Sustaining our Highwayspetersenasphaltconference.org/download/2008/1-1--Copeland.pdf · Sustaining our Highways: ... Practices for Recycled Asphalt Pavements Audrey Copeland ... –

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U.S. Department of TransportationFederal Highway Administration

Sustaining our Highways:Sustaining our Highways:A National Perspective on RAP Usage & Best A National Perspective on RAP Usage & Best

Practices for Recycled Asphalt PavementsPractices for Recycled Asphalt Pavements

Audrey CopelandAsphalt Pavement Engineer

Pavement Performance Prediction Symposium July 16, 2008Laramie, WY

2U.S. Department of TransportationFederal Highway Administration

Presentation OutlinePresentation Outline

• What is RAP?– Hasn’t it been used

for years?– Economic drivers

• State-of-the practice– State DOTs– Contractors– Major concerns and

barriers

• National perspective– Objectives and

essential steps for increasing pavement recycling

– FHWA involvement and activities

• Constructability– Best practices


What is RAP?What is RAP?

• Reclaimed Asphalt Pavement

• Removed and/or reprocessed pavement materials containing: ~ binder (5%)~ aggregates (95%)


Reclaimed Asphalt Pavement (RAP)Reclaimed Asphalt Pavement (RAP)

Sources of RAP– Milling– Pavement removal– Plant waste

Most Common Uses– Addition to HMA– Aggregate in cold-mix– Granular base– Fill or embankment

material


HasnHasn’’t RAP been used for years?t RAP been used for years?

1970s – Begins a recycling boom

1980s – 1990s – Technical Guidance• NCHRP• FHWA



1990s – Superpave developed• New mix design system• New gradation controls• State DOTs limit RAP allowed



• NCHRP Project 9-12 Recommended Use of RAP in Superpave

• Contractors implement improved techniques– RAP processing – Gradation control

2000s – Superpave Implemented

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Economic Drivers for Using RAPEconomic Drivers for Using RAP

Growth in recycling occurs when it is economical to do so.


Change in Producer Prices Change in Producer Prices for Construction Segments for Construction Segments

100

110

120

130

140

150

160

170

12/03 12/04 12/05 12/06 12/07

Highway and street construction: 66%Other heavy construction: 54%Nonresidential buildings: 37%Single-unit residential: 27%Consumer price index: 18%

Source: BLS (CPI, PPI)


Change in Producer Price Change in Producer Price Indexes (PPI) for Highway InputsIndexes (PPI) for Highway Inputs

100

150

200

250

300

350

400

450

12/03 12/04 12/05 12/06 12/07

#2 diesel fuel: 306%

Asphalt Paving Mixtures & Blocks: 70%

Concrete products: 36%

Consumer price index (CPI-U): 18%

Source: BLS (CPI, PPI)


Asphalt Production Cost CategoriesAsphalt Production Cost Categories

0

10

20

30

40

50

60

70

80

90

100

Material Plant Production Trucking Lay Down

Perc

ent (

%) o

f Cos

t

Greatest Potential for Cost Savings isin the Materials Category


Material Costs and Savings with RAPMaterial Costs and Savings with RAP

$64.20Total Virgin Materials

$8RAP (including milling, transportation, & processing)*

$30 (94%)Rock$600 (6%)Liquid Asphalt Cement

Cost ($) per ton (%mix)Material

* Brock, J.D. and Scott Thompson. “Plant Processing Strategies to Maximize RAP Use”. Presented at HMA Energy & Recycling Symposium, Austin, TX, October 22-23, 2007.


0

10

20

30

40

50

60

70

0% 10% 20% 30% 40% 50% 60%

Percentage of RAP

Dol

lars

($) p

er to

n

Savings with RAPSavings with RAP

$5.62

$8.43$16.86

$28.10

$64.20Total Virgin Materials

$8RAP (including milling, transportation, & processing)*

$30 (94%)Rock

$600 (6%)Liquid Asphalt Cement

Cost ($) per ton (%mix)Material


Why allow high RAP?Why allow high RAP?• Reduced costs

• For example…– Upfront cost impact - If specification allows high RAP,

contractors may submit different bid prices on plant mix items or frequency of price adjustments and delays.

