Transcript A Computer-Based Multimedia Pavement Training Concept for

Warm Mix Asphalt
Observations from the WSDOT I-90 Job (June 2008)
1. Where are we with WMA?
2. What do we know and not know?
3. Life cycle assessment
4. I-90 Observations
Where are we at with WMA technology?
WMA has been around in its current iteration since about
the mid 1990s but has existed in some for or another for at
least 30 years.
1970s
1995
2009
WMA standard use
starts in some places
Older WMA-like products
Boeing and others
current WMA starts
Plant foaming methods
MAXAM
AquaBlack
Foaming attachment
Terex Roadbuilding
Warm mix asphalt sys.
Foaming attachment
Astec Industries
Double Barrel Green
Foaming attachment
Gencor Industries
Green Machine
Foaming attachment
Kolo Veidekke
WAM Foam
Foaming process
Aspha-min
Aspha-min
Zeolite powder
PQ Corporation
Advera
Zeolite powder
Sasol Wax
Sasobit
Wax pellets
McConnaughay
Low energy asphalt
Chemical process
LEA CO
Low energy asphalt
Chemical process
Akzo Nobel
Rediset WMX
Surfactant pellets
Arkema Group
CECABASE RT
Surfactant chemicals
Meadwestvaco
Evotherm
Surfactant chemicals
Material foaming
Additives
The classic WMA benefits are enticing.
1. Reduced plant fuel consumption
2. Reduced emissions
– At the plant
– Fugitive emissions
3. Reduced viscosity during construction
– Better compaction
– Longer haul distances
– Cold weather paving
4. Same viscosity during operation
– Some have greater viscosity
What do we know and not know?
Based on published reports and presentations,
here’s what we think we know.
Item
Evidence
Results
Field
Performance
Older jobs: Europe (some > 10 yrs)
Newer jobs: Europe and U.S.
APT: NCAT, Caltrans PRC, others
≥ HMA
(not positive yet)
Laboratory
Performance
NCAT, State DOTs, Europe
•Some moisture issues
•Can be overcome
Energy Use
Europe, U.S. trials
10-30% less
Emissions
Europe, U.S. trials
(far fewer data points)
10-70% reduction depending
upon compound
Fumes/smell
Europe (experiment)
U.S. (mostly visual)
30-50% PAH reduction
Compaction
Europe
Numerous U.S. trials
≥ HMA
Aging
Some lab work, some speculation
Less aging
What do we not yet know to our satisfaction?
Item
Unknown
Help
Field
Performance
Long-term performance
APT (NCAT, Caltrans PRC)
NCHRP Project 09-47
Laboratory
Performance
Mix design
Characterization tests
NCHRP Project 09-43
NCHRP Project 09-47
Energy Use
Good protocol for quantification
Life cycle assessment (LCA)
NCHRP Project 09-47
Emissions
Good protocol for quantification
Life cycle assessment (LCA)
NCHRP Project 09-47
Fumes/smell
Quantification is very complex
Simple method needed
NCHRP Project 09-47
Compaction
Europe
Numerous U.S. trials
≥ HMA
NCHRP Project 09-47
Aging
Aging effects of WMA
Less aging
Specification
Best way(s) of doing it
TWG
Leader states (e.g., TX)
A “life cycle assessment” can help assess the
energy, environmental and materials picture.
Life cycle assessment (LCA) is a good tool to assess the
overall life cycle impact of WMA.
Life cycle assessment (LCA)
A protocol to assess the environmental, economic,
and social impacts of an industrial system.
The life cycle of the industrial system extends from cradle-tograve: from materials acquisition and production, through
manufacturing, system use and maintenance, and finally through
the end of the system’s life.
Essentially an accounting tool.
refinery
transport
transport
oil extraction
other inputs
Aggregate Quarry
transport
hma plant
water
fuel
other outputs
placement
emissions waste hazardous
waste
transport
An example of LCA processes,
inputs and outputs to consider for
HMA paving.
For a given unit of production (e.g., 1 lane-mile of
pavement) a typical LCA gives a range of outputs.
•
•
•
•
Amount of materials used (tonnes)
Total energy use (MJ)
Water consumption (kg)
Emissions
–
–
–
–
–
Global warming potential (tonnes of CO2 equivalent)
Nitrogen oxides – NOx (kg)
Sulfur dioxide – SO2 (kg)
Particulate matter – PM10 (kg)
Carbon Monoxide – CO (kg)
• Toxic things
–
–
–
–
–
Human toxicity potential
Mercury – Hg (g)
Lead – Pb (g)
Hazardous waste (kg)
Polycyclic aromatic hydrocarbons (PAHs)
An example of a LCA output relating to energy
consumption in pavement construction.
Amount of Energy Required to Build 1 Lane-Mile of Pavement
Notes:
•90%+ from manufacturing
•Numbers change a lot depending on assumption
Raw Materials Extraction
Manufacturing
Placement
Pavement
9-inch CRC Pavement
CRCP
(6 inches base material)
12-inch HMA Pavement
HMA
(6 inches base material)
3%
3% 3.7 TJ
94%
7%
2% 3.0 TJ
91%
Amount of energy consumed by 100 US households in a year (4 TJ)
- On average, a US household consumes 11,000 KWh of energy per year
- Does not include anything outside of the house (e.g., cars, fuel, etc.)
