managing density for asphalt pavement - apa density presentation_jones_ver4.pdf · cost of...
TRANSCRIPT
-
ManagingDensityFor
AsphaltPavement
1
-
Densityvs.
PavementPerformance
2
-
CostofCompactionCostofCompaction
Leastexpensivepartoftheprocess
Compactionaddslittletothecostofatonofasphalt
-
ImportanceofCompactionImportanceofCompaction
Nf = -1361.88*AV2 + 15723.35*AV + 88162R2 = 0.98
60,000 70,000 80,000 90,000
100,000 110,000 120,000 130,000 140,000 150,000 160,000
0.0 5.0 10.0 15.0
Fatig
ue L
ife, c
ycle
s
Air Voids, %
Effect of Percentage of Air Voids on Fatigue Life20C, 500 microstrain UKAIStudy
1.5%increaseindensityleadsto10%increaseinfatiguelife.
-
FieldDensityTesting
5
-
QualityControl&AcceptanceofJointDensity
DensityGauge 6inchCore
-
CompactionofHMAPavements
Coresdeterminedensity Qualitycontrol Payment Differentfromnuclear Correlatereadings
25mm(1")
-
CompactionofHMAPavementsNucleargauges Setuprollingpattern Usedforqualitycontrol Adjustrollingwhen
Mix Conditionschange
-
FactorsAffectingCompaction
9
-
FactorsAffectingCompactionFactorsAffectingCompaction
MixProperties Aggregate Asphalt Air(Volumetrics) MixTemperature
LiftThickness
Subgrade&BaseSupport
EnvironmentalFactors
TypeandSizeofRoller,#ofPasses
-
EffectofAggregateEffectofAggregate
Gradation Continuouslygraded,gapgraded,etc.
Shape Flat&elongated,cubical,round
SurfaceTexture Smooth,rough
Strength Resistancetobreaking Abrasion
-
AggregateTypes
Natural Processed Synthetic
Round(uncrushed) SingleCrushedFace MultipleCrushedFaces
-
Mixtures Compactionvaries Adjustthicknessforrolldown
Matchmatthickness
AsphaltMixtures
-
PerformanceGradedBinders
PG6422
PerformanceGrade
Average7daymaxpavementtemperature
Minimumpavement
temperature
147.2F 7.6F
-
LoadingRateofLoading
Example Mainlinepavement
PG6422
TollboothPG7022
WeighStationsPG7622
70mph
Slow
Stopping
-
EffectofTemperatureMatTooHotEffectofTemperatureMatTooHot
Bulgesinfrontofdrums Mixmoves&willnot
compact RollerleavesdeepmarksSolution Staybackfrompaver Allowmattocool(stiffen)
-
EffectofTemperatureMatTooColdEffectofTemperatureMatTooCold
Lowerlimit180o F Noadditionalcompaction
Noaggregatemovement Crushingaggregate
Solutions Closertopaver
Slowpaver Addrollers
Increasemixtemp
-
EffectofLiftThicknessEffectofLiftThickness
Optimumliftthickness 4xNominalMaximumAggregateSize(NMAS)
Acceptableliftthickness=3xto5xNMAS ProblemsCompacting
2xNMASorless 6xNMASormore
Especiallycriticalpavingonunevensurfaces
-
Superpave MaxSize,Designation mm
37.5mm 50.025.0mm 37.519.0mm 25.012.5mm 19.09.5mm 12.54.75mm 9.5
Remember:
AsphaltMixDesignation
-
30
20
10
01 2 3 4
TimeforC
ompa
ction,m
in
CompactedThickness,in
30F60F90F
MS22QualityConstructionTable6.03(b))
Increasingtheliftthicknessbyinchadds67minutestoavailablecompaction
time.
LiftThickness
-
EffectofSubgrade&BaseSupportEffectofSubgrade&BaseSupport
Goodsupportcriticaltoobtainproperdensity
Spongyorunstablesupport
Provideslittleresistancetotherollers
Mixturenotconfined,energydisipated
Mixturemoves&cracksratherthancompacts.
