Recycled Asphalt Pavement - Purdue University

RECYCLED ASPHALT PAVEMENTSAVING PAVEMENT · SAVING MONEY · SAVING THE ENVIRONMENTDudley Bonte, Rieth-RileyBecky McDaniel, North Central Superpave CenterIndiana LTAP Asphalt WorkshopNovember 12, 20091

TODAY’S TOPICS What:RAP and its History Where: Uses of RAP When: Limitations to Use How: RAP Processing, Equipment, QC,Best Practices How: Current INDOT Specs, Other Specsand Potential Changes in Specs Why use RAP?2

WHAT IS RAP? ReclaimedAsphalt Pavement (RAP) Existing pavements removed and reused Produced by Milling -- Upper pavement layers removed andreplaced with new pavementFull-Depth Removal -- Pavement completelyremoved and reprocessed3

TYPICAL ASPHALT MIX 95%aggregate (approx. 30% of cost) 5% asphalt binder (approx. 70% of cost)Reusing: Reduces need to quarry more aggregate Reduces energy/costs to produce, process,transport aggregate Reduces asphalt demand4

HISTORY OF RAP USE Firstused in 1915 (!) Major emphasis started in 1970’s Oil embargo and increased oil pricesImproved milling machinesCounterflow drum plants Became routine in many statesNecessary to be competitive (lower bid prices)5

USES OF RAP RAP can be used forBaseFillShouldersAlleys But,the highest and best use of RAP is back intonew asphalt mixtures. Most beneficialMost cost effective6

PERCENT RECYCLED - 1993100808064606056374031200Asphalt SteelCansNews Plastic Glass

ALONG CAME SUPERPAVE No guidelines for using RAPNew system – lots of unknownsInterim guidance based on old Marshall mixes––– Up to 15% RAP, no change16-25% RAP, drop binder grade one incrementOver 25% RAP, blending chart neededNational research confirmed those levels in 20018

CURRENT USAGE Moststates are back to or above preSuperpave usage levels. Nationwide only a few states do not allow RAP.AASHTO specs allow easy use of up to 25%. Contractorsin most states reported using RAPwhenever they can. Lower bid prices. Performanceas good as virgin mixes.9

TODAY Strong incentives to increase RAP use––– Increased material and energy costs Binder costs rose over 300% in 2007 & 2008Material supply issuesGrowing environmental concernsGrowing demand–––Use RAP in more mixes (i.e. surfaces)Use higher RAP quantitiesIncreased Availability of RAP from projects10

WHERE CAN RAP BE USED? Virtually Base and intermediatePotential to use higher amounts Surface any mix – following best practicesmixesTendency to allow lower amountsFriction and cracking are potential concernsIncreased resistance to rutting11

AGENCY CONCERNS(LIMITATIONS) QualityConcerns (including friction) Consistency of RAP Ability to Meet Volumetric Requirements Durability of Mixes Stiffness of Binder Use with Polymers12

WHAT CONTRACTORS CAN DO TO OPTIMIZE RAP13

OBTAINING & PROCESSINGRAP14

COMPOSITE SOURCES (GOK) Usually chunks and slabs from full depth pavement removal Plant cleanout Reject material or excess returned from jobs Excavation Other sources15

In GOK PileAfterProcessing16

Composite RAP is reprocessed (i.e.crushed, screened, stockpiled andQC tested)17

The reprocessedproducts are veryconsistentcomponents18

RAP FROM MILLING Removesold/distressedpavement Improves smoothness Eliminates costlyshoulder work Maintains drainagefeatures, curbs,clearance Valuable rehab option19

Millings generally require no additional processing. After testing they may be incorporated into HMAmixtures Millings are stockpiled separately by job and size20

FRACTIONATING TO -1/4”21

COST/BENEFITS OF RAP Milling or Pavement Salvage CostsMill, haul & stockpile: 6.50/ tonExcavate, haul & stockpile: 7.00/tonReprocessing: 5.00/ton VirginMaterial Costs Coarse Aggregate 12.00/t Fine Aggregate 8.00 PG Binder 450.0022

COST SAVINGS USING RAPFOR A TYPICAL 19.0MM INTERMEDIATE% RAPNotes015Per ton Savings (materials only)0 3.4025 5.5040 6.80Does not includepremium PG58-28Includes premiumPG58-2825% RAP in an intermediate 19.0mm HMA will saveapproximately 11% per tonAssuming a 3” lay; for every 1 million resurface dollar this willequate to approximately 2.2 lane miles of additional paving.23

COST SAVINGS USING RAPFOR A TYPICAL 9.5MM SURFACE% RAPNotes015Per ton Savings (materials only) 0 3.4025 5.5040 6.80Does not includepremium PG58-28Includes premiumPG58-2825% RAP in a Surface 9.5mm HMA will save approximately 9% perton.Assuming a 1.5” lay; for every 1 million resurface dollars this willequate to approximately 2.6 lane miles of additional paving24

RAP MANAGEMENT & BEST PRACTICES Monitor& control incoming RAP Stockpile job millings by job and size QC tests on all RAP Fractionate RAP (when applicable) Avoid contamination Keep the RAP dry –paved and sloped area,covered stockpile ( BTU’s ) Know Plant limitations (e.g. Batch plant)25

ContaminationNot Good26

RAP IS JUST ANOTHER COMPONENT OF HMA27

SAME STANDARDSAS VIRGIN MIXES INDOTSec. 400StandardSpecifications Aggregatequality Superpavevolumetriclab mix designs QC/QAverificationtesting and acceptance28

RAPShingles29

CURRENT INDOT SPECS Upto 25.0% RAP by weight of total mixture Upto 15.0% RAP in surface courses for 3million ESALs or higher or for open gradedmixtures Nochange in binder grade up to 15.0% RAP;drop one grade for greater than 15.0% RAP30

POTENTIAL CHANGE IN INDOT SPECS Current research and testing suggestshigher RAP contents may be feasible–– RAP blending studyRAP friction studyINDOT – industry meeting tomorrowPotential to allow up to 25% RAP without agrade change and up to 40% with changeWatch for final decision and supplementalspecs31

REMOVING/LOWERING BARRIERS Nationwidespecs vary widely Several states allow up to 50% RAP Workis on-going to encourage all states toallow RAP use Research is continuing to explore higherRAP contents Potential for WMA plus RAP32

HMA RECYCLING ETG FHWAinitiated in May 2007 Managed by NCAT Purpose – Coordinate, develop nationalguidance and recommendations on RAP use Goal – encourage all states to allow 15-20%RAP, then increase some to 25-30% Demo projects, document performance, shareinfo, best practices, research33

HIGHER RAP CONTENTSwork – do perform – if properly designed,produced and constructed Do But,need attention to detail Some precautions are neededMany of these are the same as for aggregate bestpractices34

CONCLUSIONS RAPhas long history of successful use. Asphalt recycling is sustainable. Asphalt recycling is economical. Asphalt recycling works!35

THANKS TO: LTAPand APAI NAPA, AASHTO, FHWA, APAI sponsoredworkshop, Materials and EnergyConservation in Hot Mix Asphalt Available on NAPA website Gerry AndHuberto you!36

RECYCLED ASPHALT PAVEMENT SAVING PAVEMENT · SAVING MONEY · SAVING THE ENVIRONMENT Dudley Bonte, Rieth-Riley Becky McDaniel, North Central Superpave