Full-Scale Testing Overload Update Presented to: REDAC Subcommittee on

Full-Scale Testing Overload Update Presented to: REDAC Subcommittee on Airports By: David R. Brill, P.E., Ph.D. Date: March 15, 2016 Federal Aviation Administration

Review - Current ICAO Overload Criteria ICAO Annex 14, “Aerodrome Design and Operations,” defines the following overload criteria: – for flexible pavements, occasional movements by aircraft with ACN not exceeding 10 per cent above the reported PCN should not adversely affect the pavement; – for rigid or composite pavements, in which a rigid pavement layer provides a primary element of the structure, occasional movements by aircraft with ACN not exceeding 5 per cent above the reported PCN should not adversely affect the pavement; – the annual number of overload movements should not exceed approximately 5 per cent of the total annual aircraft movements. In addition, overloads should not be allowed on pavements exhibiting distress or failure, or during periods of thaw. The airport authority should review the pavement condition regularly, and review overload criteria periodically. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 2

CC8 Overload Test Objectives: – Evaluate the current ICAO overload criterion (5% above PCN) for rigid pavements. – Develop new rational overload criteria. – Bring CC8 test pavement to a suitable condition to receive PCC overlay in next phase (target SCI 80). Traffic testing began February 22 and continued through March 3 (2 weeks). Traffic will resume in the spring (exact date TBD). March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 3

CC8 Test Area Layout NORTH Test Item (no overload) SOUTH Test Item (5%-25% overload based on PCN) March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 4

CC8 Test Section Concrete Flex Strength R 650 psi (tested reserved beams at approx. 180 days) 9 in. PCC surface / P-154 base layer (representative of non-hub/GA facility). FAARFIELD 1.4: – Use NAPTF dual gear @ 20,000 lbs./wheel. – FAARFIELD life prediction 10,405 passes. COMFAA 3.0: – PCN 21/R/C (both test items) – ACN of dual gear 20.4/R/C Subgrade k 120 pci (average of preconstruction plate load tests) March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 5

Overload Traffic Plan (Initial) 1. Normal Load (North & South). Run one complete wander pattern (66 passes) on both test items using dual gear @ 20,000 lbs./wheel (ACN 20.4). 2. Overload (South test item only) using 2D gear: Overload (nominal) 5% 10% 15% 20% 25% Overload (actual) 4.0% 10.1% 13.2% 19.6% 26.0% ACN 21.8 23.1 23.8 25.1 26.5 2D Wheel Load, lbs. 21,500 22,500 23,000 24,000 25,000 3. Resume normal load (North & South). Continue traffic using dual gear @ 20,000 lbs./wheel until failure is observed (defined as 50% of slabs with 1 through crack). March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 6

Initial Trafficking (Feb. 22-24) Trafficking on Feb. 24, 2016 Day Normal Wanders Overload Wanders 2/22/2016 1 5 (5%, 10%, 15%, 20%, 25%) 2/23/2016 9 - 2/24/2016 10 - Initial trafficking (20 wanders 1320 passes) caused no visible damage on either test item. Decided to re-evaluate PCN and increase loads. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 7

Strain Gage Data Analysis Average peak tensile strain from all longitudinal bottom gages 59 μ-strain. Corresponds to max. 319 psi at bottom surface of 9" PCC slabs. 59 μ-strain Stress is less than 50% of flexural strength (650 psi) and less than assumed in the original analysis. Based on the structural capacity obtained from strain gages, increase PCN and revise the test plan. New PCN 30/R/C for both test items. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 8

Revised Traffic Plan 1. Normal Load (North & South). Run one complete wander pattern (66 passes) on both test items using dual gear @ 28,000 lbs./wheel (ACN 29.9). 2. Overload (South test item only) using 2D gear: Overload (nominal) 5% 10% 15% 20% 25% Overload (actual) 4.7% 9.3% 14.3% 19.3% 24.3% ACN 31.4 32.8 34.3 35.8 37.3 2D Wheel Load, lbs. 28,500 29,500 30,500 31,500 32,500 3. Resume normal load (North & South). Continue traffic using dual gear @ 28,000 lbs./wheel until failure is observed (defined as 50% of slabs with 1 through crack). March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 9

