08fall_sustainmgtpracs_jimhuddleston

8/19/2019 08Fall_SustainMgtPracs_JimHuddleston

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Sustainable PavementManagement practices

NWPMA FALL CONFERENCEJim Huddleston, P.E.

Executive Director

Asphalt Pavement Association of

Oregon


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Asphalt Sustainability Asphalt Sustainability

Perpetual Pavements

Porous Pavements

Recycle

Warm MixMill and Fill

Thinner Lifts


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Perpetual Pavements

Perpetual Pavement

› Structure Lasts “forever”

» Bottom-Up Design and Construction

» Indefinite Fatigue Life

› Renewable Pavement Surface.

» High Rutting Resistance

» Tailored for Specific Application

› Consistent, Smooth and Safe Driving Surface.

› Environmentally Friendly

› Avoids Costly Reconstruction


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Perpetual Pavements

Max Tensile Strain

Pa v em e n t Fo u n d a t i o n

High ModulusRut Resistant Material (Varies As Needed)

Flexible Fatigue ResistantMaterial 3 - 4”

1.5 - 3” SMA, OGFC or Superpave

}2” to4”

ZoneOf High

Compression


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Perpetual Pavements

Performance Goals - Avoid These

RepeatedBending

Leads toFatigue Cracking

RepeatedDeformation

Leads toRutting

HMA

BaseBase

Subgrade


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Perpetual Pavements

High Strain = Short LifeHigh Strain = Short Life

Low Strain = UnlimitedLow Strain = UnlimitedLifeLife

StrainStrain

Fatigue Theory for Thick PavementsFatigue Theory for Thick Pavements

UnlimitedUnlimitedFatigueFatigue

LifeLife

Fatigue LifeFatigue Life

S t r a

i n

S t r a

i n

100100

MICROSTRAINSMICROSTRAINS


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ExampleExample

Material Cost for each ~ 2.0Material Cost for each ~ 2.0 – – 2.15 ft2.15 ft22

540,000540,000100,000100,000 ++~ 2.5~ 2.555”” Asphalt Asphalt

66”” AB AB

245,000245,000100,000100,000 ++~ 2.5~ 2.544”” Asphalt Asphalt

99”” AB AB

110,000110,000100,000100,000 ++~ 2.5~ 2.533”” Asphalt Asphalt

1212”” AB AB

MechanisticMechanistic

Fatigue LifeFatigue Life

AASHTO AASHTO

ESALESAL’’ss

AASHTO AASHTO

Structural Number Structural Number SectionSection


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Perpetual Pavements


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Pringle Creek CommunityPringle Creek Community – – PorousPorous Asphalt Streets Asphalt Streets

PerformancePerformancein wet weatherin wet weatherhas beenhas beenoutstandingoutstanding


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Common Recycled Materials inCommon Recycled Materials in

Asphalt Pavements Asphalt Pavements

Shingles

RAP

Crumb / Tire Rubber

GlassSlag

All are in different stages of utilization /evaluation

recycled pavementrecycled pavement


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Raise the Roof with ShinglesRaise the Roof with ShinglesRoofing shinglesRoofing shingles

comprised of:comprised of: – – Polymer modified asphaltPolymer modified asphalt

– – Fiberglass or felt fibersFiberglass or felt fibers

– – GritGrit – – angular fineangular fineaggregateaggregate

– – Mineral filler Mineral filler


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ExampleExampleRoofing shingles contain ~ 20% asphaltRoofing shingles contain ~ 20% asphalt

Use 5% shingles in HMA, reduce 1%Use 5% shingles in HMA, reduce 1%asphaltasphalt

Reduce 0.1 ton AC/ton HMAReduce 0.1 ton AC/ton HMAReduce cost by $5.00/ton HMAReduce cost by $5.00/ton HMA


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Issues with ShinglesIssues with ShinglesTear Tear --off shingles require more processingoff shingles require more processing

than manufacturing waste.than manufacturing waste.Tear Tear --offs have aged asphaltoffs have aged asphalt – – may requiremay require

adjustments.adjustments.Be careful using tear Be careful using tear --offs and RAP inoffs and RAP insame mix.same mix.

