State-of-Practice on the Use of Geosynthetics in Roadway ......2012/11/06 · BEFORE Subgrade...
Transcript of State-of-Practice on the Use of Geosynthetics in Roadway ......2012/11/06 · BEFORE Subgrade...
State-of-Practice on the Use of
Geosynthetics in Roadway
Applications
Mark H. Wayne, Ph.D., P.E.
Tensar International
30+ YEARS
Foundation & Pavement
Optimization
FEDERAL HIGHWAY ADMINISTRATION
Why Geogrids?
• Construction Platform
• Paved Road
Flexible Pavement Design
BEFORE Subgrade Stabilization Geogrid
Traffic Course Geogrid
12” PennDOT 2A Mod.
12” PennDOT 2A Mod.
AFTER
SEPARATION
Interface Immobilization
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
… 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
Subgrade Particles Cannot Infiltrate Aggregate
Fill Just as Marbles Cannot Infiltrate Tennis
Balls, Provided They Don’t Move.
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
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.
AGGREGATE INTERACTION
FHWA Aperture Size Criteria
Aperture size > D50 of Aggregate Fill
and < 2D85 of Aggregate Fill
UNPAVED ROAD DESIGN
Full Scale Testing Required to Calibrate and Validate
• 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
PAVED ROAD DESIGN
AASHTO ‘93
MEPDG
AASHTO STANDARD PRACTICE
Roadbed Adjustment Reliability Adjustment
On site performance equation
AASHTO 93
PAVED ROAD DESIGN
Converted to a layer depth using coefficients. SN = a1D1 + a2D2m2 + a3D3m3 + …
PAVED ROAD DESIGN
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.
Service Life*
*Courtesy Applied Research Associates, Inc.
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)
• Full-Scale Testing
Performance Evaluation
• Full-Scale Testing
Performance Evaluation
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
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
• Use of Performance Based Testing
Flexible Pavement Design
SN = a1D1 + a2D2m2 + a3D3m3 + …
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
• Optimize Pavement Foundation
▫ Design Stabilization Platform
▫ This is a Stabilization Layer
• Optimize Pavement
▫ Design Base Course Stabilization Layer
▫ Full Scale Testing for Support
Summary
• Laboratory Performance Testing
▫ T307 Resilient Modulus
• Construction QC/QA
▫ Intelligent Compaction
▫ Dynamic/Static Plate Load Testing
Future Practice
T307 Triaxial Cell
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)
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
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
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
IOWA STATE UNIVERSITY Civil, Construction & Environmental Engineering
RICM and PLT Seminar – David J. White 45 11/6/2012
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
Questions?