Andrew W. Isenhour, PEMid-Atlantic Regional ManagerNC/SC/VA

TensarTriAx Geogrid

&New Advancements in OnsiteValidation of Designs (APLT)

Who We Are

Tensar Corporation is the parent company of severalwholly-owned, market-leading subsidiaries including:

Tensar International Corporation Geopier Foundation Company North American Green

Tensar Group Overview

Subgrade Stabilization Pavement Optimization Pavement Interlayers Rail Section Reinforcement Foundation Improvement Pavement Drainage Layer

Geopier Foundations Grade Separation

Sierra System SierraScape System Mesa System ARES System

Triton Marine Mattresses Waste Containment &

Capping

Erosion Control Blankets Turf Reinforcement Mats Hydro Seeding Sediment Control Geotextile Tubes Scour Protection Mats

New Construction

Re-Construction

Rehabilitation

Roadways System Overviews

How Geogrid Works

What is geogrid? Why TriAx?

Case History

TX Geogrid Applications

Research Review

Questions & Answers

Agenda

Tensar UX Geogrids(HDPE)

Geogrids Different Types

Tensar TX/BX Geogrids(PP)

Tensars Manufacturing Process

Aperture Size & Interlock

Demonstration of Aggregate Confinement

Development Objective:Better Geogrid

VerticalMembrane support

Membrane tension

Tension Membrane Effect

Stiffness helps protect existing subgrade strength

Tension Membrane Effect

Reinforced Shear Surface

Unreinforced Shear Surface

Improved Bearing Capacity

Confinement of theaggregate base duringloading

Results in increase inSTIFFNESS of the basematerial

Improved/reduced verticalstress distribution applied topavement subgrade

Lateral Restraint Due toFriction

Lateral ShearFlow

Figure 1. Lateral restraintreinforcement mechanism.

Source: USACOE ETL 1110-1-189

Lateral Restraint

Research to Quantify Benefits

KEEP IN MIND

NO TWO GEOGRIDS PERFORMTHE SAME!!

Research & Testing

Research & Testing

Aggregate Rutting Profiles SS

Unreinforced3,000 axle passes

Tensar BX Geogrid10,000 axle passes

Tensar TX Geogrid10,000 axle passes

A Better Mousetrap - SS

Unreinforced3,000 axle passes

Tensar BX Geogrid10,000 axle passes

Tensar TX Geogrid10,000 axle passes

Roadway Applications: Definitions

Used to provide a competent temporary roadsurface or a stable foundation layer for apermanent road when weak subgradeconditions are encountered.

Subgrade Stabilization

Pavement Optimization

Enhanced performance or thicknessreduction of a permanent road whenconstructed on a relatively firm foundation.

So What?How to Design with Geogrid?

Subgrade Stabilzation

Giroud-Han Design Method

Design Method

Quantifying Subgrade Strength

Mechanical Subgrade Stabilization

Unstabilized Mechanically stabilized withgeogrid

Unstabilized BX Type 1 BX Type 2 TriAxTX160

21 inches 15 inches 10 inches 6 inches

GivenInformation:

Rut Depth = 1.5 in.

Axle Load = 18 kips

Tire Pressure =80 psi

No. of Passes = 1200

Sub base CBR = 20(min.)

Subgrade CBR = 1.6(min.)

Example of Potential Savings with TriAx

Geogrid Applications

Reduced Initial CostLife Cycle Cost Savings

Pavement Optimization

Flexible Pavement Design

Research USACE Phase I Phase II Phase III

Designed based on ASHTO methodologies: AASHTO 1993 AASHTO MEPDG

Validation ARA APLT

Mechanically Stabilized Layers (MSLs)USACE Full Scale Studies

Full-Scale testing

2 phases: Phase 1: CBR=3% Phase 2: CBR=6.5% Phase 3: Reconstruct Phase 2

Control vs. MSL

Further develop design database

AASHTO 93 design

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Significant procedures in place toreduce variability in testing (subgrade,base, asphalt, climatic impacts,). APTtesting is much more accurate thanmost field testing.

Click above to go to:https://www.youtube.com/watch?v=LIXcj9uqHlU

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

ControlSections

Stabilized Report Item 1

Report Item 4

Report Item 5

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Heavy Vehicle Simulator(HVS-A). Capable of

applying loads between10,000 and 100,000 lbs.

Uniformly distributedtraffic load with typical

wander introduced.

Research OrganizationUS Army Corps of EngineersEngineer Research and Development Center

Sections Tested2 inches (51 mm) HMA over 8 inches (203 mm) base (control)3 inches (76 mm) HMA over 8 inches (203 mm) base (control)2 inches (51 mm) HMA over 8 inches (203 mm) base over TX140

Testing ConductedThickness Validation & Material CharacterizationInstrumentation of sectionsPavement Characterization (post construction)HVS-A Traffic testing, FWD analysisPost trafficking forensics (in-field CBR, rutting of layers,)

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Key Findings

Control sections rutted quicker than the TX140stabilized section.

