Gesford - Asphalt Patching · Seminar on Maintenance of Asphalt Pavements Alan L. Gesford, P.E. Technology Transfer Specialist Asphalt Patching Michigan’s Local Technical Assistance

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

uctio

nPr

oduc

tion

Qua

lity

Qua

lity

Production vs Quality

TradeTrade--offs must be balanced!offs must be balanced!

Prod

uctio

nPr

oduc

tion Q

ualit

yQ

ualit

y

Prod

uctio

nPr

oduc

tion

Qua

lity

Qua

lity

Prod

uctio

nPr

oduc

tion

Qua

lity

Qua

lity

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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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“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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“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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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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2. Semi-permanent repairRemove water & debrisSquare up sides, vertical cutsPlace mixCompact - device smaller than patchOpen to traffic

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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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Opposing Demandsgradationaggregate shapeasphalt binderbinder content

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Cold Stockpile MixAsphaltAsphalt

CementCement

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TackingEmulsions:

SS-1SS-1h

Can be used on damp surfaceApply with brush or sprayUse with hot-mix asphalt only

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TackingCutbacks:

Winter Use OnlyBrush or Spray

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Edge SealingEmulsions

SS-1, SS-1hCutback

RC-250, RC-800Asphalt Cement

AC-20

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1. Set-up for Safety2. Marking3. Cutting4. Cleaning

5. Tacking6. Filling7. Compacting8. Edge Sealing9. Cleanup

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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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Marking: Does not have to be square or rectangle

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Cuttingremove all weak, deteriorated areacut…. “vertical sides”

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Vertical Sides for Confinement:

Confinement

Shoving

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Vertical Sides for Compaction:

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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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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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Modification of Marking

Poor BondRemove

Original Mark

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Cutting BitsSharp bits improve productionSharp bits do less damageExchange dull bits

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Cleaningremove loose materialremove waterpay attention to cornersuse air if availableotherwise stiff broom

Remove Failed

Pavement

Remove To Sound Material

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Sometimes the problem may not be evident on the surface.Remove waterAdditional drainage may be required to solve this problem.

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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


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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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FillingShovel or dump material directly in holeTamp material into edges and corners with square-edge shovelMax. lift - 3 inches

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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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Large patches demand large equipment

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Compactionmost importantpoor compaction will give depression under trafficpoor compaction will cause raveling and shoving

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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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For deep patches, each layer (subgrade, subbase, base, paving) requires compaction!

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Compaction

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Compaction

Step 1. Pinch against edges Step 2. Roll patch

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CompactionBridging

Follow Pavement Ruts

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Final Compaction1/4”

Good Compaction

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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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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




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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!

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Thank You!

Alan L. GesfordTechnology Transfer Specialist

E-mail: [email protected]

Documents

Gesford - Asphalt Patching · Seminar on Maintenance of Asphalt Pavements Alan L. Gesford, P.E. Technology Transfer Specialist Asphalt Patching Michigan’s Local Technical Assistance