Revised Traffic (Feb. 25 – Mar. 3) Day Normal Wanders Overload Wanders 2/25/2016 1 3 (5%, 10%, 15%) 2/26/2016 8 2 (20%, 25%) 2/29/2016 10 - This slide will be updated based on testing results week of Feb. 29. First 3 overload wanders caused no visible cracks or damage. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 10

CC7 Overload Update Objectives: – Evaluate the current ICAO overload criterion (10% above PCN) for flexible pavements. – Develop new rational overload criteria. – Consider ACN, percent used pavement life (CDF), overload gear type (D, 2D, 3D). Current status: – 12,606 passes have been completed. – Overloads at ACNs 50% & 75% above PCN and at 1.0 CDF remain to be tested. Planned for spring. – Traffic is on hold while we complete testing on CC7 North. (Colder temperatures are preferred for North test objectives.) March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 11

Preliminary Observations (review from the last meeting) Observed an increase in the rate of rutting after overload of 0.5 CDF and 130% of PCN. Number of wheels in overload gear does not appear to have a significant effect on permanent damage for the same ACN or CDF. MDDs show rutting accumulates primarily in the P-154 subbase layer. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 12

CC7 Test Item Layout March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 13

CC7 Overload Test Items 40-ft. (12.2-m) test items separated by 10-ft. (3 m) transitions. CBR 5 (subgrade category C) All 6 test items have the same structure. Thin HMA sections represent GA airports receiving occasional overload operations. – – 3 in. P-401 6 in. P-209 3 in. P-401 6 in. P-209 20 in. P-154 P-154 thickness designed to give nominal PCN 35/F/C. – – Assumed “lifetime” traffic of 27,000 passes of NAPTF 72,000-lb. dual gear (36,000 lbs. per wheel). Use COMFAA 3.0 to compute PCN. Subgrade CBR 5 March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 14

Instrumentation Layout (LFC1-S) TEST ITEM LFC1-S TRANSITION T-1S 1A / 1A /E D TSG – Transverse Strain Gage MDD – Multi-Depth Deflectometer o March 15, 2016 PC – Pressure Cell Center of Wander Pattern MS – Moisture Sensor SS – Suction Sensor 6A /D T – Thermocouple T- SS -2 A/ D M S2A /E TS TS TS G - G- G 15 14 13 LS G LS -13 G LS -14 G15 M PCDD 7 -7 A/ F M S- SS - LSG – Longitudinal Strain Gage 10 ft. Full-Scale Testing - Overload Update Federal Aviation Administration 15

General Test Procedures ACN-Based Overload Test Items: 1. 2. 3. 4. 5. Traffic at “normal” load (D-36) until rate of rut depth accumulation (RRDA) stabilizes*. Increase load to 110% PCN. Traffic until RRDA stabilizes, but not more than 1350 passes (5% lifetime traffic). Resume traffic at normal load. Observe any change in RRDA or other responses (MDD, strain). Increase load to 120% PCN and traffic until RRDA stabilizes. Repeat steps 3 & 4 following the overload schedule. Continue until failure is observed. * “Stable” is defined as an approximately constant rate of total rut depth accumulation with applied passes, following any initial shakedown phase. March 15, 2016 CDF-Based Overload Test Items: 1. Traffic at “normal” load (D-36) until rate of rut depth accumulation (RRDA) stabilizes*. 2. Apply one wander pattern at overload designed to consume CDF 0.1. 3. Resume traffic at normal load. Observe any change in RRDA or other responses (MDD, strain). 4. Apply one wander pattern at overload designed to consume CDF 0.25. 5. Resume traffic at normal load. Observe any change in RRDA or other responses (MDD, strain). 6. Apply one wander pattern at overload designed to consume CDF 0.5. 7. Resume traffic at normal load. Observe any change in RRDA or other responses (MDD, strain). 8. Apply one wander pattern at overload designed to consume CDF 1.0. 9. If Step 6 does not fail the test item, return to normal load(dual) and traffic until the pavement behavior stabilizes or failure is observed. 10. Repeat Steps 8 and 9 until failure. Full-Scale Testing - Overload Update Federal Aviation Administration 16