Sizing of shingle particles is importantSizing of shingle particles is important – – should be minusshould be minus ½½ inch.inch.


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Not What WeNot What We’’re Looking For!re Looking For!


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Reclaimed Asphalt PavementReclaimed Asphalt Pavement ““ RAPRAP””

Removed and/or reprocessed pavement

materials containing asphalt and aggregates

Over 80 percent of the asphalt pavement,

removed each year for widening and

resurfacing, is re-usedRepresents close to 100 mill ion tons / year

RAP is the Nation’s No. 1 recycled material inboth total amount and percentage recycled



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Benefits of usingBenefits of using ““ RAPRAP””

Sustainable-reduces demand for new

materials

Saves energy

Reduces carbon outputImproves performance

Saves money



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RAP: sustainable & carbon neutral RAP: sustainable & carbon neutral


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RAP: sustainable & carbon neutral RAP: sustainable & carbon neutral

The entire annual CO2 / greenhouse gas emissions /

carbon footprint from a typical hot-mix plant (~ 2,500 tons)could be totally offset by using 20 - 25% RAP in pavement

mix designs -- accomplished by minimizing acquisition of

energy intensive (natural) raw materials such as aggregate

and petroleum asphalt.


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RAP: Save money RAP: Save money

30,000 tons of RAP contains 1,800 tons of asphalt worth

$1,000,000 and aggregate worth over $300,000. If acontractor gives a 50% “ credit” in their bid the

owner/agency will save $6-7 per ton of mix over the price

of 100% virgin mix


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RAP Standard of PracticeRAP Standard of PracticeODOT allows 30% in all Level 2 and 3ODOT allows 30% in all Level 2 and 3

mixesmixesLocal agencies should not establish moreLocal agencies should not establish morerestrictive RAP practicerestrictive RAP practice

ODOT working on specs to allow higherODOT working on specs to allow higherRAP contentRAP content

May require softer binder grade, separatedMay require softer binder grade, separatedsizessizes


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RAP PerformanceRAP PerformanceMany studies show RAP mixes improveMany studies show RAP mixes improve

Rut resistanceRut resistanceSome studies show slight increase inSome studies show slight increase incrackingcracking

When softer binder used crack resistanceWhen softer binder used crack resistanceis found to be equal to or better than newis found to be equal to or better than newmixmix

RAP mixes generally improve resistanceRAP mixes generally improve resistanceto moisture damageto moisture damage


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Maximizing RAP contentMaximizing RAP contentSignificant successful experience at 40Significant successful experience at 40--

50% RAP content50% RAP contentBarriers include technical productionBarriers include technical productionissues, RAP availability, agencyissues, RAP availability, agencyacceptance, control technologyacceptance, control technology

May require softer binder grade, separatedMay require softer binder grade, separated

sizessizesWarm mixWarm mix


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SUPERPAVE MIX WITH 1/2 RAP

White Rock4-0

AA%

White Rock3/8 - 4

C%

X%

White Rock1/2 - 3/8

B%

RAP1/2 - 0

A%


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sizing RAP sizing RAP


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PROCESSED RAP SCREENED TO ORIGINAL INGREDIENTS

RAPBlack Rock

1-0

AA%

Black Rock

1/2 - 3/8

DD%

Black Rock3/8 - 4

CC%

Black Rock4 - 0

BB%


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sizing RAP sizing RAP


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Benefits of Separated SizesBenefits of Separated SizesIncreased controlIncreased control

Can use in more mix types including openCan use in more mix types including opengradedgraded

Allows higher RAP content Allows higher RAP content


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Warm Mix Asphalt ( Warm Mix Asphalt ( “ “ WMAWMA” ”


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Hot Mix Asphalt 275-325oF

Cold Mix Asphalt 60oF

Warm Mix Asphalt 250-275oF

What is Warm Mix Asphalt?


