MODULE 3-8MODULE 3-8

HMA Pavement HMA Pavement Recycling and Recycling and ReconstructionReconstruction

Learning ObjectivesLearning Objectives

Identify options when pavement is Identify options when pavement is near the end of its service lifenear the end of its service life

Identify considerations associated with Identify considerations associated with reconstructionreconstruction

IntroductionIntroduction

Recycling - A rehabilitation alternativeRecycling - A rehabilitation alternative

Essentially all 50 states use some Essentially all 50 states use some form of recyclingform of recycling

73 million tons recycled annually73 million tons recycled annually

Recycling is not a new conceptRecycling is not a new concept

IntroductionIntroduction

Reconstruction – used less and lessReconstruction – used less and less

Cost Cost

Traffic disruptionTraffic disruption

Recycling vs. Recycling vs. ReconstructionReconstruction

Condition of existing pavementCondition of existing pavement

Traffic levelsTraffic levels

Expected life after treatmentExpected life after treatment

Costs and budgetCosts and budget

Time required for constructionTime required for construction

Purpose and Purpose and Application Recycling Application Recycling

Reduced costReduced cost

Preservation of existing pavement Preservation of existing pavement geometricsgeometrics

Conservation of aggregates and bindersConservation of aggregates and binders

Preservation of the environmentPreservation of the environment

Energy conservationEnergy conservation

DefinitionsDefinitions

Recycled asphalt pavement (RAP)Recycled asphalt pavement (RAP)

Reclaimed aggregate material (RAM)Reclaimed aggregate material (RAM)

Recycled hot-mix asphaltRecycled hot-mix asphalt

Asphalt recycling agentAsphalt recycling agent

Asphalt modifierAsphalt modifier

Types of HMA Types of HMA Pavement RecyclingPavement Recycling

Cold in-place recycling (CIPR)Cold in-place recycling (CIPR)

Hot in-place recycling (HIPR)Hot in-place recycling (HIPR)

Hot central plant recycling (HCPR)Hot central plant recycling (HCPR)

Cold In-Place Cold In-Place Recycling (CIPR)Recycling (CIPR)

Used by cities, counties, states and Used by cities, counties, states and countries around the world for countries around the world for rehabilitationrehabilitation

Primarily used on lower volume roadsPrimarily used on lower volume roads

Substantial savings possible compared Substantial savings possible compared to hot recycling or reconstructionto hot recycling or reconstruction

CIPRCIPRPurpose and Purpose and ApplicationApplication

Correcting asphalt pavement distress Correcting asphalt pavement distress No heatNo heat In-placeIn-place Combined withCombined with

Stabilizing agentStabilizing agent Recycling agentRecycling agent AggregateAggregate

CIPRCIPREquipment TrainEquipment Train

Hot In-place Hot In-place Recycling (HIPR) Recycling (HIPR)

Soften top 50 mm (2 in) of existing Soften top 50 mm (2 in) of existing asphalt pavement with heatasphalt pavement with heat

Mechanically removing the pavementMechanically removing the pavement

Mixing with asphalt binder and/or new Mixing with asphalt binder and/or new mixturemixture

Replacing recycled pavement on Replacing recycled pavement on surfacesurface

HIPRHIPRPurpose and Purpose and ApplicationApplication

Corrects HMA surface distressCorrects HMA surface distress

RuttingRutting

CrackingCracking

RavelingRaveling

BleedingBleeding

RoughnessRoughness

HIPR – ConstructionHIPR – ConstructionMethods and Methods and EquipmentEquipment

Heater scarificationHeater scarification

RepavingRepaving

RemixingRemixing

HIPR - What Are HIPR - What Are Potential Problems Potential Problems Here?Here?

HIPR HIPR Equipment Equipment Development Early Development Early LimitationsLimitations In-place air voidsIn-place air voids

OverheatingOverheating Air qualityAir quality SafetySafety DepthDepth Production / costProduction / cost VegetationVegetation

HIPR - Needs Identified HIPR - Needs Identified To Further To Further Implementation Implementation

Higher mixture temperaturesHigher mixture temperatures

Greater depthsGreater depths

Improved air qualityImproved air quality

Variable widthsVariable widths

Reduced noiseReduced noise

HIPR - Needs Identified HIPR - Needs Identified to Further to Further ImplementationImplementation

