Validated NAPTF Pavement P209/P154 Granular Base/Subbase Rutting Predictions

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Validated NAPTF PavementP209/P154 Granular
Base/Subbase Rutting Predictions

• In Tai Kim Erol Tutumluer
• University of Illinois, Urbana-Champaign

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Introduction

• Rutting of Aggregate Layers
• The only failure mechanism of Unbound Aggregate
  base/subbase layers The Performance
  Indicator!..
• Knowledge is always required of the relative
  contribution of the aggregate layers to the total
  permanent deformation of the airport pavement
  structure
• Current standard laboratory test procedures, such
  as the AASHTO T307-99, not adequate for
  evaluating permanent deformation behavior of
  granular geomaterials because
• Heavier (aircraft) wheel loads applied
• Actual moving wheel load conditions

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FAAs Full Scale Test Facility (NAPTF)

• Low Medium strength flexible sections (5 to 10
  inches Asphalt CBR 4 to 8 subgrade soils)
  failed with up to 4 inches ruts
• Highest contribution to permanent deformations
  often from
• 4 to 30 inches thick P209 base, or
• 12 to 36 inches thick P154 subbase

6-wheel (B777) 4-wheel (B747) Gear Assemblies
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NAPTF Trafficking Results LFC
Wheel Load 45,000-lbs (20.4 metric tonnes) per
wheel After 20,000 passes 65,000-lbs (29.5
metric tonnes) per wheel
(Garg, 2003)
http//www.airporttech.tc.faa.gov
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FAA CEAT Project Objectives

• Characterize Permanent Deformation Behavior
  Laboratory testing of FAAs base and subbase
  materials, P209 and P154
• Develop Prediction Models
• Constant Variable Confining Pressure (CCP
  VCP) Test Conditions
• Investigate Factors Affecting Permanent
  Deformation Accumulation
• Validate Model Performances w/ NAPTF Data

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Laboratory Investigation of Permanent Deformation
Behavior

• P209 Base Material
• Friction Angle (?) 61.7?
• Cohesion ( c) 30 psi

• P154 Subbase Material
• Friction Angle (?) 44?
• Cohesion ( c) 26.4 psi

Material Maximum Dry Density, kN/m3 Optimum Moisture Content,
P209 24.19 (154.9 pcf) 4.7
P154 20.04 (128.3 pcf) 6.5
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FAA NAPTF Permanent Deformation Testing Program
Univ. of Illinois
? Advanced Test Equipment UI-FastCell

• Compression and Extension Stress States
• Constant (CCP) Variable (VCP) Confining Stress
  Paths

