State-of-Practice on the Use of

Geosynthetics in Roadway

Applications

Mark H. Wayne, Ph.D., P.E.

Tensar International

mwayne@tensarcorp.com

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?