airport pavement jointing - American Concrete Pavement Association

AIRPORT PAVEMENT JOINTINGGood Practices = Good Performance

Airport Pavement JointingGreg DeanDirector of AirportsAmerican Concrete Pavement AssociationSoutheast ChapterGDEAN@PAVEMENTSE.COM919.772.6648www.pavementse.comOctober 21, 2008

A Cost-Effective PavementThat Meets / ExceedsAnticipated Design Life

Over-Designing is not the answerMore is not always better…• Extra Thickness• Extra Strength• Extra Reinforcement or Dowels• Extra Base (Depth or Strength)Good Jointing practices will lead to goodperformance

Less than 1 year Old…Design Issue?Construction Issue?Combination?

Good Designs = Good PerformanceConstructed in 1953PCI = 97Brunswick – Golden Isles

Good Designs = Good PerformanceConcrete vs. AsphaltForty years older than AsphaltBQK Pavement Performance ComparisonAsphaltConcretePC CI Rating1009080706050403020100979695 96.497067.8364Apron RW TW Total

Why the difference?McKinnon – St. Simons IslandApron PCI = 20Shattered slabs

Performance – Why thedifference?• Similar Materials• Similar Thickness (10”)• Similar Base (stabilized)• Similar il LoadingPCI = 9712.5 x 15 feetVery differentJointing PatternPCI = 20~ 25 feet

Principles of DesignLoad stressTCurling and WarpingVolume ChangeJointSpacing

Jointing Purpose• Limit slab stress• Construction increments• Allow slab movement• Provide load transfer• Provide crack that can be maintained

Crack Formation-3/8 in.100 ftDrying Shrinkage-3/8 in.Thermal ContractionRestraintRestraintCurling/Warping± 20 ft

Shrinkage (cycle)Curling: caused by temperature gradientWarping: caused by moisture gradientCool Top/dryingWarm Top/wetting

What Causes Curling?DayTensionCoolHotWeight of slabNightCompression

Crack Formation-3/8 in.100 ftDrying Shrinkage-3/8 in.Thermal ContractionRestraintRestraintCurling/Warping± 20 ft

Where Does Restraint Come• SubbaseFrom?• Friction (higher the stiffness > restraint)• Unevenness• Voids• Slab edges (fill-in lanes)• Friction• Dowel bars or tiebars

Solution is Controlled Cracks(Joints)• Spacing & type• Vertical work• Thickness• Shrinkage• Load transfer req’t• Steel content• Base material(pavements)• EOR specify jointlocation/type• Pavements• Specify spacing &type but be flexibleof location• Depends onconstruction methods

Considerations for Jointing• Joint Spacing• Joint Type• Dowels• Sealing

FAA Maximum Joint SpacingSlab ThicknessTrans.Long.60 6.07.0-9.09.0-12.0>12.0inch12.512.515.0 15.020.0 20.025.0 25.0feetFAA AC 150/5320-6D Table 3-11

Stabilized or OverlayML = T x CSSlab ThicknessTrans.Long.60 6.08.010.0>12.0inchMax10.00 12.512.5 12.515.0 12.520.0 20.0feetML = Max. Length between jointsT = Slab ThicknessCS = Support Constant• Use 24 for granular subbases• Use 21 for stabilized oroverlays

Joint Types• Contraction (Shrinkage or Control)• Construction

Contraction Joints

Contraction Joint DetailsDoweledPlain

Jointing Begins With A SawcutGranular SubbaseStabilized Subbase• T/4 Saw Depth• T/3 Saw Depth• Bond BreakerOther Considerations:• Saw Timing• Concrete AggregateLimestoneSiliceous GravelTemperature Sensitivity

DoweledConstructionJoints

Construction JointSmooth DowelSeal ReservoirT/2TSmooth Face (Butt Joint)

Dowel Hole Gang Drill

Doweled Contraction JointsDoweled

Airport Dowel DimensionsSlab Thickness Dia. Length. Space6.0-7.080-12 8.0 12.013.0-16.017.0-20.0021.0-24.0inches0.7510 1.01.25150 1.502.0018.018.020.020.0024.0inches12.012.015.018.018.0

Where to Use Dowels...• Longitudinal construction Joints• Certain transverse expansion joints• Last 3 transverse contraction ti jointsfrom free edge (i.e. runway ends)AC 150/5320-6D339. Jointing Steel: Where used. Provisions for loadtransfer by dowels is provided at all transverse expansionjoints and all butt-type construction joints. Dowels forcontraction c o joints should be provided at least three jointsfrom free edge. Contraction joints in the interior may be thedummy groove type (type H).

Isolation/Expansion JointsDoweledCapThickenedEdge1.25TFiller

Isolation Joints• Separate pavement segments ofdissimilar movement (axis)• use bird’s eye view• Where future pavement might beexpected• At Pavement Penetrations

Where to Isolate...DifferentMovementAxis

Pavement Penetrations

Filets...

Filet DetailsThickened Edge JointPerpendicularto edge2 ftOptional Location

Odd-shaped Panels in Filets• Add steel reinforcement (mesh)• 0.05% by cross-section in bothdirections minimum

Fillet Details

Joint Layout PatternConnectorIsolationDoweled ContractionDoweled ConstructiontiRunwayContractionTaxiway

Don’ts

Construction Joint DetailsSeal ReservoirKeyedT/2TFAA AC/150-5320-6D - Do not use for pavementFAA AC/150 5320 6D Do not use for pavementless than 9-inches. Not recommended for use atairports with wide-body traffic.

Bad Male Keyways

Don’t bringa joint tothe edgeofpavementon anangle

Don’tplacebars tooclosetogether!

Don’tdrill adowelhole intoanotherjointface

Summary• Watch your panel size (smaller isbetter)…especially with stiffer, highfriction support/bases• Ideally, be square• Keep ratio (slab L : slab W) to 125%• Look for opportunities to optimize:• Paving lane widths…be flexible• Aggregate interlock has provenperformance for airfield pavements

Thank YOUGREG DEANDirector of AirportsAmerican Concrete Pavement AssociationSoutheast ChapterGDEAN@PAVEMENTSE.COM919 772 919.772.6648www.pavementse.com

Temp Effects on VolumeChangeTemperaturePlastic Autogenous DryingEvaporation Emptying py of Capillaries DryingTime

Load stresses in rigidpavement• Temperature• Creep & Shrinkage• Curling & warping• TrafficTraffic LoaddyEh23 2M = EIM =22dx12 (1 − μ2 )dxMoment – CurvatureEquivalent to(Beam)Moment – Curvature(Slab)dw

W3l2l1ll=4Eh3212 (1 − μ)k