Gesford - Asphalt Patchingmichiganltap.org/sites/ltap/files/workshops/materials/... · 2015. 7....
Transcript of Gesford - Asphalt Patchingmichiganltap.org/sites/ltap/files/workshops/materials/... · 2015. 7....
Seminar onMaintenance of Asphalt Pavements
Alan L. Gesford, P.E.Technology Transfer Specialist
Asphalt Patching
Michigan’s Local TechnicalAssistance Program
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Agenda1. Asphalt Pavement Patching and
Maintenance Objectives2. SHRP / LTPP
SHRP Studies & ResultsManual of Practice
3. Conventional Patching ProgramMaterialsEquipmentProcedure
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Agenda
4. Alternative InnovationsSelf Contained Patch UnitSpray Injection PatchingInfrared Patching
5. Patching ‘oil & chip” Roads6. Utility Cuts / Trench Restoration
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4 8 12 16YEARS
VERYGOOD
GOOD
FAIR
POOR
VERYPOOR
40% Quality Drop
40% Quality Drop
75% Time
17% Time
Deterioration / RehabilitationRelationship
Deferring Maintenance Equals
Increased Costs
Then
Why Do We Defer?
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Maintenance Objectives vs. Asphalt Patching
Recognize DistressUnderstand CausesKnow Proper MaterialsKnow Proper Steps Consider Repair to be Permanent
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Maintenance Objectives vs. Asphalt Patching
Do It
the First time
Right
RightRight
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WATER, WATER, WATER
Need to take care of all water problems first!
Only then will all other repairs be cost effective!
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Types – Distresses - Repairs
Fatigue (alligator cracks)PotholesDepressionsSlippage RuttingCorrugation/ShovingEdge Deterioration
PatchingFull-Depth PatchingPartial Depth PatchingSurface (Temporary) Patching
Scratch / Leveling Courses (prep for overlay)
Milling
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Types – Distresses - Repairs
RavelingBleedingPolishing
Seal Coats / Surface Treatments
Chip SealsSlurry SealsMicrosurfacingNovaChip
Milling
Cracking Crack Sealing
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2 Main Elements of Asphalt Patching
Material SelectionRepair Procedures
“For each agency, different combinations of materials & procedures will produce optimum cost effectiveness.”
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Pothole Patching Program
1. Set-up for Safety2. Marking3. Cutting4. Cleaning
5. Tacking6. Filling7. Compacting8. Edge Sealing9. Cleanup
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Factors Effecting # of Steps in Pothole Repair
Safety & rideability (existing conditions)Level of trafficVariety of pavement typesTime of year Resources - personnel, materials, equipmentManagement philosophy (or knowledge)Time until overlay or rehabTolerance of public
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Prod
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Production vs Quality
TradeTrade--offs must be balanced!offs must be balanced!
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SHRP/FHWA/LTPP Research
Strategic Highway Research Program
SS
RRHH
PP
Long Term Pavement Performance
LLTTPPPP
Federal Highway Administration
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SHRP Studies
H-105 Innovative Materials & Equipment for Pavement surface RepairH-106 Innovative Materials Development & TestingFHWA Long-Term Monitoring (LTM) of Pavement Maintenance Materials Test Sites
Final Report: LTPP Pavement Maintenance Materials: SHRP Crack Treatment Experiment, Final Report. FHWA-RD-99-142
http://www.fhwa.dot.gov/pavement/pub_listing.cfm?areas=LTPP
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SHRP Studies
“Bituminous hot mix has shown the longest service life of all materials when it is placed using permanent procedures in a dry hole.”
SHRP
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SHRPManual of Practice
Materials and Procedures for
Repair of Potholes in Asphalt-Surfaced
Pavements
Report No. FHWA-RD-99-168
underline
http://www.fhwa.dot.gov/pavement/pub_listing.cfm?areas=LTPP
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SHRPManual of Practice
“The patching operations described in this manual can be performed in any weather.”“The materials and procedures discussed are for cold-mix stockpiled materials and for spray-injection patching devices”“The goal of winter patching is to restore rideability and safety as quickly as possible (not to repair the distress permanently)”
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SHRPManual of Practice
“The use of hot-mix asphalt concrete, although recognized as a preferred alternative for patching operations, is not covered in this manual.”
