Use of GroundPenetrating Radar forUseofGround PenetratingRadarforPavementAssessmentandEvaluation

DavidHernando

TTE5837PavementManagement

G i ill (FL) D b 2012Gainesville(FL),December2012

Outline

1. Definition

2. Characteristics

3. Basicprinciples

4 E i t4. Equipment

5. Permittivityandwavepropagationy p p g

6. Applications

7. Limitations

l8. Summaryandconclusions

9 References9. References

1.Definition

GPRisahighresolutionelectromagnetictechniquethat is designed primarily to investigate the shallowthatisdesignedprimarilytoinvestigatetheshallowsubsurfaceoftheearth,buildingmaterials,roads,and bridgesandbridges

(Daniels,2000)( , )

2.Characteristics

B d th t i i f l t ti Basedonthetransmissionofelectromagneticwaves(pulsedradiowaves)

Usedforthelast30yearsinpavements Nondestructivetechnique Canbeperformedatnormaldrivingspeeds(nolane

closures or traffic disruptions)closuresortrafficdisruptions)

3.Basicprinciples(i)

El t ti t itt d f t Electromagneticwavestransmittedfromantenna Wave travels through the material: v=fnc( ) Wavetravelsthroughthematerial:v=fnc(r) Wave reaches an object or layer interface (change Wavereachesanobjectorlayerinterface(change

indielectricproperties)

Waveisreflected Reflectedwaveisrecordedbyreceivingantenna:

twoway travel time and amplitudetwo waytraveltimeandamplitude

Dataprocessingp g

3.Basicprinciples(ii)

Time(2way)

t0 t1 t2 t3

Pulsesinmagnitude:changeindielectricproperties Traveltimes:depth

c,speedoflight(3108 m/s)r,relativepermittivitymr,relativemagneticpermittivity(1forsoilandconcrete)rh,depthofobjectorlayerinterfacet,twowaytraveltimeofreflectedsignals

4.Equipment(i)

Radarelectronics Antennas Datadigitizer Computer

l d l Displaymodule

4.Equipment(ii)

A t h t i tiAntennacharacteristics:

Monostatic (transmisor & receiver) or bistatic Monostatic(transmisor&receiver)orbistatic(transmisor+receiver)

Airorground Effectsoffrequency(100MHz 1GHz):

Hi h f hi h l i l i Highfrequency:highresolution,lowpenetration

Lowfrequency:lessresolution,greaterpenetration

4.Equipment(iii)

Groundcoupled AircoupledGround coupled(PopikandRedman,2006)

Air coupled(EdwardsandAlexander,2005)

5.Permittivityandwavepropagation

Permittivity can be obtained by:Permittivitycanbeobtainedby: Laboratorymeasurements(percometer) Fieldmeasurements(reflectedamplitude) Typical values for pavement materialsTypicalvaluesforpavementmaterials

P i i i d dPermittivitydependson: Temperature Moisturecontent Salt content Saltcontent Distresslevel Ageatearlystages(cementtreatedmaterials)

5.Permittivityandwavepropagation

Typical values for pavement materials:Typicalvaluesforpavementmaterials:

Material Relativepermittivity(r)p y ( r)Air 1Water 81HMA 57PCC 79Flexiblebase 620Subgrade 1025Subgrade 10 25Asphaltbinder 2.1Dry aggregate 46Dryaggregate 4 6

(ScullionandSaarenketo,1997)

6.Applications(i)

St d i th lif l f dStagesduringthelifecycleofaroad:

Quality control/Quality assurance (QC/QA) Qualitycontrol/Qualityassurance(QC/QA) Pavement monitoring Pavementmonitoring Rehabilitation designRehabilitationdesign Damageandforensicanalysisg y

6.Applications(ii)

Specific applications:Specificapplications:

Determinationoflayerthicknesses Detectionofstrippinginasphaltlayers Locationofvoids Presenceofmoistureunderthepavement Detection of subsurface anomalies: cracking Detectionofsubsurfaceanomalies:cracking,

segregation,changesindensity,changesint t t i i t hpavementstructure,previousrepairpatches

Detection of steel rebars and dowelsDetectionofsteelrebarsanddowels

6.1.Layerthickness(i)

M t t i li ti f GPR MostextensiveapplicationofGPR Nondestructive operated at normal driving speedsNon destructive,operatedatnormaldrivingspeeds Usedasaninputforfallingweightdeflectometer Thicknessisdeterminedbymaterialpermittivity

