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State-of-Practice on the Use of
Geosynthetics in Roadway
Applications
Mark H. Wayne, Ph.D., P.E.
Tensar International
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30+ YEARS
Foundation & Pavement
Optimization
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FEDERAL HIGHWAY ADMINISTRATION
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Why Geogrids?
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• Construction Platform
• Paved Road
Flexible Pavement Design
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BEFORE Subgrade Stabilization Geogrid
Traffic Course Geogrid
12” PennDOT 2A Mod.
12” PennDOT 2A Mod.
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AFTER
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SEPARATION
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Interface Immobilization
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A Sieve Analysis of Tennis Balls… Particle Size Distribution
0
20
40
60
80
100
0.0010.010.1110100
Grain Size (mm)
% F
iner b
y W
eig
ht
65 mm Uniform Diameter
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… and also Marbles
Particle Size Distribution
0
20
40
60
80
100
0.0010.010.1110100
Grain Size (mm)
% F
iner b
y W
eig
ht
13 mm Uniform Diameter
5x
65 mm
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Subgrade Particles Cannot Infiltrate Aggregate
Fill Just as Marbles Cannot Infiltrate Tennis
Balls, Provided They Don’t Move.
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Filter Criteria
• For Clayey Subgrades:
• For Silty Subgrades:
5 D
DRatio Piping
s
f
85
15
5 D
DRatio Piping
s
f
85
15
25 D
DRatio Size Average
s
f
50
50
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So if Water is Present and Filter
Criteria are Not Satisfied…
• (1) Consider an Alternative (i.e. Sandier) Aggregate Fill, at Least for the First Lift.
• (2) Consider a Nonwoven Geotextile Beneath the Geogrid, but Only if the Subgrade is Not Silty.
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AGGREGATE INTERACTION
FHWA Aperture Size Criteria
Aperture size > D50 of Aggregate Fill
and < 2D85 of Aggregate Fill
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UNPAVED ROAD DESIGN
Full Scale Testing Required to Calibrate and Validate
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• FHWA Separation Criteria (Piping Ratio) ▫ D15 fill = 0.15mm
▫ D85 subgrade = 0.35mm
▫ D15/D85 = 0.43<5 OK
• Average Size Ratio ▫ D50fill = 3mm
▫ D50subgrade=0.1mm
▫ D50fill/D50subgrade=30 not < 25 but close and still worked fine for
the SM used in this study.
• FHWA Aperture Size Criteria (Interaction) ▫ Aperture size > D50 of GAB (3mm) and < 2D85 of GAB
▫ TX130S – 22 mm >3 mm OK and < 2*18 or 36mm OK
▫ BX1100 – 25mm/33mm > 3mm OK and < 2*18 or 36mm OK
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PAVED ROAD DESIGN
AASHTO ‘93
MEPDG
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AASHTO STANDARD PRACTICE
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Roadbed Adjustment Reliability Adjustment
On site performance equation
AASHTO 93
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PAVED ROAD DESIGN
Converted to a layer depth using coefficients. SN = a1D1 + a2D2m2 + a3D3m3 + …
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PAVED ROAD DESIGN
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MEPDG Output*
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
0 2 4 6 8 10 12 14 16
AC Thickness (in)
All
iga
tor C
ra
ck
ing
%
SG Mr = 30 ksiSG Mr = 30 ksiSG Mr = 25 ksiSG Mr = 25 ksi
SG Mr = 20 ksiSG Mr = 20 ksi
SG Mr = 15 ksiSG Mr = 15 ksi
SG Mr = 8,000SG Mr = 8,000
SG Mr = 3,000SG Mr = 3,000
*Courtesy Applied Research Associates, Inc.
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Service Life*
*Courtesy Applied Research Associates, Inc.
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Performance vs. Index Property
0
2
4
6
8
10
12
14
16
18
0 5 10 15 20 25 30 35
Tra
ffic
Be
ne
fit
Ra
tio
(T
BR
)
Tensile strength at 5% strain (kN/m)
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• Full-Scale Testing
Performance Evaluation
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• Full-Scale Testing
Performance Evaluation
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Biaxial Geogrid Performance
0
2
4
6
0
2
4
6
0.000 0.001 0.002 0.003 0.004
TBRSN
Subgrade Vertical Strain
SN TBR
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Geogrid Performance
2
7
6 8 10 12 14 16 18
TIF
Base Course Thickness (in.)
4-in. AC 6-in. AC 8-in. AC
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• Use of Performance Based Testing
Flexible Pavement Design
SN = a1D1 + a2D2m2 + a3D3m3 + …
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Flexible Pavement Design
MSL Aggregate thickness (in.)
Subgrade Resilient Modulus, Mr (psi)
5,000 7,500 10,000
6 0.273 0.270 0.266
8 0.247 0.243 0.240
10 0.231 0.228 0.224
12 0.216 0.213 0.210
14 0.205 0.203 0.200
16 0.197 0.195 0.193
18 0.191 0.189 0.187
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• Optimize Pavement Foundation
▫ Design Stabilization Platform
▫ This is a Stabilization Layer
• Optimize Pavement
▫ Design Base Course Stabilization Layer
▫ Full Scale Testing for Support
Summary
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• Laboratory Performance Testing
▫ T307 Resilient Modulus
• Construction QC/QA
▫ Intelligent Compaction
▫ Dynamic/Static Plate Load Testing
Future Practice
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T307 Triaxial Cell
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T307 Resilient Modulus
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
0 10 20 30 40 50 60 70 80 90
Bulk Stress (psi)
Resil
ien
t M
od
ulu
s,
Mr
(psi)
CONTROL
TX5
Power
(CONTROL)Power (TX5)
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T307 Quick Shear
0
20
40
60
80
100
120
140
160
0 1 2 3 4 5 6
Axial Strain, %
Axia
l S
tress, p
si
Control
TX5
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IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering ks indicates changes in support conditions due to
changes in pavement foundation materials.
Soft
Stiff
Medium
Silty Clay Sand Crushed
Limestone
Courtesy Iowa State University
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IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering
Dis
tan
ce
(m
)
0
20
40
60
80
100
120
140
160
180
Pass 1 2 3 4 5 6 7 8
Lane12345
Localized
Wet Area
Cohesive
Subgrade
ks shows compaction progress and soft area.
Courtesy Iowa State University
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IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering
RICM and PLT Seminar – David J. White 45 11/6/2012
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IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering
Courtesy GeoMatters
Automated in situ measurement technologies are
setting new standards for quality assessment.
This equipment is US Patent Pending disclosed in U.S. Provisional Patent Application No. 61/621,059, filed April 11,
2012. A South American application will claim priority back to the pending U.S. provisional patent application.
Automated testing to assess:
• Modulus of subgrade reaction
• In situ resilient modulus
• Confining stress dependent
cyclic modulus
APLT
Number of Load Cycles
0 200 400 600 800 1000
In S
itu
Re
silie
nt
Mo
du
lus
(p
si)
0
2000
4000
6000
8000
10000
12000
Pe
rma
ne
nt
De
form
ati
on
(in
ch
es
)
0.0
0.2
0.4
0.6
0.8
1.0
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Questions?