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SHRPManual of Practice
MaterialsConventional Cold MixesProprietary Cold MixesSpray Injection
……an agency must verify the quality of materials used……..
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SHRP Manual Repair Techniques
1. Throw-and-rollPlace material in holeCompact with truck tiresOpen to traffic
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SHRP Manual Repair Techniques
2. Semi-permanent repairRemove water & debrisSquare up sides, vertical cutsPlace mixCompact - device smaller than patchOpen to traffic
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SHRP Manual Repair Techniques
3. Spray injectionBlow out water & debrisSpray tack on sides & bottomBlow asphalt & aggregate into holeCover patch with aggregate layerOpen to traffic
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Asphalt Patching Programs
Conventional PatchingMaterialsEquipmentProcedures
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Conventional Asphalt Patching Program
Materials:1. Conventional Hot-Mix2. Cold Stockpile Mix3. Tack4. Edge Seal
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Conventional Hot Mix
Stone or + Sand + Asphalt CementCrushed Gravel
Heat and mix in plant @ 380o F
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Cold Stockpile Mix
3/8 in. Stone or + Sand + Emulsion orCrushed Gravel Cutback
Heat and mix in plant @ 140o F
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Asphalt Patching Program
Cold Mix Requirementsa. Pliable in stockpileb. Cannot drain in stockpilec. Easy to shovel & compactd. Retain asphalt coatinge. Stable under traffic
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Asphalt Patching Program
Opposing Demandsgradationaggregate shapeasphalt binderbinder content
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Asphalt Patching Program
Cold Stockpile MixAsphaltAsphalt
CementCement
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Asphalt Patching Program
TackingEmulsions:
SS-1SS-1h
Can be used on damp surfaceApply with brush or sprayUse with hot-mix asphalt only
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Asphalt Patching Program
TackingCutbacks:
Winter Use OnlyBrush or Spray
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Asphalt Patching Program
Edge SealingEmulsions
SS-1, SS-1hCutback
RC-250, RC-800Asphalt Cement
AC-20
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Asphalt Patching Program
1. Set-up for Safety2. Marking3. Cutting4. Cleaning
5. Tacking6. Filling7. Compacting8. Edge Sealing9. Cleanup
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Asphalt Patching Program
Markingform of communicationexcess cutting costs materials & crew hoursinsufficient cutting means poor repairmay need to modify original marking
Marking: May include several adjacent potholes or deteriorated areas
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Asphalt Patching Program
Marking: Does not have to be square or rectangle
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Asphalt Patching Program
Cuttingremove all weak, deteriorated areacut…. “vertical sides”
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Asphalt Patching Program
Vertical Sides for Confinement:
Confinement
Shoving
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Asphalt Patching Program
Vertical Sides for Compaction:
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Asphalt Patching Program
Cutting EquipmentAir compressorHydraulic BreakerGasoline Powered BreakerMilling Machines Saws
Cutting Equipment
Jack Hammer – Air Compressor
Hydraulic Breaker
Cutting Equipment
Gasoline-Powered Breaker Milling Machines
Cutting Equipment
Carborundum Saw
Concrete Saw
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Asphalt Patching Program
Cuttingleave firm material around repairdo not outline area to be cut with cutting tool , begin at center of hole
Do NOT Rock!!
Edge of Hole
Begin atCenter
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Asphalt Patching Program
Modification of Marking
Poor BondRemove
Original Mark
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Asphalt Patching Program
Cutting BitsSharp bits improve productionSharp bits do less damageExchange dull bits
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Asphalt Patching Program
Cleaningremove loose materialremove waterpay attention to cornersuse air if availableotherwise stiff broom
Remove Failed
Pavement
Remove To Sound Material
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Asphalt Patching Program
Sometimes the problem may not be evident on the surface.Remove waterAdditional drainage may be required to solve this problem.
