Kendra A. Morrison, U.S. EPA Region 8

Analysis of Recycling Asphalt Shingles in Pavement Mixes from a Life Cycle Perspective

WHY WAS THE STUDY CONDUCTED?

• Support the Colorado Roofs to Roads Initiative: http://www.roofs2roadscolorado.org/

• Growing interests in EPA Region 8: CO, MT, ND, SD, UT, and WY

• Look at environmental benefits from recycling more holistically

• What we expect: • Conservation of natural resources• Save landfill space• Decrease emissions of greenhouse gases (GHGs) and

other releases/impacts• Energy savings

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LIFE CYCLE ASSESSMENT (LCA)BASED STUDY

• Environmental life cycle assessment is a quantitative accounting of the cumulative environmental impacts of a product or process across all stages of the life cycle

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ProductDesign and

Manufacturing

Transportation

Energy, WaterInputs

Emissions to Air, Water, and Land

Renew RemanufactureRecycle Reuse Composting

ResourceExtraction

MaterialProcessing

DisposalCollection/Processing

ProductUse

Energy, WaterInputs

Energy, WaterInputs

Energy, WaterInputs

Energy, WaterInputs

Energy, WaterInputs

WHAT WAS THE GOAL?

• GOAL: To compare limited environmental inventory and impacts of seven (7) asphalt mixes with various percentages of reclaimed asphalt and recycled shingles to a baseline of virgin asphalt

EPA’s analysis is only an initial, limited life cycle inventory and impact assessment

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ABOUT REPORT AND KEY CONTENT

• Considers recovered materials and innovative technologies used in asphalt production

• Used regional characterization factors, where possible: (e.g. mix designs and distances to obtain materials and to transport pavement to the construction site)

• Inventory and impacts examined from material extraction to transport to the construction site:• Avoided landfill impacts• Greenhouse gas (GHG) emissions/Global Warming

Potential (GWP)• Criteria and other air pollutants

• Energy consumption and resource depletion are considered only for select stages in the life cycle

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SCOPE AND PROCESS DESCRIPTION

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Landfill

Industrial Waste

Shingles

Post - consumer Shingles

Shingles Grinder

Petroleum Extraction

Separation

Petroleum Refining

Asphalt Plant Loader Roadway Construction

RAP Processing

Roadway Removal

Aggregate Production

WHERE WAS THE DATACOLLECTED FROM?

• Local asphalt producers – energy and materials, mix designs

• National Renewable Energy Laboratory’s U.S. Life Cycle Inventory Database – fuels, electricity, transportation, equipment and process emissions

• National Institute of Standards and Technology’s Building for Environmental and Economic Sustainability (BEES) tool – sand and aggregate data

• EPA’s Waste Reduction Model (WaRM) – GHG savings information

• Intergovernmental Panel on Climate Change (IPCC) – global warming potentials

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MIX SCENARIOS

Scenario

Type ofMix

Design MixReferred

To As

1 HMA Virgin Materials Virgin

2HMA

Hot Mixed Reclaimed Asphalt Pavement (20%)

20% RAP

3WMA

Warm Mixed Reclaimed Asphalt Pavement (20%)

WMA 20% RAP

4HMA

20% Reclaimed Asphalt Pavement and 3% Recycled Asphalt Shingles

20% RAP-3% RAS

5HMA

20% Reclaimed Asphalt Pavement and 5% Recycled Asphalt Shingles

20% RAP-5% RAS

6HMA

20% Reclaimed Asphalt Pavement and 7% Recycled Asphalt Shingles

20% RAP-7% RAS

7HMA

17% Reclaimed Asphalt Pavement and 3% Recycled Asphalt Shingles

17% RAP-3% RAS

8 HMA 5% Recycled Asphalt Shingles 5% RAS

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SOME KEY ASSUMPTIONS

• Virgin aggregate is transported 36 miles, while recycled materials are transported 9 miles.

• Transportation to the construction site is 30 miles for all asphalt mixes except WMA 20% RAP, which is assumed to be transported 60 miles.

• RAP contains 4% binder and RAS contains 24.3% binder by weight.

• All mixes require binder from the petroleum refiners, have the aggregates heated using natural gas, and are mixed in a drum plant.

• The physical activities associated with placing, maintaining, and removing of the pavements, as well as the emissions from those activities, are assumed to be similar across all scenarios.

• All asphalt mixes are able to perform under the road conditions for which they are designed.

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RESULTS All results are reported with respect to the production of 1

short ton of asphalt transported to a road construction site.