-
EffectofEnvironmentalFactorsEffectofEnvironmentalFactors
Factorsaffectinghowfastthemixcools Affectstimeavailableforcompaction
Ambientairtemperature Temperatureoftheexistingsurface Windspeed Liftthickness Asdeliveredmixtemperature Overcastconditions
-
EffectofEnvironmentalFactorsEffectofEnvironmentalFactors
MinnesotaDOTsPaveCool
Excellenttooltodeterminecompactiontime
Basedallfactors Freedownload
http://www.dot.state.mn.us/app/pavecool/index.html
-
ForcesofCompaction&RollerTypes
24
-
EffectofRollerType,Size,PassesEffectofRollerType,Size,Passes
Rollertypeandsizeaffects:
Magnitudeoftheload Howtheloadisapplied
Numberofpasses: Increasesthedensity Tobreakoverpointaftera#ofpasses
Lowerscompaction Ifcontinued,damagesmat
-
ForcesofCompactionForcesofCompaction
Compactionforces Lowforce
Staticpressure Manipulation
Higherforces Impact Vibration
-
RollerTypesRollerTypes
SteelWheeled Pneumatic Vibratory
-
StaticSteelWheeledRollersStaticSteelWheeledRollers
414tonrollersappliesstaticforce 3Wheel Vibratoryrollersinstaticmode Lighterrollersforfinishrolling Drivewheelmustfacepaver
Climbsuncompactedmix Tillerwheelpushesmix
Drumsmustbesmoothandclean Waterspray&scraperbars Criticalforpolymermodifiers Avoidrollersusedonagg base
-
PneumaticRollersPneumaticRollers
Kneadingactionreorientsaggregate Tirepressures:
~80psi(cold)forcompaction ~50psi(cold)forfinishrolling Rangenottoexceed10psi
Tiresmustbehottoavoidpickup Tiresmustbesmooth notread Notusedfor
Porousfriction SMA Polymermodifiedmixes
-
PneumaticRollersPneumaticRollers
Forceis: Weightontiredividedcontactarea ExpressedasPSI
ChangePSIbychanging: Tirepressure Ballast
Lowtirepressure Lowforce
Hightirepressure Highforce
-
PneumaticRollersPneumaticRollers
Frontrearaxlesoffset Manipulatesmix Under&betweentires
Tightenfinish Toresistmoisture
Loweringpressure Increasesmanipulation
Increasingpressure Increasesstaticforce
-
PneumaticRollersPneumaticRollersKeeptireshotandclean: Driveback&forthoncoldmat
Upto30minutes Internallyheattires
Keepmovingtokeeptireshot Skirtsmaybeneededtoretainheat Scrubbersmustbeused
Knockoffanyaccumulation Onlyusereleaseagent
Oncepickupstarts Markswillnotcomeout Tiresdifficulttoclean
-
VibratoryRollersVibratoryRollers
Commonlyusedforinitialrolling Breakdown Largestcompactionincrease
Heavy rollers Heavydutycomponents&frames 818.5tons,5784inwide 50200lbs/linearinch(PLI)
Frequency:27004200impacts/min Amplitude:0.0160.032in
Thinoverlays(2in) Lowamplitudeorstaticmode
Operateatleast10impacts/foot 24mph
-
VibratoryRollersVibratoryRollers
Effectiveness Movementofdruminitiatesparticlemotion Whenparticlesaremoving
Resistancetodeformationisreduced Forceappliedbyweightofdrumplusinertia
Producesagreatercompactiveeffect Achievingmorecompactionperpassthanstaticrollers
-
VibratoryRollers AmplitudeVibratoryRollers Amplitude
Spinningeccentricweightcausesdrummovement
Fallingdrumaddstocompactiveforce
Distancedrummovesiscalledamplitude
Amplitudedeterminesimpactforce
HighAmplitudeLowAmplitude
-
VibratoryRollers AmplitudeVibratoryRollers Amplitude
Amplitudetoohigh Travelspeedtoofast Vibratingcoolmat
Rollclosertopaver Finishrollingtoocool
Rollclosertointermediateroller
Finishrollertoolight
-
VibratoryRollers FrequencyVibratoryRollers Frequency
Frequency Drumimpacts
perminute Matchtravelspeed
tofrequency Bestresultswhen
impactspacingis1014perfoot
-
VibratoryRollers FrequencyVibratoryRollers Frequency
VibratingReedTachometer Checkstheaccuracyoftherollersfrequencyreading Containsagroupofreedswithaspecificnaturalfrequency AsasinglevibratingdrumpassesVRT
Observewhichreedisvibrating Checkvalueoffthemachinetachometer
-
VibratoryRollers FrequencyVibratoryRollers Frequency
-
DrumImpactsperFootDrumImpactsperFootFrequency 2 MPH 3 MPH 4 MPH 5 MPH2000 vpm 11.36 7.58 5.68 4.552200 vpm 12.50 8.33 6.25 5.002400 vpm 13.64 9.09 6.82 5.452600 vpm 14.77 9.84 7.39 5.912800 vpm 15.91 10.61 7.95 6.363000 vpm 17.05 11.36 8.52 6.823200 vpm 18.18 12.12 9.09 7.273400 vpm 19.32 12.88 9.66 7.723600 vpm 20.45 13.64 10.22 8.183800 vpm 21.59 14.39 10.80 8.634000 vpm 22.72 15.16 11.36 9.10
-
SequenceofRollerOperations&