Overload Schedules Indicates that overload has been completed. ACN-Based Overload Test Items LFC S-1, 2, 3 (a) ACN Criterion Gear Overload Type D 100% PCN 110% PCN D 119% PCN D 126% PCN D D 146% PCN D 164% PCN 110% PCN 2D 121% PCN 2D 130% PCN 2D 2D 149% PCN 2D 175% PCN 111% PCN 3D 120% PCN 3D 130% PCN 3D 3D 148% PCN 3D 171% PCN ACN Passes 35.02 38.38 41.82 44.14 51.26 57.56 38.63 42.44 45.65 52.31 61.30 38.71 42.06 45.56 51.91 59.76 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A OVERLOAD REPEATED March 15, 2016 Wheel Load, lbs.1 36,000 39,000 42,000 44,000 50,000 55,000 35,500 38,000 40,000 44,000 49,000 34,500 36,500 38,500 42,000 46,000 CDF-Based Overload Test Items LFC S-3, 4, 5 (a) CDF Criterion Gear Overload Type CDF 0.09 D CDF 0.25 D CDF 0.49 D D CDF 0.98 CDF 0.10 2D CDF 0.25 2D CDF 0.51 2D 2D CDF 0.98 CDF 0.10 3D CDF 0.25 3D CDF 0.51 3D 3D CDF 1.06 ACN Passes N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) 66 (1 wander) Wheel Load, lbs.2 46,000 52,000 57,000 62,500 40,500 45,500 50,000 54,500 37,000 41,500 45,500 50,000 Based on COMFAA 3.0 1 Based on FAARFIELD 1.4 2 Wheel loads are adjusted to the nearest 500 lbs. due to vehicle limitations. Full-Scale Testing - Overload Update Federal Aviation Administration 17

CC7 Overload Test Summary As of March 15, 2016 Test Phase Dates 1 2 10/6/14 – 10/16/14 3 4 5 10/20/14 10/21/14 – 10/28/14 10/29/14 – 11/13/14 11/17/14 11/17/14 – 11/25/14 12/2/14 – 12/4/14 Vehicle Passes Test Items LFC1-S – LFC3-S Wanders Passes Test Items LFC4-S – LFC6-S Passes Description 1-924 924-990 991-1650 1-14 15 16-25 1-924 925-1584 1-924 925-990 - Initial normal load 0.1 CDF Overload 10% ACN Overload 1650-3168 3169-3234 3235-4224 4225-4752 26-48 49 50-64 65-72 1585-3102 3103-4092 4092-4620 991-2508 2509-2574 2574-3102 4753-5544 5545-5610 5611-6468 6468-8778 73-84 85 86-98 99-133 4621-5412 5413-6270 6271-8580 3103-3894 3895-3960 3961-6270 Resume Normal Load 0.25 CDF Overload 20% ACN Overload Resume Normal Load Test suspended until June 2015 Resume Normal Load 0.50 CDF Overload 30% ACN Overload Resume Normal Load 8779-8844 8845-10362 10363-12606 134 135-157 158-191 8581-10098 10099-12342 6271-6336 6337-8580 12606 191 12342 8580 12/4/14 6 7 8 9 10 6/15/15 – 6/22/15 6/29/15 6/29/15 – 7/6/15 7/8/15 – 8/10/15 8/31/15 8/31/15 – 9/10/15 9/14/15 – 10/19/15 10/19/15 Total March 15, 2016 Full-Scale Testing - Overload Update Repeat 0.50 CDF O/L Repeat 30% ACN O/L Resume Normal Load Test suspended to traffic CC7 North Federal Aviation Administration 18

Rut Depth Monitoring Physical 16-foot straight edge. Rail-to-rail profile data. – Generates raw data files at 2.5 mm from Selcom laser. – Decimate to 25 mm. – Compute a virtual 16-ft. straight edge rut depth. 360 Ultra-High-Speed Laser Scanner (Leica Model P20) – New source of highly accurate profile data. – Use scans to correct rail-to-rail profiles for beam curvature. – Extracting transverse profiles from acquired scans is a time consuming process. We are working to improve efficiency. Profile data are collected: – After every completed wander pattern (66 passes). – At intermediate passes on the zero track (24 and 48 passes) during overload or if deemed necessary. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 19

Rut Depth Monitoring Rail-to-Rail Profiler New Transverse Profile Monitoring Software Automatically corrects profile based on fixed reference. Computes maximum rut depth for “virtual” 16-foot straight edge (or any length). Gives accumulated rut depth and upheaval at each section. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 20