0
1
2
3
4.0 TJ
4
Total Energy Consumed (TJ)
Data from: Zapata and Gambatese, Energy Consumption of Asphalt and Reinforced Concrete Pavement Materials and
Construction, J. of Inf. Sys., vol. 11, issue 1, p. 9-20.
An example of a LCA output relating to the contribution of
different processes to environmental outcomes.
Contribution of Main Processes on Environmental Impacts of HMA
Hassan, M.M. (2009). Life-Cycle Assessment of Warm-Mix Asphalt: An Environmental and Economic
Perspective. Presentation at the 88th Annual Meeting of the Transportation Research Board,
Washington, D.C., 11-15 January, 2009.
An example of a LCA output relating to waste
production in roadways.
Waste Generated by 1 Lane-Mile of Pavement
Notes:
•Most from manufacturing and EOL
•Numbers change a lot depending on assumption
Extraction
Manufacturing
9-inch
CRC Pavement
(6 inches base)
1%
41%
10-inch
HMA Pavement
(15 inches base)
1%
38%
Construction
End of Life
6%
52%
2,225 tons
2%
59%
Waste from 1,000 average US households/yr
2,000 tons
- On average 2 tons/household/yr
0
500
1,000
1,500
2,852 tons
2,000
2,500
3,000
Waste Generated (Tons)
Data from: Rajendran and Gambatese, Solid Waste Generation in Asphalt and Reinforced Concrete Roadway Life Cycles, J. of Inf.
Sys., vol. 13, issue 2, p. 88=96.
7
Total Energy Use for 1 lane-mile of HMA pavement
maintenance
6
6.02
placement
manufacturing
5.37
extraction
5
Total Energy (TJ)
4.46
3.85
4
3.03
3
2.17
2.21
1.05
0.97
0.78
0.05
2.05
1.68
2
2.78
2.88
1.99
Structure (inches)
1
0
1.80
0.20
Zapata, Gambetese (2005) Mroueh, et al. (1999)
1.48
0.64
Hoang et al. (2005)
Athena (2006)
Athena (2006) 20% RAP
0
12
24
= HMA
= Base
= Subbase
LCAs are a defensible protocol for quantifying the energy,
environmental and materials aspects of WMA.
• Account for all processes associated with HMA
– Include WMA additive production/transport
– Include human health benefits beyond criteria pollutants
• Isolate improvements attributable to WMA
But…there are issues with the way we do LCA.
• Functional unit
– describes the function and performance of the
subject of the product or process being studied
– Example: 1 lane-mile of pavement capable of
supporting 100 million ESALs over 50 years
Implies
1. Structural design
2. Traffic measurement
3. Defining maintenance/rehabilitation methods
4. Performance standard
And…we are missing a good chunk of the data we need to
calculate a good LCA and it is expensive to get this data.
Process
Data Source
Issues
Fuel/Energy
GREET
Generic vehicle types
Transport
GREET
Generic vehicle types
Asphalt Production
Eurobitume
Dated European data
Aggregate Production
Eurobitume
Dated European data
HMA Production
EPA AP-42
Eurobitume
Only data for average plant
Cannot differentiate by process
Laydown
EPA NONROAD Uses generic engine hp sizes
WMA Additive
None
No good information
GREET: Greenhouse Gases, Regulated Emissions, and Energy Use in
Transportation Model from Argonne National Laboratories
Eurobitume: LCI report for Eurobitume (European-type Asphalt Institute)
EPA NONROAD: EPA emissions model for non-road vehicles
EPA AP-42: EPA emissions factors (emissions tied to quantity of material)
The I-90 Sasobit WMA job (June 2008)
12,500 tons
½-inch Superpave
0.25-ft mill-and-fill
Right lane only
Key Parameters
HMA Class ½-inch
WMA Class ½-inch
Binder content
5.2%
5.2%
Binder type
PG 76-28
PG 76-28 (83-28 w/Sasobit)
Gyrations
100
100
RAP content
20%
20%
Tonnage
7,781 tons
4,724 tons
Sasobit
0
2% by binder weight
Cost/ton
$58.00
$64.10
Production temp 340-350°F
300°F
Laydown temp
300-330°F
270-300°F
CPF
1.03
1.04
Compaction PF
1.02-1.05
1.03-1.05
Average density
93.60% of Rice
93.67% of Rice
Fuel usage
1.4 gal/ton (diesel)
1.07 gal/ton (diesel)
23.5% less
Roller pattern
5-8 passes in 30 min
same
HMA: 12 June 2008
HMA: 12 June 2008
WMA: 23 June 2008
WMA: 23 June 2008
Open Path FTIR
Preliminary LCA results from I-90
Grant County power mix.
This is one of the cleanest mixes in the nation.
Coal
8.21%
Natural Gas
3.06%
Nuclear
5.52%
Hydro
82.84%
Other (Solar, Wind,
Biomass, etc.)
1.35%
A few observations.
• Mix temperature drives everything
– We can gather less data and get same value
• How to simplify
– Report mix temperature
• Temperature vs. criteria pollutants for types of plants
• Temperature vs. vapor pressure for HMA compounds
• Temperature vs. vapor pressure is NOT linear
• The first 50°F is bigger than the second 50°F
– Report burner performance
– Report fuel usage
Summary
• We have learned a lot about WMA
• LCA can provide a defensible protocol for
analyzing environmental/energy factors
• Need to gather a few pieces of information
to reduce the environmental data needed
– HMA temperature vs. criteria pollutants
– HMA temperature vs. asphalt fumes