Work FAA Airport Pavement Working Group Atlantic City, NJ 24-26 April, 2011

2. Main research topics • French rational design method for airfield pavements • Materials characterization and testing methods : material exchange FAA <-> DGAC/STAC • Dynamic F/HWD data analysis • Towards a rational PCN • Reliability of friction measurements • Water depth modeling on runways

3. French rational design method for airfield pavements A new technical manual • A rational method used in France for highway design for more than 30 years • Development of the airfield rational design method from the highway one. • First restricted to new flexible airfield pavement.

4. French rational design method for airfield pavements • 2 steps : • Mechanical design • Freeze / thaw verification • The mechanical design in 6 steps : 1/ Gathering the data and design parameters (traffic, layers thicknesses, material types and characteristics, risk coefficient…)

5. French rational design method for airfield pavements 2/ Stresses / Strains calculation with an isotropic linear elastic multilayered model • Discretization of the horizontal calculation planes (x,y) located at heights zk using a grid (xi, yj, zk). x : longitudinal axis of the moving load y : transverse direction Calculation planes located at: the HMA base (horizontalextensions) the top of the unbound layers (verticalcontractions)

6. French rational design method for airfield pavements 3/ Individual damage calculation without wandering Deformations induced by the set of moving loads of a landing gear taken into account through the "Miner law continuous integration ": (x) : longitudinal deformation variation

7. French rational design method for airfield pavements 4/ Individual damage calculation with wandering 5/ Cumulated damage calculation 6/ Iterative calculations, setting of the layers’ thickness so that: - dcumulated 1 (and lower than 1), - technological limits regardings materials are satisfied.

8. French rational design method for airfield pavements • The technical manual and its software are achieved • Next steps : • trial period by experts to get a feedback • diffusion to all the users and further applications : overlay design, rigid pavement design, rational ACN/PCN.

9. Materials characterization and testing methods • To compare US and French material properties and behaviour • To compare US and French testing methods used for materials characterization • To compare US and French rational design methods • Analysis of NAPTF data to validate/refine this rational design method. The method has been calibrated using the results of two Airbus full-scale testing programs (flexible PEP and HTPT)

10. Materials characterization and testing methods • Materials exchange FAA <-> DGAC/STAC : French materials received by FAA November 2010: • Asphalt materials from 1995 facility: • 101x69x20 cm block (includes surface and base HMA layers). • Asphalt materials from Bonneuil instrumented facility: • 63x54x21 cm block (includes surface and base HMA layers). • 6 HMA cores of varying depth. • Approximately 150 kg of bagged GNT2 (capping layer) from Bonneuil instrumented facility. • US testing is achieved

11. Materials characterization and testing methods • Materials exchange FAA <-> DGAC/STAC : U.S. material samples received by STAC April 2011: • (2) Econocrete (lean concrete) beams, Item P-306, in steel molds. • (3) Econocrete (lean concrete) cylinders, Item P-306. • (2) Blocks of asphalt base material, Item P-403. • (4) Buckets and (1) bag of crushed aggregate base material, Item P-154 (Crushed quarry screenings). • All materials from NAPTF test items. • French testing has just been completed

12. Materials characterization and testing methods And now, in progress : Comparison and data analysis of the results obtained by FAA and DGAC/STAC

13. French HWD pavement testing methodology (flexible pavements) A new technical guide for: 1) pavement testing 2) data analysis: • Backcalculation • Critical strains calculations • Determination of pavement residual life, and/or bearing capacity (Single Wheel Load, PCN?) Consistent with the new design guidance

14. Dynamic F/HWD data analysis • Technical guide and associated software (PREDIWARE) almost achieved • Next steps: • validation by a user committee • release • Next studies: • overlay design • rigid pavement assessment

15. Towards a rational PCN Study in progress, a new work axis : The aim is to cross the work done on the rational design method and on the HWD data analysis to develop a method to calculate a rational PCN.

16. Reliability of friction measurements • Aims of the study based on the IMAG device • To identify, quantify and reduce uncertainties • To be more confident in friction results • First step : Identification of all the parameters affecting the measurements.

17. Reliability of friction measurements • The main parameters are : Calibration, Tire (wear, pressure), Water depth, Speed, Slip rate, Horizontality of sensors

18. Reliability of friction measurements • The results : • LFC = LFCread 0,10 at 95 km/h • LFC = LFCread 0,09 at 65 km/h • LFC = LFCread 0,08 at 40 km/h • To compare with :

19. Water depth modeling on runways • Modeling of the runway characteristics with the VANI device • Transverse and longitudinal slopes • Evenness • Macro-texture • Friction (micro-texture)

20. Water depth modeling on runways • Modeling of water flow lines based on VANI data • Development of a software to predict the water depth on the runway during a rainy period or a thunderstorm. Input data : • VANI data • rain intensity (weather data) Output data : Water depth Flow model

21. Thank you BROUTIN Michael Michael.broutin@aviation-civile.gouv.fr STAC/IA Infrastructures Aéroportuaires

22. p(t) Structure p(t) G1 G4 G9 G3 G6 G7 G5 G8 Load plate L ur=0 ur=0 H uz=0 Surface AC  Base AC UGA Subgrade French HWD pavement testing methodology (flexible pavements) • Dynamical FE modelling • Use of histories instead of only peak values for backcalculation step