Use of Ground‐Penetrating Radar for Use of Ground Penetrating Radar for Pavement Assessment and Evaluation David Hernando TTE 5837 Pavement Management Gi ill (FL) D b 2012 Gainesville (FL), December 2012
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