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Asphalt Patching Program
Replace with good material similar to the material in the original pavementDeteriorated aggregate base or subbase material plus subgrade soils may need to be replaced
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• Testing for quality control may be required
Asphalt Patching Program
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Asphalt Patching Program
Tackingtack for hot mix onlylet cure
emulsions - water evaporatescutback - thinner evaporates
Tacking
YES!Spray
YES!Brush
NO !Pour
Thin
Thin
Bead
Puddle
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Asphalt Patching Program
FillingShovel or dump material directly in holeTamp material into edges and corners with square-edge shovelMax. lift - 3 inches
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Asphalt Patching Program
Filling: Use a lute (no garden rakes)
Tamp
Segregation
Maximum Lift 3”
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Asphalt Patching ProgramEquipment: Hotboxes, maintainers, reclaimers
Hot asphalt feed at shovel level for easy access
“The Reclaimer”
Heats cooled hot-mix for reuse
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Asphalt Patching Program
Large patches demand large equipment
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Asphalt Patching Program
Compactionmost importantpoor compaction will give depression under trafficpoor compaction will cause raveling and shoving
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Asphalt Patching Program
Compaction EquipmentVibratory platePortable vibratory drum Self-propelled rollerGasoline poweredHand tamper
Vibratory Plate
Portable Vibratory Roller
Self-propelled
Self-propelled
‘The larger the patch, the larger the compaction equipment needed for proper compaction & rideability’
Gasoline Powered
Hand Tamp
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Asphalt Patching Program
For deep patches, each layer (subgrade, subbase, base, paving) requires compaction!
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Asphalt Patching Program
Compaction
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Asphalt Patching Program
Compaction
Step 1. Pinch against edges Step 2. Roll patch
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Asphalt Patching Program
CompactionBridging
Follow Pavement Ruts
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Asphalt Patching Program
Final Compaction1/4”
Good Compaction
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Asphalt Patching Program
Edge Sealingkeeps water outavoid excess seal materialdo not edge seal cold mixblot if necessary
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RuttingCauses
Consolidation or lateral movement of the subgrade, aggregate base, and/or asphalt layers under traffic.Insufficient design thickness.Lack of compaction.Weakness caused by moisture.Movement of the mixture under heavy wheel loads.
Rutting: Weak Base /Subgrade
originalprofile
weak subgrade or underlying layer
asphalt layer
subgradedeformation
Rutting in the Subgrade or Subbase
Need to Reconstruct (or fill rut & overlay or mill & overlay
to increase pavement thickness)
originalprofile
weak subgrade or underlying layer
asphalt layer
subgradedeformation
Rutting: Weak Asphalt Pavement
Consolidation
originalprofile
weak asphalt layer
Plastic Flow
weak asphalt layer
originalprofile
Need for Scratch & Levelingor Milling
A scratch course is used to fill ruts before placing an overlay
Need for Scratch & Levelingor Milling
A Leveling Course provides a level uniform platform for new paving and insures uniform density throughout the mat.
Need for Scratch, Levelingor Milling
Material milled off prior to placing overlay
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If you do not Scratch, Level or Mill…
Failure to scratch, level, or mill prior to placing the overlay results in areas of greater thickness
and will lead to ……………..
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Failure to Scratch, Level or Mill
... reoccurrence of rutting
Need for Milling & then overlay
Plastic flow material
Lift delineation
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Asphalt Patching Programs
InnovationsSelf-Contained Pothole Patching VehiclesAsphalt Spray Injection PatchingAsphalt Infrared Patching
Self-Contained Pothole Patching Units
Self-Contained Pothole Patching Unit
Cut out deteriorated material (vertical sides)
Remove all loose material
Blow out remaining fine material, dust
Apply tack – watch the overspray!
Fill with hot-mix asphalt from hot box
Compact patch
What’s your Goal?
Nice permanent patch!
Infrared Asphalt Heater
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Asphalt Patching Program
Infrared Asphalt PatchingSurface distress repairSoften existing asphalt area with infrared heat, rake in new material as needed, and compactEliminates cutting out and hauling away deteriorated materialEliminates tack coatingResult is a seamless repair
Infrared Asphalt Heaters
Infrared Asphalt Heaters
Hot -box
Joint Heaters
The infrared heating unitis lowered to within 6" of the pavement.
The infrared heat penetratesthe existing asphalt approximately 2".