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Advantages of Lower

Temperatures

• Lower fumes and emissions• Lower energy consumption

• Lower plant wear • Decreased binder aging

• Early site opening• Cool weather paving

• Compaction aid for stiff mixes


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warm mix asphalt warm mix asphalt

Many different technologies

Additives such as waxes and zeolites

Emulsions and water foaming processes

Costs differ; some higher, some lower

End-result: to lower mix temperatures

from 300 oF

~ 250 oF (or lower)Less energy demand / fuel consumption

lower emissions: plant and field

Quantifying energy and emissions

~ 15% less fuel consumption

~ 20% less CO2 emissions

Lower NOx, particulate, other emissions

States, Producers, Contractors, FHWA all interestedTRB funding @ ~ $2MM; performance/ emissions


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– Light oils are either put in asphalt orleft in asphalt during refining

– These light oils boil at above 285o

F

– By mixing at below 285oF, the boiling

point is never reached…eliminatingsmoke (vapor) and corresponding

smell

No Smoke – No Smell…Why?


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Warm Mix in OregonWarm Mix in OregonKnife RiverKnife River – – Medford first plantMedford first plant

Uses foaming technologyUses foaming technologyTest sections for City of MedfordTest sections for City of Medford

Technology is well developedTechnology is well developed

Lower temperature by 25Lower temperature by 25--3030’’

Improve/extend workability andImprove/extend workability and

compactioncompaction Allow higher RAP percentage Allow higher RAP percentage


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WARM MIX Foaming systemWARM MIX Foaming system


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– To achieve compaction (density)…run 275oF

and foam virgin liquid – By using a standard liquid 64-22, you

produce a much softer product than with

virgin mix due to:

• Lower temperature results in lessoxidation

• Light oil remains in liquid

• Steam produced from drying the RAP

creates an inert atmosphere

High Percentage Recycle Mix withStandard Grade of Asphalt


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Benefits of High RAP &

Warm Mix


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• Improved Workability

•

No Smoke – No Smell• High Percentage

Recycle Mix withStandard Grade of

Asphalt• 14% Less Fuel

• 14% HigherProduction

• Reduces Cost

For theProducer/Contractor


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• Comfort & Safety

For the Worker


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• Comfort & Safety ofworkers

• Improve Mixes

For the DOT/Public


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– Less oxidation of mix

– More uniformity of compaction

– With fractionating RAP…more uniform

Why will we have aLonger Life Pavement?


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VIRGIN AGGREGATE

HARDER LIQUIDTRANSFERRED FROM

RAP PREVENTSSTRIPPING

NEWHOT FOAM AC

HELPS DURABILITY

Longer Life


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• Comfort & Safety of

workers

• Improve mixes

• Sustainability

For the DOT/Public


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– By Milling & Recycling – 100% of the

material can be re-used – Reduce new aggregate requirement by

245,000,000 tons/year…annually(from 15% to 50%)

–

Reduce oil consumption by 80,000,000bbl/year…approximately 7 days of

imported oil

Why Sustainability?


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workers

• Improve mixes

• Sustainability

• Green

For the DOT/Public


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– Use 14% less fuel due to 50oF lower

temperature

– No volatiles

– Use more recycle

It’s Green!


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workers• Improve mixes

• Sustainability

•

Green• Reduce Cost

For the DOT/Public


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Warm Mix in OregonWarm Mix in Oregon Allow use when available with Allow use when available with ““permissivepermissive””

specsspecsEncourage local producers to invest inEncourage local producers to invest inwarm mix technology, consider incentiveswarm mix technology, consider incentives

Warm mix is the future and will becomeWarm mix is the future and will becomestandard practice owing to economic,standard practice owing to economic,

environmental and operational benefitsenvironmental and operational benefits


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Rehab StrategiesRehab StrategiesThin Lift with finer mixesThin Lift with finer mixes

Mill and FillMill and Fill


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Thinner OverlaysThinner OverlaysMany overlays placed to correct functionalMany overlays placed to correct functional

deficiency (smoothness) rather thandeficiency (smoothness) rather thanstructural,structural,

By using smaller aggregate this can beBy using smaller aggregate this can be

done with thinner liftsdone with thinner liftsLift thickness related to aggregate size.Lift thickness related to aggregate size.