– Future cost impact – higher RAP pavement has different life-cycle properties

• The cost effectiveness of higher-RAP mixes depends on:– Unit costs of mixtures– Performance during and after placement

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RAP StateRAP State--ofof--thethe--PracticePractice

The Current Status of Pavement Recycling with RAP


The The ““StateState--ofof--RecyclingRecycling””

• Survey conducted between June 2007 to March 2008 by Cecil Jones, NCDOT

• Questions posed:– How much RAP is allowed in mixtures?– How much RAP is actually used?– What are the main roadblocks to greater usage of

RAP?

• Responses from all 50 states and Ontario


Average Amount of RAP Average Amount of RAP -- BaseBase

Permitted by Specifications

0%1 - 10%10 - 20%20 - 30%≥30%n/a

Used

0%10%15%20%25%≥30%n/a

Jones, Cecil. “Review of DOT RAP survey.” Presented to the RAP ETG Meeting, San Diego, CA, March 2008.


Average Amount of RAP Average Amount of RAP -- IntermediateIntermediate

0%10%15%20%25%≥30%n/a

0%1 - 10%10 - 20%20 - 30%≥30%n/a



Used


Average Amount of RAP Average Amount of RAP -- SurfaceSurface

0%10%15%20%25%≥30%n/a

0%1 - 10%10 - 20%20 - 30%≥30%n/a



Used


Amount of RAP Amount of RAP PermittedPermitted (by layer)(by layer)

0 5 10 15 20 25

0

10

15

20

25

≥ 30

n/a

% R

AP

Spec

ified

Number of States

Surface layerIntermediate layerBase layer


Amount of RAP Amount of RAP UsedUsed (by layer)(by layer)

0 5 10 15 20 25 30 35

0

1-10

10-19

20-29

≥ 30

n/a%

RA

P U

sed

Number of States

Surface layerIntermediate layerBase layer


State Survey Results SummaryState Survey Results Summary

• Majority of States use between 10 & 20 % RAP in all layers – average ~ 12%.

• Two States (NV & AZ) do not allow RAP and one State does not use RAP (ND).

• Four additional States do not allow RAP in surface mixtures– RI, FL, OK, NM


Leaders in highLeaders in high--RAP Usage (RAP Usage (≥≥30%*)30%*)

• Base– Montana– South Dakota– Michigan– Ohio– California– Massachusetts– Nebraska

• Surface (20 to 30 %)– Minnesota– Oregon

• Intermediate– Montana– South Dakota– Michigan– Ohio

*Note “by percentage”


Major Concerns/BarriersMajor Concerns/Barriers

• Consistency/Quality of final mixture properties

• Uniformity of RAP material• Selecting binder grade

– Adequate and uniformly blended total asphalt binder

• Proper mix design procedures• Pavement performance

– Cracking– Durability

FHWA Division Office Survey 2007


Other major barriersOther major barriers

• Aged binder • Method to measure

asphalt content in RAP• Moisture• Enforcement of

specifications• Restrict RAP when PMA

is used?• Dust-to-binder

requirements• Ninitial requirements

• Premature distress in surface course

• Fatigue• Handling mixture

problems on RAP projects

• Lack of knowledge by end users

FHWA Division Office Survey 2007


Contractor SurveyContractor Survey

Surface Binder Base Shoulder Polymer-modified SMA

Average Used

Average Allowed by SpecificationsAverage Potential

26

3336 36

20

11

18

2327

26

12

3

12

1821

20

6

1

0

5

10

15

20

25

30

35

40

Perc

ent (

%) R

AP

Pavement Layer or Type

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FHWA Involvement and ActivitiesFHWA Involvement and Activities

A National Perspective


Our ObjectivesOur Objectives

• Encourage the use of recycled materials in the construction of highways to the maximum economical and practical extent possible with equal or improved performance.

• Greatest impact in pavement recycling can be realized through the promotion of Reclaimed Asphalt Pavement (RAP).


WhatWhat’’s Needed?s Needed?