Larger amounts of new materialLarger amounts of new material

Climb steep gradesClimb steep grades

Better uniformityBetter uniformity

QC/QA guidelinesQC/QA guidelines

HIPRHIPRPerformancePerformance

Improved penetration of asphalt cementImproved penetration of asphalt cement

Improved rideImproved ride

Edge, transverse, and midlane cracking Edge, transverse, and midlane cracking no improvementno improvement

HIPRHIPRLimitationsLimitations

Structurally sound existing pavementStructurally sound existing pavement

HIR limited to 50 mm (2 in) depthHIR limited to 50 mm (2 in) depth

Prefer dry and warm weatherPrefer dry and warm weather

Manholes and utility vaultsManholes and utility vaults

Surface treatmentsSurface treatments

Air qualityAir quality

Economics may constrain on short Economics may constrain on short sectionssections

Hot Central Plant Hot Central Plant Recycling (HCPR)Recycling (HCPR)

RAP useRAP use Tens of millions of tons usedTens of millions of tons used Everyday occurrenceEveryday occurrence Over 40 million tons generated/yearOver 40 million tons generated/year 80 percent of all HMA removed is 80 percent of all HMA removed is

recycled into HMArecycled into HMA Severe limitations in some areasSevere limitations in some areas

HCPR – Construction HCPR – Construction Methods and Methods and EquipmentEquipment

Construction sequenceConstruction sequence

Pavement removalPavement removal

Crushing and stockpilingCrushing and stockpiling

Mixing in central plantMixing in central plant

Laydown and compactionsLaydown and compactions

HCPRHCPRGenerating RAPGenerating RAP

HCPRHCPRMilled RAPMilled RAP

Little additional processing requiredLittle additional processing required

Uniform properties in layerUniform properties in layer

GradationGradation

Asphalt contentAsphalt content

Asphalt propertiesAsphalt properties

Usually stored in separate stockpileUsually stored in separate stockpile

HCPRHCPRRAP PerformanceRAP Performance

FHWA survey of 17 statesFHWA survey of 17 states RAP mixes comparable to virgin mixesRAP mixes comparable to virgin mixes

Proper designProper design Process controlProcess control

Louisiana studyLouisiana study No significant differences in RAP mix No significant differences in RAP mix

and controland control

HCPRHCPRQuality Control Quality Control

Similar tests used for virgin asphalt Similar tests used for virgin asphalt cementcement

Additional tests requiredAdditional tests required

More frequent testingMore frequent testing

Greater variation in test resultsGreater variation in test results

HCPR - Recycled Mix HCPR - Recycled Mix Design & Design & PerformancePerformance

UniformityUniformity

Depth of HMADepth of HMA

Presence of chip Presence of chip sealsseals

Asphalt content Asphalt content (bleeding)(bleeding)

Aggregate Aggregate gradationgradation

Asphalt propertiesAsphalt properties

TrafficTraffic

Types of Types of pavement pavement distressdistress

HCPRHCPRSuperpave and Superpave and RecyclingRecycling

Research completed NCHRP 9-12Research completed NCHRP 9-12

Table 2 - MP2Table 2 - MP2 RAP Percentage Recovered RAP Grade

Recommended Virgin Asphalt Binder Grade

PG xx-22 or lower

PG xx-16

PG xx-10 or

higher No change in binder selection <20% <15% <10% Select virgin binder one grade softer than normal (i.e., select a PG 58-28 if a PG 64-22 would normally be used)

20 – 30% 15 – 25% 10 – 15%

Follow recommendations from blending charts

>30% >25% >15%

HCPRHCPRLimitationsLimitations

Stockpile variabilityStockpile variability

Gaseous emissionsGaseous emissions

Surface treatments and rubberized Surface treatments and rubberized materialsmaterials

Structural evaluation of recycled Structural evaluation of recycled materialsmaterials

Reconstruction Reconstruction IssuesIssues

Condition of subgradeCondition of subgrade

Traffic controlTraffic control

UtilitiesUtilities

GeometricsGeometrics

SafetySafety

Project budgetProject budget

ReviewReview

What are some rehabilitation options What are some rehabilitation options when a pavement is near the end of its when a pavement is near the end of its service life?service life?

What are the major issues concerned What are the major issues concerned with reconstruction?with reconstruction?