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Laboratory Test Program P209 P154
CCP
? Constant Confining Pressure (CCP) Tests -
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Stress Ratios1/s3 4 Stress Ratios1/s3 4 Stress Ratios1/s3 6 Stress Ratios1/s3 6 Stress Ratios1/s3 8 Stress Ratios1/s3 8 Stress Ratios1/s3 10 Stress Ratios1/s3 10
s1d(kPa) s3(kPa) s1d(kPa) s3(kPa) s1d(kPa) s3(kPa) s1d(kPa) s3(kPa)
62.1 20.7 96.6 20.7 144.9 20.7 186.3 20.7
103.5 34.5 172.5 34.5 241.5 34.5 310.5 34.5
165.6 55.2 276.0 55.2 386.4 55.2 ? ?
207.0 69.0 345.0 69.5 ? ? ? ?
Typically 10,000 load applications at each stress
state
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Variable Confining Pressure (VCP) Test Program
Moving wheel load
x
Stresses
sv
Vertical stress
t
sh
Extension
Extension
Horizontal stress
Time
Shear stress
t
Typical pavement element
z
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VCP Test Program
q
s3d 0
CCP
Static failure
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VCP ( s3d s1d )
1
m
p (s1d2s3d)/3 p0 q/3
Compression
q s1d- s3d
p0
Extension
m Dq / Dp slope of stress path
-3
2
CCP Constant Confining Pressure, m
3, s3d 0 (SHRP P46)
s1d 0
- q
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VCP Test Matrix 39 tests
Stress Path Slope (m) 1.5 (compression states) Stress Path Slope (m) 1.5 (compression states) Stress Path Slope (m) 1.5 (compression states) Stress Path Slope (m) 0 Stress Path Slope (m) 0 Stress Path Slope (m) 0 Stress Path Slope (m) -1 (extension states) Stress Path Slope (m) -1 (extension states) Stress Path Slope (m) -1 (extension states)
?3 (kPa) ?1d (kPa) ?3d (kPa) ?3 (kPa) ?1d (kPa) ?3d (kPa) ?3 (kPa) ?1d (kPa) ?3d (kPa)
20.67 72.62 18.12 20.67 65.46 65.46 20.67 15.43 61.73
20.67 120.8 30.18 20.67 108.9 108.9 20.67 25.63 102.7
20.67 168.9 42.24 20.67 152.3 152.3 20.67 35.9 143.6
20.67 217.9 54.43 20.67 196.4 196.4 20.67 46.3 185.1
34.45 120.8 30.18 34.45 108.9 108.9 34.45 25.63 102.7
34.45 201.8 50.43 34.45 181.9 181.9 34.45 42.86 171.5
34.45 282.1 70.48 34.45 254.2 254.2 34.45 59.94 239.7
34.45 362.3 90.6 34.45 326.6 326.6 34.45 76.96 307.9
55.12 193.4 48.37 55.12 174.3 174.3 55.12 41.06 164.3
55.12 322.6 80.61 55.12 290.8 290.8 55.12 68.56 274.2
55.12 451 112.7 55.12 406.5 406.5 55.12 95.84 383.3
68.9 241.6 60.36 68.9 217.7 217.7 68.9 51.33 205.3
68.9 402.9 100.7 68.9 363.1 363.1 68.9 85.57 342.4
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Permanent Deformation (Strain) Models (based on
CCP VCP test data) ? f(s)
s3 Static confining pressure s1d Vertical
dynamic stress s3d Horizontal dynamic
stress N No. of load applications m Stress
path slope A, B, C, D, E regression
parameters
Permanent Strain Models Developed in the form ?p A NB R2 for All Data R2 values Stress Path Slope (m) R2 values Stress Path Slope (m) R2 values Stress Path Slope (m) R2 values Stress Path Slope (m)
Permanent Strain Models Developed in the form ?p A NB R2 for All Data m -1 VCP m 0 VCP m 1.5 VCP m 3 CCP
P209 FAA Base Material P209 FAA Base Material P209 FAA Base Material P209 FAA Base Material P209 FAA Base Material P209 FAA Base Material
CCP ?p A ?1dB ?C ND ( ? 3?3 ?1d ) 0.56 0.24 0.70 0.47 0.86
VCP ?p A ?3B ?1dC ?3dD NE 0.80 0.38 0.78 0.53 -
P154 FAA Subbase Material P154 FAA Subbase Material P154 FAA Subbase Material P154 FAA Subbase Material P154 FAA Subbase Material P154 FAA Subbase Material
CCP ?p A ?1dB ?C ND ( ? 3?3 ?1d ) 0.46 0.62 0.53 0.32 0.85
VCP ?p A ?3B ?1dC ?3dD NE 0.60 0.62 0.53 0.35 -
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ep Model Validation w/ NAPTF Data
NAPTF Load Wander Patterns
Calculate stress states for each wander position
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ep Prediction for NAPTF Load Wander
LFC P154 subbase layer
?p A ?1dB ?C ND
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ep Accumulation for NAPTF Load Sequence 66
passes
Calculate no. of load applications according to
wander distribution
Odd-Numbered Passes Carriage Moves West to
East Even-Numbered Passes Carriage Moves East
to West
Normal Distribution ( s 30.5 in.)
63,64
64,66
61,62
51,52
59,60
57,58
55,56
53,54
43,44
45,46
37,38
47,48
39,40
49,50
41,42
19,20
35,36
21,22
33,34
27,28
31,32
25,26
29,30
23,24
1,2
17,18
3,4
15,16
9,10
13,14
7,8
11,12
5,6
Track No.
-4
-3
-1
-2
1
2
3
4
0
9.843 in
(250 mm) typical
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NAPTF Moving Wheel Stress Paths
FAA National Airport Pavement Test Facility
Compression
LFS section
Extension
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ep Prediction for NAPTF Moving Gear/Wheel Loads
VCP Model dp Prediction
A moving wheel loading consists of five
sequential (1?5) load locations
Stress path slope -1 4 ?1d ?3d
Stress path slope -1 4 ?1d ?3d
Stress path slope 0 ?1d ?3d
Stress path slope 3 ?3d 0
Stress path slope 0 ?1d ?3d
1
2
3
4
5