ENERGY USE

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Energy Consumption During Select Life Cycle Stages

WMA 20% RAP = 12% energy reduction vs. HMA 20% RAP mix

RESOURCE DEPLETION

ScenarioVirgin Quantity(lb/short ton)

Recycled Quantity(lb/short ton)

Virgin 1,881 -

20% RAP 1,514 383

WMA 20% RAP 1,514 383

20% RAP-3% RAS 1,467 444

20% RAP-5% RAS 1,436 485

20% RAP-7% RAS 1,404 527

17% RAP-3% RAS 1,523 386

5% RAS 1,809 96

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Quantities of Virgin and Recycled Aggregates

AVOIDED LANDFILL IMPACTS

ScenarioMass Avoided(lbs/short ton)

Volume Avoided(cubic yards/short

ton)

Virgin 0 0

20% RAP 383 0.28

WMA 20% RAP 383 0.28

20% RAP-3% RAS 444 0.42

20% RAP-5% RAS 485 0.52

20% RAP-7% RAS 527 0.62

17% RAP-3% RAS 386 0.38

5% RAS 96 0.23

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Mass and Volume Reductions from Recycling RAS and RAP

GREENHOUSE GAS CREDIT FOR AVOIDED LANDFILL

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GREENHOUSE EMISSIONS

• When transportation to the construction site is assumed to be 30 miles for all asphalt mixes, there is a 3% reduction in GHGs when switching from the 20% RAP to the WMA 20% RAP.

• When transportation to the construction site is assumed to be 60 miles for the WMA 20% RAP (30 miles for all other mixes), the WMA 20% RAP GHG emissions are 9% higher.

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GLOBAL WARMING POTENTIAL

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GLOBAL WARMING POTENTIAL

Change (lbs CO₂e/short ton)

20% RAPWMA

20% RAP20% RAP,3% RAS

20% RAP, 5% RAS

20% RAP,7% RAS

17% RAP,3% RAS

5% RAS

With no Landfill Credit -8.1 5.8 -16.8 -21.6 -26.6 -16.9 -10.4

-5% 4% -10% -13% -16% -10% -6%

With Landfill Credit-23.0 -9.1 -34.0 -40.4 -47.0 -31.9 -14.2

-14% -6% -21% -25% -29% -19% -9%

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= mix with greatest reduction

= RAS mixes meeting CDOT specification

CRITERIA AND OTHER AIR POLLUTANTS

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AIR POLLUTANTS BY PROCESSFOR 20% RAP-5% RAS MIX

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CONCLUSIONS

• There are environmental benefits to the use of recycled asphalt shingles (RAS) in asphalt production for use in road construction.

• Larger reductions in impacts are seen when RAP is included over solely using RAS. The addition of RAP reduces the amount of virgin aggregate required which must be transported over a longer distance.

• Combining RAP and RAS diverts even larger volumes of material away from landfills, and these amounts are quantified in the study.

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CONCLUSIONS

• The addition of RAS to pavement mixes that use RAP helps further increase environmental reductions relative to the baseline of using virgin asphalt.

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Decreasing GWP as RAS Content Increases in HMA mixes

CONCLUSIONS

• Transport distances for aggregate and asphalt are both highly sensitive variables that can have large impacts on the total life cycle emissions.

• transportation distance for WMA from 30 to 60 miles raises the GHG emissions for transportation by 51% compared to the equivalent HMA case. The change is 19 lbs CO2e/short ton of asphalt, which is over 10% of the emissions considered in the study.

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Asphalt Plant

Aggregate Production

LoaderRoadwayConstruction

GOING FORWARD WITH RAS

• Asphalt shingles (and asphalt pavement) are 100% recyclable. • Recycling saves landfill space• Emissions of GHGs associated with operation and

transportation to the landfill are avoided• Upstream impacts from aggregate processing are

mitigated• Conservation of natural resources• Reduction of environmental pollution from material

extraction and processing• GHG and other air emissions from transport are

reduced due to less fuel consumption• Valuable oil is reused and upstream air emissions are

reduced• Win / win when used responsibly

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WHO CONTRIBUTED TO THE PEER REVIEWED REPORT?

• Peer consultation during development:

• Jarrett Welch – Brannon Sand & Gravel Co.

• Gary Stillmunkes – Asphalt Specialties Company Inc.

• William Turley – Construction Demolition & Recycling Association

• Dr. Howard Marks – National Asphalt Pavement Association

• Dr. Audrey Copeland – National Asphalt Pavement Association

• Peer reviewers of draft final report:

• Dr. Maryann Curran – U.S. EPA Office of Research and Development

• Marie Zanowick – U.S. EPA Region 8

• Dr. Alberta Carpenter – National Renewable Energy Laboratory

• Dr. Arunprakash Karunanithi – University of Colorado Denver

• Victor (Lee) Gallivan – Federal Highway Administration

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CONTACT INFORMATION AND REPORT

Kendra A. MorrisonU.S. EPA Region 8(303)312-6145morrison.kendra@epa.gov

Report can be obtained from EPA Region 8’s website: http://www2.epa.gov/region8/industrial-materials-recycling

Construction Demolition & Recycling Association (2013). C&D World. September/October, 6(5): 14-25.

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