Transverse Profile Analysis CC7 South Transverse Profiles Sta. 2 75 1 UPHEAVAL CORRECTED BASELINE 0.5 Pass No. 0 924 0 0 5 10 15 20 25 30 35 1056 2508 RUT Relative Elevation, inch -0.5 2532 3894 3918 -1 6270 6294 -1.5 8580 -2 -2.5 -3 -3.5 -4 March 15, 2016 -Green is the last profile before applying the overload. -Purple is the first profile after applying the overload. Offset from South Edge of Pavement, ft Full-Scale Testing - Overload Update Federal Aviation Administration 21

Rut Depth/Upheaval – LFC-1 2-Wheel Gear Overload CC7 South Station 10 1 0 0 2000 4000 6000 -2.5 10000 12000 14000 30% ACN OVERLOAD (REPEAT) 30% ACN OVERLOAD -1.5 20% ACN OVERLOAD -1 -2 Pass Number Rut March 15, 2016 8000 -0.5 10% ACN OVERLOAD Relative Elevation, inch 0.5 Upheaval Full-Scale Testing - Overload Update Federal Aviation Administration 22

Rut Depth/Upheaval – LFC-2 4-Wheel Gear Overload CC7 South Station 75 1 0.5 0 2000 4000 6000 10000 12000 14000 30% ACN OVERLOAD (REPEAT) -2.5 -3 30% ACN OVERLOAD -1.5 20% ACN OVERLOAD -1 -2 Pass Number Rut March 15, 2016 8000 -0.5 10% ACN OVERLOAD Relative Elevation, in. 0 Upheaval Full-Scale Testing - Overload Update Federal Aviation Administration 23

Rut Depth/Upheaval – LFC-3 6-Wheel Gear Overload CC7 South Station 125 1 0.5 -0.5 0 2000 4000 6000 -3.5 10000 12000 14000 30% ACN OVERLOAD (REPEAT) -3 30% ACN OVERLOAD -2 20% ACN OVERLOAD -1.5 -2.5 Pass Number Rut March 15, 2016 8000 -1 10% ACN OVERLOAD Relative Elevation, in. 0 Upheaval Full-Scale Testing - Overload Update Federal Aviation Administration 24

Rut Depth/Upheaval – LFC-4 6-Wheel Gear Overload CC7 South Station 175 (LFC4-S) 1 0.5 Relative Elevation, in. 0 -0.5 0 2000 4000 6000 8000 10000 -1 Test Interrupted -1.5 -2 -2.5 -3 -3.5 -4 0.1 CDF 0.25 CDF 0.5 CDF (Repeat) Pass Number RD March 15, 2016 0.5 CDF Upheaval Overload Applied Full-Scale Testing - Overload Update Federal Aviation Administration 25

Rut Depth/Upheaval – LFC-5 4-Wheel Gear Overload CC7 South Station 225 1 0.5 Relative Elevation, in. 0 -0.5 0 2000 4000 6000 8000 10000 -1 Test Interrupted -1.5 -2 -2.5 -3 -3.5 -4 0.1 CDF 0.25 CDF 0.5 CDF Pass Number Overload Applied March 15, 2016 0.5 CDF (Repeat) RD Full-Scale Testing - Overload Update Upheaval Federal Aviation Administration 26

Rut Depth/Upheaval – LFC-6 2-Wheel Gear Overload CC7 South Station 275 1 0.5 Relative Elevation, in. 0 -0.5 0 2000 4000 6000 8000 10000 -1 Test Interrupted -1.5 -2 -2.5 -3 -3.5 -4 0.1 CDF 0.25 CDF 0.5 CDF Pass Number Overload Applied March 15, 2016 0.5 CDF (Repeat) RD Full-Scale Testing - Overload Update Upheaval Federal Aviation Administration 27

Summary – CC7 Overload Sections were designed for 27,000 passes at the normal load. Over 12,000 passes applied, including overloads. – No early structural failure observed yet. – Max. upheaval outside the trafficked area 0.5 in. (up to 0.75 in. at sta. 1 25). – Deep ruts observed mainly in the P-154 subbase. Testing will resume with additional high overloads ( 50% and 75% PCN, and 1.0 CDF) that may cause obvious structural failure. March 15, 2016 Full-Scale Testing - Overload Update Federal Aviation Administration 28