P154 subbase
6 sublayers Layer 1 Top layer
Pavement elements
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ep Prediction for NAPTF Moving Gear/Wheel Loads
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Other Major Factors Affecting Permanent
Deformation Behavior
Laboratory Testing versus NAPTF Testing
Compacted with vibratory compactor
Unconditioned virgin specimen Loaded with
0.1-sec (equivalent to 50 km/hr) load
duration
Trafficked at 8 km/hr (0.5-sec load duration)
with aircraft gear Previous loading of base
and subbase layers during
pavement construction and slow moving load test
(response test)
Load Pulse Duration and Stress History effects
involved
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Predictions Considering NAPTF Trafficking Speed
Loading Stress History Effects

• A new set of specimens were tested to adequately
  account for NAPTF (1) pulse duration (trafficking
  speed) and (2) stress history effects
• 0.5-second load duration accumulates 40 more
  permanent deformation compared to 0.1-second
  viscoplastic ?
• Slow Moving Response Tests with 36,000-lb wheel
  loads at 0.54 km/h
• 200 load cycles were applied to simulate slow
  moving response test for conditioning specimens
• Stress history ratios used in computing model
  parameter adjustment factors
• (36,000 lbs / 45,000 lbs 0.8)

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Permanent Deformation Predictions Validated with
NAPTF Measured Ruts
S Stress History Effects L Load Duration
Effects
Measured Permanent Deformation
VCP Prediction considering S L
VCP Prediction considering S
CCP Prediction considering S L
CCP Prediction considering S
LFC P154 Subbase
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Summary

• Conducted Laboratory Permanent Deformation
  Testing on the FAAs National Airport Pavement
  Test Facility (NAPTF) P209/P154 Unbound Aggregate
  Base/Subbase Materials
• Power function form stress dependent permanent
  strain (ep) prediction models developed based on
  CCP (stationary repeated loading) VCP (moving
  wheel loading) test data
• Rut accumulations predicted in the NAPTF LFC P154
  subbase layer by properly considering load pulse
  duration (trafficking speed) and previous stress
  history effects
• VCP model predicted much closer to the measured
  NAPTF ruts

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Research Findings/Accomplishments

• A new granular base/subbase permanent deformation
  test procedure was proposed to take into account
  the effects of
• Heavy wheel loads applying stresses up to 90 of
  the shear strength
• Moving wheel loads considering three different
  stress path slopes in VCP testing
• Load pulse duration in accordance with field
  trafficking speed
• Previous stress history preconditioning of
  specimens
• Major Accomplishments
• PhD Dissertation of Dr. In Tai Kim
• August/October 2005
• Final Project Report CEAT Report No. 28

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Current/Future Research Focus

• Investigate the NAPTF trafficking dynamic
  response database to understand complicated
  recovered unrecovered pavement deformation
  behavior due to various combinations of applied
• Load magnitudes and loading sequences
  (application order and stress history effects)
• Trafficking speeds (load duration effects)
• Traffic directions (shear stress reversals)
• Gear spacing or interaction
• Wander positions and wander sequences (order of
  66 loadings)
• Based on the proposed test procedure, fully
  develop a permanent deformation test procedure
  for evaluating airport pavement granular
  base/subbase layer rutting potential
• Study CC3 test section subbase rutting
  performances
• Establish granular layer thickness/performance
  equivalencies

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NAPTF trafficking dynamic response
unrecovered !..
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NAPTF trafficking dynamic response
Base/Subbase Contractive Dilative Behavior
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NAPTF trafficking dynamic response
Load path (stress history) effect
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NAPTF trafficking dynamic response
NAPTF Traffic Direction Effect