Analysis of Recycling Asphalt Shingles
in Pavement Mixes from a Life Cycle
Perspective
Kendra A. Morrison, U.S. EPA Region 8
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
2
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
Renew
Recycle
Energy,
Water
Inputs
Energy,
Water
Inputs
Resource
Extraction
Material
Processing
Remanufacture
Energy,
Water
Inputs
Composting
Reuse
Energy,
Water
Inputs
Product
Design and
Manufacturing
Product
Use
Energy,
Water
Inputs
Collection/
Processing
Energy,
Water
Inputs
Disposal
Transportation
Emissions to Air, Water, and Land
3
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
4
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
5
SCOPE AND PROCESS DESCRIPTION
Industrial
Waste
Shingles
Shingles
Grinder
Aggregate
Production
Post-consumer
Shingles
Separation
Asphalt Plant
Loader
Petroleum
Extraction
Petroleum
Refining
RAP
Processing
Roadway
Removal
Landfill
Roadway
Construction
6
WHERE WAS THE DATA
COLLECTED 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
7
MIX SCENARIOS
Scenario
Type of
Mix
1
HMA
Virgin Materials
2
HMA
Hot Mixed Reclaimed Asphalt Pavement (20%) 20% RAP
WMA
Warm Mixed Reclaimed Asphalt Pavement
(20%)
WMA 20% RAP
HMA
20% Reclaimed Asphalt Pavement and 3%
Recycled Asphalt Shingles
20% RAP-3% RAS
HMA
20% Reclaimed Asphalt Pavement and 5%
Recycled Asphalt Shingles
20% RAP-5% RAS
HMA
20% Reclaimed Asphalt Pavement and 7%
Recycled Asphalt Shingles
20% RAP-7% RAS
HMA
17% Reclaimed Asphalt Pavement and 3%
Recycled Asphalt Shingles
17% RAP-3% RAS
HMA
5% Recycled Asphalt Shingles
5% RAS
3
4
5
6
7
8
Design Mix
Referred
To As
Virgin
8
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.
9
RESULTS
All results are reported with respect to the production of 1 short
ton of asphalt transported to a road construction site.
10
ENERGY USE
Energy Consumption During Select Life Cycle Stages
WMA 20% RAP = 12% energy reduction vs. HMA 20% RAP mix
11
RESOURCE DEPLETION
Quantities of Virgin and Recycled Aggregates
Virgin 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
Scenario
12
AVOIDED LANDFILL IMPACTS
Mass and Volume Reductions from Recycling RAS and RAP
Mass Avoided
(lbs/short ton)
Volume Avoided
(cubic yards/short ton)
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
Scenario
Virgin
13
GREENHOUSE GAS CREDIT FOR
AVOIDED LANDFILL
14
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.
15
GLOBAL WARMING POTENTIAL
16
GLOBAL WARMING POTENTIAL
Change
(lbs CO₂e/short ton)
With no Landfill Credit
With Landfill Credit
20% RAP
WMA
20% RAP
20% RAP,
3% RAS
20% RAP,
5% RAS
20% RAP,
7% RAS
17% RAP,
3% RAS
5% RAS
-8.1
5.8
-16.8
-21.6
-26.6
-16.9
-10.4
-5%
4%
-10%
-13%
-16%
-10%
-6%
-23.0
-9.1
-34.0
-40.4
-47.0
-31.9
-14.2
-14%
-6%
-21%
-25%
-29%
-19%
-9%
= mix with greatest reduction
= RAS mixes meeting CDOT specification
17
CRITERIA AND OTHER AIR
POLLUTANTS
18
AIR POLLUTANTS BY PROCESS
FOR 20% RAP-5% RAS MIX
19
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.
20
CONCLUSIONS
Decreasing GWP as RAS Content Increases in HMA mixes
• The addition of RAS to pavement mixes that use RAP helps
further increase environmental reductions relative to the
baseline of using virgin asphalt.
160
Global Warming Potential
(lbs CO₂e/short ton)
140
120
100
80
60
40
20
0
0%
1%
2%
3%
4%
5%
6%
7%
21
CONCLUSIONS
• Transport distances for aggregate and asphalt are
both highly sensitive variables that can have large
impacts on the total life cycle emissions.
Aggregate
Production
Asphalt Plant
•
Loader
Roadway
Construction
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.
22
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
23
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
24
CONTACT INFORMATION AND REPORT
Kendra A. Morrison
U.S. EPA Region 8
(303)312-6145
morrison.kendra@epa.gov
Report can be obtained from EPA Region 8’s website:
http://www2.epa.gov/region8/industrial-materialsrecycling
Construction Demolition & Recycling Association
(2013). C&D World. September/October, 6(5): 14-25.
25