Key ReferencesKey References

Davis, B. 2000. “Survey Shows Public Ignorant of Davis, B. 2000. “Survey Shows Public Ignorant of Industry Progress – Asphalt Pavement Recycling Industry Progress – Asphalt Pavement Recycling Leader.” Leader.” California Asphalt California Asphalt May/June 2000, Asphalt May/June 2000, Asphalt Pavement Association, Laguna Hills, CAPavement Association, Laguna Hills, CA

Federal Highway Administration. 2000. “Reclaimed Federal Highway Administration. 2000. “Reclaimed Asphalt Pavement - User Guideline - Asphalt Asphalt Pavement - User Guideline - Asphalt Concrete (Hot Recycling). Federal Highway Concrete (Hot Recycling). Federal Highway Administration, Washington, DC. Administration, Washington, DC. http://www.tfhrc.gov/hnr20/recycle/waste/rap132.htmhttp://www.tfhrc.gov/hnr20/recycle/waste/rap132.htm

Key ReferencesKey References

Kandahl, P. S. and R. B. Mallick. 1997. Kandahl, P. S. and R. B. Mallick. 1997. Pavement Recycling Guidelines for State and Pavement Recycling Guidelines for State and Local Governments – Participant’s Reference Local Governments – Participant’s Reference Book.Book. FHWA-SA-97. Available on CD dated FHWA-SA-97. Available on CD dated March 1998. Federal Highway March 1998. Federal Highway Administration, Washington, DC.Administration, Washington, DC.

Key ReferencesKey References

McDaniel, R., and R. M. Anderson. 2000a. McDaniel, R., and R. M. Anderson. 2000a. Recommended Use of Reclaimed Asphalt Recommended Use of Reclaimed Asphalt Pavement In Superpave Mix Design Method: Pavement In Superpave Mix Design Method: Guidelines. Guidelines. NCHRP Project 9-12. NCHRP NCHRP Project 9-12. NCHRP Research Results Digest Number 253. Research Results Digest Number 253. National Cooperative Highway Research National Cooperative Highway Research Program, Transportation Research Board, Program, Transportation Research Board, Washington, DC.Washington, DC.

Key ReferencesKey References

McDaniel, R., and R. M. Anderson. 2000b. McDaniel, R., and R. M. Anderson. 2000b. Recommended Use of RAP in Superpave Mix Recommended Use of RAP in Superpave Mix Design: Technician’s Manual.Design: Technician’s Manual. NCHRP NCHRP Project 9-12. NCHRP Report 452. National Project 9-12. NCHRP Report 452. National Cooperative Highway Research Program, Cooperative Highway Research Program, Transportation Research Board, Washington, Transportation Research Board, Washington, DC.DC.

Key ReferencesKey References

CMI Communications. 2000. “The CMI CMI Communications. 2000. “The CMI Triple-Drum Hot Mix Asphalt Plant, The Triple-Drum Hot Mix Asphalt Plant, The Ultimate Counter-Flow Plant Design for Ultimate Counter-Flow Plant Design for Productivity and Environmental Productivity and Environmental Performance.” CMI Corporation, Oklahoma Performance.” CMI Corporation, Oklahoma City, OK. City, OK. http://www.cmicorp.com/frame/prod/denasph.http://www.cmicorp.com/frame/prod/denasph.htmlhtml

Key ReferencesKey References

American Recycling and Reclaiming American Recycling and Reclaiming Association (ARRA). 2000. “ARRA Member Association (ARRA). 2000. “ARRA Member Firms Recycle 34 Million Tons.” Firms Recycle 34 Million Tons.” ARRA ARRA Newsletter Fall 2000. Newsletter Fall 2000. American Recycling American Recycling and Reclaiming Association, Annapolis, MD.and Reclaiming Association, Annapolis, MD.

Key ReferencesKey References

Kazmierowski, T., P. Marks, and S. Lee. 1999. Kazmierowski, T., P. Marks, and S. Lee. 1999. “Ten-Year Performance Review of In Situ Hot-“Ten-Year Performance Review of In Situ Hot-Mix Recycling in Ontario.” Mix Recycling in Ontario.” Transportation Transportation Research Record. Research Record. Transportation Research Transportation Research Board, Washington, DC. Board, Washington, DC.

Button, J. W., C. K. Estakhri, and D. N. Little. Button, J. W., C. K. Estakhri, and D. N. Little. 1999. “Overview of Hot In-Place Recycling of 1999. “Overview of Hot In-Place Recycling of Bituminous Pavements.” Bituminous Pavements.” Transportation Transportation Research Record 1684. Research Record 1684. Transportation Transportation Research Board, Washington, DC.Research Board, Washington, DC.

StandardsStandards

ASTM D4552 – Standard Practice for ASTM D4552 – Standard Practice for Classifying Hot-Mix Recycling Agents.Classifying Hot-Mix Recycling Agents.