( lib ti t i ll d)(calibrationcoresaretypicallyused)

Signal reflection at PCCgranular subbase may notSignalreflectionatPCC granularsubbasemaynotresultclearenough(similarpermittivity)

Goodaccuracy

6.1.Layerthickness(ii)

A f l thi k tAccuracyforlayerthicknessmeasurements(Maser,1996)

Layertype Deviation

New asphalt 35%

Existing asphalt 510%

Concrete 510%Concrete 5 10%

Granular base 815%

6.2.Voiddetection

QA/QC i h lt i t (d it ) QA/QCinasphaltmixtures(density) Voids under concrete slabsVoidsunderconcreteslabs

(T DOT 2010)(TxDOT,2010)

6.3.Steelrebarsanddowels

(Maser,2002)

6.4.Jointsandreflectivecracking

(PopikandRedman,2006)

6.5.Presenceofmoisture

(Rister,unknown)

6.6.Conditionmaps

Based on changes in dielectric properties:Basedonchangesindielectricproperties: Excessivemoistureinfiltration

Highairvoidcontent

(Maser,2002)

6.7.Changesinpavementstructure

Basedonchangesinreflectionpattern

(PopikandRedman,2006)

(Ed d d(EdwardsandAlexander,2006)

7.Limitations

Timedependent,recordedresponseofthesubsurfacematerialstothepropagationofelectromagneticwaves(notapicture)

Requiressufficientcontrastbetweenlayerdielectrictiproperties

Dielectric properties are not constant (moistureDielectricpropertiesarenotconstant(moisture,temperature,saltcontent,age,distresslevel)

ThinlayersaredifficulttoestimateL f th t i l diffi lt t Layersofthesamematerialaredifficulttodifferentiate

Resultsareoperatordependent

8.Summaryandconclusions

GPR is a nondestructive technique GPRisanondestructivetechnique Canbeoperatedatnormaldrivingspeeds Basedonelectromagneticwavepropagation Requiressufficientcontrastbetweenlayerdielectric

constants

Dielectricpropertiesarenotconstant(moisture,saltcontent age distress level)content,age,distresslevel)

Manydifferentapplications,butalsosomelimitationsy pp , Itisaresponse,notapicture

9.ReferencesDaniels,J.J.(2000).GroundPenetratingRadarFundamentals.Appendixtoareporttothe

U.S.EPA,RegionV.OhioStateUniversity.

Edwards,L.;Alexander,D.R.(2005).GroundPenetratingRadarApplicationsfortheAssessmentofPavements.TriServiceInfrastructureSystemsConferenceandExhibition:ReEnergizingEngineeringExcellence.St.Louis,MO.25August.

Maser,K.R.(1996).EvaluationofPavementsandBridgeDecksatHighwaySpeedUsingGroundPenetratingRadar.Proceedings,ASCEStructuresCongressXIV. Chicago,IL.1518Apr.

Maser K R (2002) Use of GroundPenetrating Radar Data for Rehabilitation of CompositeMaser,K.R.(2002).UseofGround PenetratingRadarDataforRehabilitationofCompositePavementsonHighVolumeRoads.InTransportationResearchRecord:JournaloftheTransportationResearchBoard,No.1808,pp.122126.TRB,NationalResearchCouncil,Washington,D.C.

Popik,M.;Redman,D.(2006).UsingGroundPenetratingRadarasanAssessmentMethodologyinRoadwayRehabilitation.AnnualConference&ExhibitionoftheTransportationAssociationofCanada.Charlottetown.

Rister(unknown).GroundPenetrationRadar(GPR).ApplicationsinKentucky.KentuckyTransportationCenter.

Scullion T ; Saarenketo T (1997 ) Using suction and dielectric measurements as performanceScullion,T.;Saarenketo,T.(1997.)Usingsuctionanddielectricmeasurementsasperformanceindicatorsforaggregatebasematerials.InTransportationResearchRecord:JournaloftheTransportationResearchBoard,No.1577,pp.119138.TRB,NationalResearchCouncil,Washington,D.C.

TxDOT.(2010).UsingGroundPenetratingRadar(GPR)TechniquestoDetectConcealedSubsurfaceVoids.TexasDepartmentofTransportation.

Questions?

Thanks for you attention!Thanksforyouattention!

DavidHernando