Fine aggregate mixes do not rut more thanFine aggregate mixes do not rut more than

coarse aggregate mixes.coarse aggregate mixes. – – NCHRP ReportNCHRP Report539539


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Thinner OverlaysThinner OverlaysThin lift overlays/inlays will provide smoothThin lift overlays/inlays will provide smooth

surface, a seal, and 15 plus years of lifesurface, a seal, and 15 plus years of lifeUse less materialUse less material

Save money and resourcesSave money and resources


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Thin Overlay ExampleThin Overlay ExampleSay NMAS/lift is 4Say NMAS/lift is 4

For 12.5 mm mix ~ 50 mmFor 12.5 mm mix ~ 50 mm

– – AC content 6.0% AC content 6.0%

– – 217 lbs/217 lbs/sysy = $4.88/sy @ $45/ton= $4.88/sy @ $45/ton

For 9.5 mm mix ~ 37.5 mmFor 9.5 mm mix ~ 37.5 mm

– – AC content 6.5% AC content 6.5%

– – 163 lbs/163 lbs/sysy = $3.99/sy @ $49/ton= $3.99/sy @ $49/ton

Thinner overlay = 18% less asphaltThinner overlay = 18% less asphalt

Thinner overlay = $0.89/sy lessThinner overlay = $0.89/sy less


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Rehab StrategiesRehab StrategiesThe most cost effective sustainableThe most cost effective sustainable

approach involves mill and fill forapproach involves mill and fill forpavement rehabpavement rehab

Removes surface distressRemoves surface distress

Prepares surface for overlayPrepares surface for overlay

Maintains gradeMaintains grade

Generates RAP for future useGenerates RAP for future use

Existing roads and streets are a material source


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milling asphalt pavement milling asphalt pavement


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Washington DOT bond studyWashington DOT bond studyGenerally, milling provided a significantly betterbond at the interface between the existingsurface and the new overlay. Curing time had a

minimal effect on the bond strength. The resultsindicated that the absence of tack coat did notsignificantly affect the bond strength at theinterface for the milled sections, whereas it

severely decreased the strength for the non-milled sections. The results also showed thatincreasing the residual rate of tack coat did notsignificantly change the bond strength at the

interface.


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Economics of Mill and FillEconomics of Mill and Fill2 inch mill and fill2 inch mill and fill – – 30% RAP $7.95/SY30% RAP $7.95/SY

11”” level, 2level, 2”” overlayoverlay – – 30% RAP $10.85/SY30% RAP $10.85/SY

Mill and fill is cheaper, better and moreMill and fill is cheaper, better and moresustainable (net gain in RAP for futuresustainable (net gain in RAP for future

use)use)For road with gravel shoulders savings isFor road with gravel shoulders savings isgreater greater

If you add value of extra RAP generatedIf you add value of extra RAP generatedsavings is greater savings is greater


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Sustainable Pavement ManagementSustainable Pavement Management

ASPHALT ASPHALT::thethe environmentally sustainable pavementenvironmentally sustainable pavement

ASPHALT ASPHALT::


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thethe environmentally sustainable pavementenvironmentally sustainable pavementPorous pavements manage stormwater Build all new pavements to manage at the surface(Perpetual)

Asphalt pvmts accept recycled goods / are recycled (RAP)HMA pavements are environmentally preferred

Less energy to construct, low carbon footprint,speed of construction, very low emissions

Warm Mix lowers energy consumption & emissions

Mill and fi ll with high RAP content is most sustainableapproach to providing high quality pavement

RAP can offset the entire annual HMA GHG emissions

greening the blacktop greening the blacktop


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BEES: econ. &BEES: econ. & env env . impacts . impacts


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BEES BEES


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BEES BEES

White Rock4-0

White Rock3/8 - 4

White Rock1/2 - 3/8

Black Rock3/8 - 4

Black Rock4-0


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SUPERPAVE MIX WITH PROCESSED RAP - CHOICE #1

Black Rock1/2 - 3/8

B%C%

BB%

X%

Black Rock4-0

Black Rock3/8 - 4

White Rock4-0

White Rock3/8 - 4

White Rock1/2 - 3/8


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Black Rock1/2 - 3/8

SUPERPAVE MIX WITH PROCESSED RAP - CHOICE #2

BB%

DD%

CC%

B%

C%

X%

08fall_sustainmgtpracs_jimhuddleston

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