1. Clear engineering and environmental standards and policy for the use of RAP.

2. Funded, coordinated research to support standards.

3. Public and industry working groups.4. Education.


FHWA Recycled Materials PolicyFHWA Recycled Materials Policy

• FHWA recognizes need to increase the highway industry’s overall use of recycled materials

• Engineering, Economic, and Environmental benefits

• First consideration in materials selection

• Initial review of engineering and environmental suitability

• Assessment of economic benefits should follow selection process

• Remove restrictions with no technical base


Guidance DocumentsGuidance Documents

www.fhwa.dot.govwww.fhwa.dot.gov/pavement/recycling/rap/pavement/recycling/rap


Nationally Funded ResearchNationally Funded Research

• NCHRP Project 9-46– Mix Design and Evaluation Procedure

for High Reclaimed Asphalt Pavement Content in Hot Mix Asphalt

• Asphalt Research Consortium (ARC)– FHWA Cooperative Agreement


RAP Expert Task Group (ETG)RAP Expert Task Group (ETG)

• FHWA Sponsored

• Membership– State DOT– AASHTO– NCAT– NAPA– Hot Mix Asphalt Industry– North Central

Superpave Center– Academia

• Chairman– Gerry Huber, Heritage

Research Group

• Secretary– Andrea Kvaznak, NCAT


RAP ETG ActivitiesRAP ETG Activities

• Purpose – Advance the use of RAP in asphalt paving applications by providing highway agencies with critical information regarding the use of RAP, technical guidance on high-RAP projects, and direction on research activities.

• Showcase Performance - Field Projects • State of Practice and Best Practices • Proposed Standard Practice for Use of RAP


Field Project GoalsField Project Goals

• Documentation• Mix design process, production, and

construction• Performance testing• Develop information for future mix design

and quality control procedures

• Evaluate potential impact on performance


Data CollectionData Collection

1) Project Summary

2) Material Properties

3) Production Information

4) LaydownInformation

5) Testing


Field Projects to DateField Projects to Date

December 200745%Florida

May 200830 – 40 %Kansas

Summer 200830%Delaware

November 200725%Wisconsin

October 200730% and 50%South Carolina

September 200740%North Carolina

DateRAP PercentageState


Best Practices LearnedBest Practices Learned

• Separate/blended stockpiles• Fractionation• Sample RAP sources

regularly• Plant processing• Warm-mix technologies may facilitate high

RAP • Avoid production of mixtures at various

temperatures - warm mix versus hot mix

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ConstructabilityConstructability

“Farming looks mighty easy when your plow is a pencil and you’re a thousand miles from

the corn field”– Dwight Eisenhower

September 11, 1956


Constructability ObjectivesConstructability Objectives

• Quality

• Efficiency

• Productivity

• Cost effectiveness


Using RAP and ConstructabilityUsing RAP and Constructability

The question we’re posing…• How much RAP can we include in the

mix and meet specification and constructability requirements?

• Biggest impact can be made in processing and production.


Getting the RAP readyGetting the RAP ready……

• Unprocessed RAP– Not subject to QC– Visual Inspection

• Processing RAP– Uniform size– Promotes final blend

consistency


• Stockpiling– Conical– Well-maintained– Sample frequently

• Comprehensive QC testing– Absorption– Moisture content– Asphalt content– Gradation

Maintaining RAP QualityMaintaining RAP Quality


• Loader operator

• RAP feed system– Scalping screen

Efficient OperationsEfficient Operations


At the PlantAt the Plant• Superheating of

aggregate• Air flow• Baghouse• Warm mix


Insuring QualityInsuring Quality

• Final mixture– Volumetric properties– Extraction– Gradation– Asphalt content– High-RAP

• PG grade of blended binder• Quality of Aggregate

• Performance Testing


LaydownLaydown and Compactionand Compaction

– No special requirement/techniques

• May require more attention than conventional mixes

– Mix Workability - Stiffer• Density• Heat mixture, more roller

passes, heavier roller?

– Cooler temperatures• Reduced compaction times• Warm mix technologies can

extend compaction times


SummarySummary

• Asphalt Pavement Recycling– Greatest single upfront cost saving measure

available to highway agencies is increasing the use of RAP in the construction and rehabilitation of asphalt pavements.

– The FHWA encourages the increased use of RAP.

• The majority of State DOTs use between 10 and 20% RAP.

• Contractors can effectively use RAP often and in high amounts with processing and production best practices.

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Thank you! Questions?

www.fhwa.dot.govwww.fhwa.dot.gov/pavement/recycling/rap/pavement/recycling/rap