Pavement life of the TX140 stabilized sectiondelivered over 18 times the traffic of the controlsection.

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Falling Weight Deflectometer

Tests performed pre-traffic,during trafficking and posttrafficking

Impulse Stiffness Modulus(ISM) values were calculatedto determine if the base wasstress weakening orhardening.

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

0

50

100

150

200

250

300

0 20000 40000 60000 80000 100000 120000

FWD

Stif

fnes

s Va

lues

(IS

M)

ESALs

FWD Stiffness Values of the Section As Trafficking Accumulated

TX140 Control (2in) Control (3in)

This is evidence that the geogrid reinforcement not only provided enhancedstiffness to the aggregate base during construction, it also maintained thestiffness of the aggregate base throughout trafficking to the levels tested in thisstudy.

--Corps of Engineers pg. 37

TX Stabilized

Control

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Rutting

Measured at 5 locations alongeach test item

Measurements taken atselected trafficking intervals

Rutting occurred quicker inthe unstabilized sections.

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

1 10 100 1000 10000 100000

Applied ESALs

Rut

Dep

th (i

n.)

Item 1 (TX 140)Item 4 (Control)Item 5 (3 in. AC)

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Ruttingincreasesrapidly

Ruttingincreasesmuch slower

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

1 10 100 1000 10000 100000

Applied ESALs

Rut

Dep

th (i

n.)

Item 1 (TX 140)Item 4 (Control)Item 5 (3 in. AC)

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

Summary of Testing

Tensar TX stabilized base can significantly improve theperformance of a pavement by maintaining stiffness of apavement section and reducing rutting at the surface.

At rutting levels of 0.25-0.5 inches, sections stabilized withTensar TX provided over 18 times that of the control, andover 7 times that of adding an extra inch of asphalt.

Full-Scale Accelerated Pavement TestsGeogrid Stabilization of Thin Asphalt Pavements

5,400 passes 12,640 passes 100,000+ passes

Mechanically Stabilized Layers (MSLs)ARA Berg Review/Validation

Third-party review/validationof AASHTO 93 pavementdesign using Tensar TriAxgeogrids

AASHTO 93 Optimization

Design Tools

Design Validation - APLT

Mr Values Are Tested and Verified WithAutomated Plate Load Testing (APLT) The APLT system developed by Professor D. J. White, Ph.D., P.E. (Iowa

State)

Automated Plate Load Testing (APLT)Field Response Summary

Research OrganizationIngios Geotechics, Inc.

Section Tested6-inches of base over TX5

Testing ConductedMr of the mechanically stabilized base courseMr of the subgradeMr composite modulusModulus of subgrade reaction (k)ev1 and ev2 strain modulus testingResilient deflections (scaling exponent)

Automated Plate Load Testing SummaryHunt Highway, Arizona

0.12

0.22

0.31

UnstabilizedValue

SP4 MSL DesignValue

Verified MSLValue

Laye

r C

oef

fici

ent

Tensar TX5 APLT FieldValidation

$118,000in savings

113% lifeextension

Mr (Ave) base 155,694 psi

Mr (Ave) subgrade 16,144 psi

Mr (Ave) composite 34,251 psi

Ev2 (top ofstabilized base)

15.23 ksi

Ev2/Ev1 Ratio 1.60

K-value (stabilized) 392 pci

Savings >$118,000 for both sections.Actual APLT results showed a layer coefficient of 0.31

providing 113% greater anticipated design life.

Actual Tested Values of theStabilized Pavement

Automated Plate Load Testing SummaryHunt Highway, Arizona

Paved Fire Access Lanes

Geogrid Applications

Support Beneath Utilities

Geogrid Applications

Support Beneath Utilities

Geogrid Applications

58

Wesleyan Drive

Tensar TX5 Reduced

Undercut asVEP Reduced 8 of

granular fill(undercut)and placedTX5 directlyunder21A/21B

59

Commander Sheppard

Severepumping andrutting insubgrade Test sections

were installeddue topumping

60

Commander Sheppard

Tensar TX160 18-24 Fill Fill reduced

wheresubgradeimproved

61

Princess Anne

Tensar TX5 Reduced

PavementSection asVEP Reduced 1 of

21A/21B &2 of asphalt

Coal Ash Applications - Ash PondCapping

Questions?

Andrew W. Isenhour, PEMid-Atlantic South Regional Manager

NC SC VA - DC843-819-2867 cell

Aisenhour@tensarcorp.comwww.tensarcorp.com