Having heated the area to be repaired, the softened asphalt is raked and cleared of
impurities.
Hot asphalt is added toand blended with the original asphalt.
The edges are rolled first to bond the new asphalt with the original asphalt. The entire
area is then compacted.
The repair becomes aseamless part of the original asphalt
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Asphalt Spray Injection Patching
Cleans, tacks, fills and compacts with a one-person operationEliminate ‘cold patch’Year-round emergency adverse weather patchingImproved productivity and safetyUsed for both asphalt and cement concrete pavements
Spray Patchers*Trailer .
*Truck Mounted *Self-Contained
Blow out all loose material
Apply emulsion tack
Fill with aggregate /emulsion mix (No compaction needed)
Finish with a fine cover aggregate if needed
Finished spray patch
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Patching ‘Oil & Chip’ Roads
Build-up “Oil & Chip” Roadsmore flexible type pavementhot-mix may be too “rigid”
Alternate #1Alternate #1
Alternate #1Alternate #1
Alternate #2Alternate #2
Alternate #2Alternate #2
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Utility Cuts / Trench Restoration
Proper Restoration is Necessary!!!Infrastructure InvestmentSafetyLiabilityPublic Relations
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Utility Cuts / Trench Restoration
The GOAL is to restore your street or road to its
Original Condition!
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Backfilling
Fine Aggregate to Protect FacilityAggregate Backfill - Select Granular MaterialFlowable-Fill
Material
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Backfilling
Flowable-Fill(Controlled Low-Strength Material – CLSM)(Low Density Backfill)A blend of cement, sand, water, plus fly ash,
designed as a low strength, flowable material for backfill and other uses
Delivered by cement concrete trucks
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Backfilling
Flowable-Fill AdvantagesSelf leveling, filling all voidsNo placing in lifts, no compaction needed – less equipmentDesigned to allow for re-excavationLoad bearing capacity typically higher than compacted granular backfillRequires less field inspection
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BackfillingFlowable-Fill Spec
Develop specificationMany State DOTs now have spec
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BackfillingExcavated Material for Reuse
3” Maximum SizeNot Water SaturatedReadily Compacted 6 to 8 inch layers –proper moisture contentNo Puddling
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Backfilling
Inspection to insure compacting in layersDensity tests:
95% density – define test methodPermittee responsible for testingLarge projects or deep trenches
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Paving Restoration‘In-kind’ Restoration Final Cut - Shelf Back 6 to 12 inches for Clean EdgeCompacted Asphalt Layers of 3 inches maximumTack Coat - EmulsionsEdge Seal - Emulsions
Select Granular Material
Insulating Material
1’-0”Typ.
Asphalt Base
ExistingAsphalt Base
Asphalt Wearing Course
Typical Final Restoration (Asphalt Base)
Asphalt Surface
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Multiple Excavations4+ in 100 Linear Feet of RoadOverlay total area of all travel lanes affectedMay require milling prior to overlay
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Steel Plates
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Maintaining Traffic
Temporary Plates:Steel protection plates / prefab light weight platesSized to provide adequate bearing at plate edgesSecurely anchoredSufficient thickness to carry heavy trafficExposed plate edges feathered with asphalt
Length of use could dictate milling bearing area & setting plate level with street surface
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H20 Load Rated
Skid Resistant diamond plate surface
Orange color for visibility
Lightweight – carried by one or two people
Different sizes up to 4’x 8’
Comcore
Pre-fab PlatesComcore
Comcore
Comcore
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Pre-fab Plates converted to
Trench Shoring
Pre-fab Plates
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Temporary Restoration
Necessary - wintertimeRequired - anytimeTypical Standard
Select Granular Material
Insulating Material
2” Min. Asphalt Material
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Other Requirements
Test Holes (4 Inch Diameter or Less)Backfill to Meet Existing Materials and Seal
No equipment with metallic treads allowed on road surface or surfaced shoulderMinimum depth of cover (e.g. 3 feet from road surface)
‘Throw and roll’
‘Throw and go’
Is your goal temporary patching?
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Summary
Meet your goals and expectationsUse appropriate materialsUse proper proceduresWork safely
?’sDiscussion!