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MMLS3 users group report TRB 2005

Fred Hugo

Accelerated pavement testing Accelerated pavement testing (APT)(APT) isis ……..the the controlled application of wheel loadingcontrolled application of wheel loading to to a a layered pavement structurelayered pavement structure to determine to determine pavement response and performancepavement response and performance under under controlled, accelerated accumulation of controlled, accelerated accumulation of damagedamage in a in a compressed time periodcompressed time period in field in field or laboratory conditionsor laboratory conditions

Definition of Definition of APTAPT

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Key to application of the MMLS3Key to application of the MMLS3

ØØ Understanding APT, distress mechanisms and Understanding APT, distress mechanisms and performance. performance.

ØØ Accelerated pavement testing Accelerated pavement testing (APT)(APT) beingbeing ……..the the controlled application of wheel loadingcontrolled application of wheel loading to a to a layered pavement structurelayered pavement structure to determine to determine pavement response and performancepavement response and performance under under controlled, accelerated accumulation of controlled, accelerated accumulation of damagedamage in a in a compressed time periodcompressed time period in field or in field or laboratory conditionslaboratory conditions

ØØ Globally there are > 50 papers reporting on Globally there are > 50 papers reporting on different aspects of MMLS3 applications and different aspects of MMLS3 applications and related findingsrelated findings

MMLS3 studies in global MMLS3 studies in global perspectiveperspective

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Currently twelve MMLS3’s globally •Three in South Africa

-Two at Univ of Stellenbosch-One in a SRT commercial lab in Natal

•One in Switzerland-EMPA•One at Worcester Polytechnic Ma – US•One at NCSU NC –US•One at UNH- US •One at U Mass MA - US•Two in Texas Texas A&M Univ/Texas DOT §One going to Republic of China MOC§One going to Penn State - US

MMLS3 field and lab MMLS3 field and lab applications in 3 categoriesapplications in 3 categories

Field rutting and moisture damage

Field & Laboratory

Moisture damage –micro fracturing and surface fatigue

Structural distress of model pavement in laboratory

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Applications FieldApplications Field

Field testing in Namibia

Rut after wet field testing

Latest Latest LaboratoryLaboratoryTest Bed, Test Bed,

ProfilometerProfilometerandand

Water HeaterWater Heater

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Laboratory evidence of stripping

Laboratory studiesWorcester Polytechnic Institute (WPI)

Massachusetts-USA

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Slab separation after compaction

Slab after compaction in laboratory

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Model pavement with Cement Stabilized Base Course

Overview of MMLS3 Testing in 2003/4Overview of MMLS3 Testing in 2003/4

Mozambique Mozambique APT study 2004APT study 2004

Distress Distress mechanisms mechanisms similar to fieldsimilar to field

Performance Performance SandSand CemenCement t Treated Base Treated Base

Wet Lab/ Wet Lab/ Scaled Scaled Structure/SAStructure/SA

ISAP 2002ISAP 2002CAPSA 2004CAPSA 2004

MatlMatl & structural & structural performance performance evaluated for evaluated for modellingmodelling

Performance Performance Related Related Seal Seal DesignDesign

DryLabDryLab//Field Test SA Field Test SA insituinsitu

TRR 2003/TRR 2003/APT 2004APT 2004

ØØHMA wet HMA wet trafficking trafficking distress distress quantified in quantified in stiffness and stiffness and strength loss.strength loss.ØØWet surface Wet surface distress equal distress equal 20% of dry 20% of dry traffictraffic

Performance of Performance of five trial five trial sections sections NCAT NCAT tracktrack in terms of in terms of rutting and rutting and distress due to distress due to wet traffickingwet trafficking

Dry/Wet Field Dry/Wet Field and Lab Tests and Lab Tests --insituinsitu/cores /cores USAUSA

Reference(sReference(s))FindingsFindingsTest GoalTest GoalCase StudyCase Study

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Overview of MMLS3 Testing (cont2)Overview of MMLS3 Testing (cont2)

Contract Contract project report/project report/CAPSA 2004CAPSA 2004

Effect on performance Effect on performance quantified for decision quantified for decision by the highway by the highway authorityauthority

Evaluation of Evaluation of CompactionCompaction and and Lime FillerLime Filler on on performance of new performance of new asphaltasphalt

Dry/Wet Field Dry/Wet Field & Lab Tests & Lab Tests --insituinsitu/cores /cores NamibiaNamibia

••PhD 2003,PhD 2003,••RILEM 2004RILEM 2004••APT2004APT2004

Characterization of Characterization of fatigue performance fatigue performance relative to stiffness loss, relative to stiffness loss, crackingcracking

FatigueFatiguePerformance of Performance of scaled HMA layer scaled HMA layer at at NCSU and WPINCSU and WPI

Dry Lab Tests Dry Lab Tests USA USA -- scaled scaled structuresstructures

IJPE 2004IJPE 2004Relationship between Relationship between transverse deformation transverse deformation due to trafficking and due to trafficking and strain establishedstrain established

FatigueFatiguePerformance of Performance of scaled HMA layer scaled HMA layer at at WPI with focus WPI with focus on transverse on transverse deformationdeformation

Dry Lab Tests Dry Lab Tests USA USA -- scaled scaled structurestructure

Reference(sReference(s))FindingsFindingsTest GoalTest GoalCase StudyCase Study

Overview of MMLS3 Testing (cont3)Overview of MMLS3 Testing (cont3)