RollerProcedures
41
-
SequenceofRollerOperationsSequenceofRollerOperations
BreakdownRolling IntermediateRolling FinishRolling
-
RollerOperations TemperatureZonesRollerOperations TemperatureZones
CompactiveForce
PressureImpactVibration
PressureManipulation Pressure
TemperatureRanges
300 260F 250 220 F 200 180 F
-
BreakdownRollingBreakdownRolling
Initialcompactionoperation Getsmostofthedensity Beginathighesttempwithoutmatdistortion
Workcloselytopaver Dualdrumvibratoryworksbest
Bothdrumspowered Pressure Impact Vibration
-
BreakdownRollingBreakdownRolling
Traditionally3wheelsteel D/Dvibratorymostcommon Vibrationmostproductive
duringbreakdown Pneumatics
Usedonbasecourses Levelingcourses
Forcesmixintocracks Compactswithoutbridgingminorruts
Leavedeepmarks hardtorollout
-
IntermediateRollingIntermediateRolling
Finalstepingettingdensityandinitialsmoothness Mathotenoughtoallowaggregatemovement Matalreadyclosetofinaldensity Toomuchforcewillfractureaggregate Typicalrollertype:
Traditionallypneumatic Vibratoryatlowamplitudeand/orstaticmode
-
FinishRollingFinishRolling
Mainpurpose Minimalcompaction Smoothness Removalofanymarks Oncesmooth,stoprolling
Typicalrollertypes: Tandemsteelwheel Pneumaticw/lowerpressure Vibratorystaticmodeonly
-
Den
sity
0 1 2 3 4 5# Passes
EstablishingRollingPattern
-
RollingPattern
Speed&lappatternforeachroller Numberofpassesforeachroller
Onetripacrossapointonthemat Setminimumtemperatureeachrollerfinishespattern
IMPORTANT: Paverspeedmustnotexceedcompactionoperation!!!
Pavermakessinglepass Rollerpatternrequires37passes
-
GeneralRollingProcedures
ReversingDirections Avoidstraightstops Turntowardcenterofmat Dontturndrumwhilestopped Nextpassshouldrolloutanymarkscreatedbyreversing
-
GeneralRollingProceduresGeneralRollingProcedures
Forbestresults Rollathighesttemperaturewithoutexcessivedisplacement
Stayclosetopaver Monitorweather
Keepupbutnottoofast Adj paverspeed
-
GeneralRollingProceduresGeneralRollingProcedures
152 mm (6")
Overlaps 6 overlapassuresuniformcompaction
Includeoverlapwhenselectingdrumwidth
Rollershouldcovermatin3overlappingpasses
-
GeneralRollingProceduresGeneralRollingProcedures
Rolldown Paverlaysthickerlift Rollercompactstothedesignthickness
Superpavemixesrolldown~25%
SMA,PFC&otheropengradedmixesrolldown~15%
-
GeneralRollingProceduresGeneralRollingProcedures
RollingaCrown Neverstraddlecrown Workfrombottomtowardcrownbothsides
Strengthensmattosupportrolleronslope
Overlapcrown6 onlastpass
-
GeneralRollingProceduresGeneralRollingProcedures
Parking Neverparkonahotmat Leavesatransversebumpthatcannotberolledout
Whenservicing: Rollbacktocoolermat Servicevehiclesonmat
-
AchievingDensityonHMAJoints
56
-
LongitudinalJointTypes
NotchedWedge
Butt
-
ButtJoint(paverconstruction)
ButtJoint(milledorcutback)
NotchedWedgeJoint
LongitudinalJointTypes
-
ProperOverlap: 1.0+ 0.5inches
Exception:Milledorsawedjointshouldbe0.5inches
Rolldown 1525%basedonmix
-
Roller
6
4 6
4 6
Option1Hangover46
Roller
Roller
Option21st Pass46inside
2nd Passhangover46
RollingUnsupportedEdge?
-
Option11stPassHangsOver46inches
-
Option2:StayBack46incheson1st pass,thenroll
2nd passw/slightoverhang
Concern: Developingstresscrack?
Merit: Minlateralmovement?
-
DontStarvetheJoint
-
1st passoffthejointapprox68inches
2nd passoverlapsoncoldmat36inches
RollingtheSupportedEdge
-
Roller
Rollerinvibratorymodewithedgeofdrumoverhanging2to4inchesoncoldside.
AlternateMethod1st PassovertheSupportedEdge
ConcernwiththismethodisifinsufficientHMAlaidatjoint,thenbridgingoccurs(rollersupportedbycoldmat)
-
Overlap
-
TransverseJointStartingaLaneTransverseJointStartingaLane
Paver
New Old
150mm(6") Rolltransverse Rollstatic Startdrumoncoldside Moveoverin6 8
incrementsuntildrumisallonhotside
-
TransverseJointStartingaLaneTransverseJointStartingaLane
RollingTransverseJoint
CheckingTransverseJoint
SafetyandTrafficControlConcernsSafetyandTrafficControlConcerns
-
ReferenceMaterialsontheTopic:
MS2: MixDesignMethods
SP2:Superpave MixDesign
MS4: TheAsphaltHandbook
MS22: HMAConstruction
http://www.asphaltinstitute.org
-
ThankYou
WayneJones,[email protected]
70