CAPSA 2004;CAPSA 2004;APT 2004APT 2004

ØØReinforcing reduces Reinforcing reduces ruttingruttingØØDry foam asphalt rut Dry foam asphalt rut resistantresistantØØMMLS3 MMLS3 vsvs HVS HVS compatiblecompatibleØØConstruction Construction parameters and effect of parameters and effect of aging quantifiedaging quantified

ØØReinforcing; Reinforcing; ØØFoam asphalt Foam asphalt BaseBaseØØProprietary Proprietary MatlsMatls; ; ØØAging; Aging; ØØUse as PPGS tool; Use as PPGS tool; ØØComparison with Comparison with rut testersrut testers

Special Lab Special Lab and Field and Field studiesstudies

Contract Contract project report/project report/CAPSA 2004CAPSA 2004

ØØField mix rutting tests Field mix rutting tests suspectsuspectØØLab briquettes used to Lab briquettes used to validate new HMA validate new HMA designdesignØØField performance so Field performance so far goodfar good

Evaluation ofEvaluation ofAdditiveAdditive and and Mix Mix compositioncomposition on on performance of new performance of new asphalt surfacing and asphalt surfacing and base coursebase course

Dry/Wet Dry/Wet Field & Lab Field & Lab Tests Tests insituinsitu/cores /cores JhbJhb Intl Intl AirportAirport

Reference(sReference(s))FindingsFindingsTest GoalTest GoalCase StudyCase Study

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Load Setting / PSPA at NCATLoad Setting / PSPA at NCAT

NCAT field study Phase 2NCAT field study Phase 2Core holesCore holes

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NCAT HMA damaged by wet traffickingNCAT HMA damaged by wet trafficking

Stiffness loss during trafficking of S9 Stiffness loss during trafficking of S9 NCATNCAT

0%

20%

40%

60%

80%

100%

0 100 200 300 400 500 600 700

MMLS3 axles (Thousands)

Mod

ulus

rat

io

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NCSU model pavement study NCSU model pavement study Tensile StrainTensile Strain--NNff---- VoidsVoids

NCSU model pavement study NCSU model pavement study SASW SASW vsvs CrackingCracking

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WPI fatigue resultsWPI fatigue results

Typical rut development during Typical rut development during heated dry trafficking in field trialsheated dry trafficking in field trials

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ThreeThree--D grid reinforcement D grid reinforcement improving rutting and fatigueimproving rutting and fatigue

--As a tool for evaluation of water susceptibility/ As a tool for evaluation of water susceptibility/ moisture damagemoisture damage--Applications of MMLS3 as a tool for evaluation Applications of MMLS3 as a tool for evaluation of rutting performanceof rutting performance--Relationship slab : cores : briquettes Relationship slab : cores : briquettes establishedestablished

Interim Protocols for Performance Evaluation Established

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MODULAS Sensor Installed In MODULAS Sensor Installed In Pavement Pavement

Contact stress @ 862 Contact stress @ 862 kPakPa tyretyre pressurepressure

0.0

200.0

400.0

600.0

800.0

1000.0

Cont

act

Stre

ss (kP

a)

0 13.2 26.4 39.6 52.8 66 79.2 92.4 106 119 132 145 13

57

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4-80X6Tire (MMLS)

800.0-1000.0

600.0-800.0

400.0-600.0

Inflation Pressure: 862 kPa Temperature : 7º CTest Vehicle Speed: 2.4 m/sMax Stress: 867 kPa

Longitudinal (mm)

Transverse (Sensor No.)

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inflation pressure vs max vertical contact stress

Tair = 7C

0

200

400

600

800

1000

500 550 600 650 700 750 800 850 900

tire inflation pressure (kPa)

max

ver

tica

l co

nta

ct

stre

ss (

kPa)

MLS10 for use in MozambiqueMLS10 for use in Mozambique

SECTION

285/70 R19.5 (°920)

PLAN VIEW

3000

7400

6000

BALLASTTANK

400

8-TON AXLE DRIVEN BY HYDRAULIC MOTOR 8-TON AXLE, STEERABLE

ELECTRIC DRIVE SYSTEM

BALLASTTANK

BALLASTTANK

BALLASTTANK

HYDRAULIC JACK

Under development:

MLS10

2400

8400

Wheel load 12 ton max. per axle/2 = 6 ton max.Application rate: 7200 axles per hour.

MLS10 - a full scaleMobile Load SimulatorAn APT device forevaluation of full-scale pavementstructures in conjunction withthe MMLS3

USING LINEAR INDUCTION MOTORS

4mm COVER PLATES OVERCURVED END SECTIONS

STIFFENING

LINEAR INDUCTIONMOTORS

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MLS10 Characteristics (Mozambique cont)MLS10 Characteristics (Mozambique cont)

ØØMaximum speed 27 Maximum speed 27 kphkphØØNumber of load applications per hour 7,200Number of load applications per hour 7,200ØØWheel load on half axles:Wheel load on half axles:

ll 4 ton 4 ton -- 6 ton (max) on 6 ton (max) on dualsdualsll 5,5 ton on Super single wheels.5,5 ton on Super single wheels.

ØØWheel size, tire type/pressure Wheel size, tire type/pressure ll R19.5 285/70 and R19.5 285/70 and ll Super single 385/65. Super single 385/65. ll Michelin Rated @ 850 Michelin Rated @ 850 kPakPa pressure pressure –– test up test up

to 1,000 to 1,000 kPakPa

ØØThank you for your attention!Thank you for your attention!ØØQuestions?Questions?