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John A. D’AngeloUS Federal Highway Administration
CUPGA 2008Saskatoon, Saskatchewan
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How Many WMA Technologies are Available in the U.S.?
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Currently 12 Technologies Actively Marketed and Available in the U.S.
How Many WMA Technologies are Available in the U.S.?
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Warm Mix Trials and DemonstrationsWarm Mix Trials and Demonstrations
Trial completed
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There is a tremendous growth in interest in Warm Mix in the US
WHY?Fuel costs are up.
Bitumen cost have spiked.
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Change in Producer Prices for Construction Segments
Source: BLS (CPI, PPI)
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Change in Producer Price Indexes (PPI) for Highway Inputs
Source: BLS (CPI, PPI)
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Change in Producer Price Indexes (PPI) for Asphalt
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Economic Drivers for Using RAP
Growth in recycling occurs when it is economical to do so.
Warm Mix Technology can improve RAP workability.
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Fractionated RAP
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A review of some projects and what we have learned
Hall Street St. Louis
I70 Colorado
Entrance to Yellowstone
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Hall Street, St. Louis, MO
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St. Louis Paving ScheduleControl (12.5mm PG 70-22) – 5/17/06
Sasobit – 5/18/06
Sasobit – 5/19/06
Evotherm – 5/22/06
Evotherm – 5/23/06
Aspha-Min – 5/25/06
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Interstate 70, Dillon, CO
Dillon
70 miles West of Denver, CO
Elevation 8,800 – 11,100
Feet
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Mix Type
FieldProperty
Control 7-24-07AdveraWMA
Control 7-26-07Sasobit
Control 8-13-07Evotherm
Low AirTemp. (°F)
54 54 50 50 36 36
DeliveryTemp. (°F)
* 260 * 235 * 243
At ScreedTemp. (°F)
* 243 * 230 * 235
MatDensity
(% Rice)
93.8 93.3 95.7(single
data point)
93.2 93.7 94.7
* Minimum delivery temp for control HMA was 280 °F
Chart is Courtesy of CODOT
Interstate 70, Dillon, CO
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Construction Highlights Mix Type
Property
Control 7-24-07AdveraWMA
Control 7-26-07Sasobit
Control 8-13-07Evotherm
Results are from the CDOT QA lab – QC results were comparable FHWA’s mix flow number, dynamic modulus and binder test data are pending.
AC (%) 6.23 6.38 6.41 6.32 6.04 6.38
Voids (%) 3.1 1.8 3.0 2.4 3.6 2.2
VMA (%) 16.5 15.7 16.5 15.9 16.3 15.8
MatDensity
(% Rice)
~94 ~94 ~94 ~94 ~94 ~94
TSR (%) 100 83 *97 111 94 80
Stability 36 34 35 36 35 34
Hamburg(mm rut)
9.46 9.79 17.31 10.49 10.10 14.86
* Average of other control mix tested on the job.
Regardless of Hamburg Rut Depth, Moisture damage more prevalent in the WMA samples than the control samples – see following pictures
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ConclusionsWMA decreased voids in lab compaction
WMA field compaction comparable at lower temps
Hamburg moisture damage visibly more in WMA
Early WMA performance equal to HMA on the jobNo rutting, no early distresses
Confident that WMA facilitates cold temp. placement
Will use more WMA in this corridor if performance is comparable to HMA
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East Entrance, Yellowstone, WY
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Mixture Locations
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Control - 3.82 mm and 4.00 mm
Advera - 3.80 mm and 3.25 mm
Sasobit - 3.28 mm and 2.60 mm
*All the testing was performed at 40°C wet and reported at 20,000 passes.
Yellowstone Hamburg
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FLH-What Have We Learned
Field density achieved in all cases
Saved ≈ 20% in fuel at the plant
Temperature at plant hard to regulate
Mix handled similarly
Workers noted no handling difficulties
No smoke
Additives don’t seem to affect mix design
Sasobit stiffens binder
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Objective
Evaluate the effects of three Warm Mix process namely Sasobit, Aspha-Min and Evotherm on M320-Table 2 Performance Grade
To Compare the Performance Grades of Warm Mix processes with the base asphalt used in preparing warm mix asphalts
Binder Characterization
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Hall Street, St. Louis, MOM320 ContinuousPerformance Grade
M320, Table 2Performance Grade
Additive Rate, by wt of binder
Base 70.9 – 24.870.9 – 24.8 70 - 2270 - 22
w/ Sasobit 76.5 – 22.876.5 – 22.8 76 - 2276 - 22 1.5%
w/ Aspha-Min 72.4 – 24.672.4 – 24.6 70 - 2270 - 22 5.26%
Evotherm (recovered per ASTM D 6934)
66.6 – 26.766.6 – 26.7 64 - 2264 - 22
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FindingsSasobit – increase of one high temp. PG grade Aspha-Min - no effect on PG gradeEvotherm
recovered at BASF, no effect on the PG graderecovered from the stored emulsion, reduced by one high temp. PG grade
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Cost Example
Fuel usage2.12 gallons/ton of mix -- Control
1.62 gallons/ton of mix -- Advera
1.80 gallons/ton of mix -- Sasobit
• 20 to 25 % fuel savings ≈ $1/ton of mix
• Cost for Advera ≈ $3.30/ton of mix
• Cost for Sasobit ≈ $2.30/ton of mix• Cost occurred in August 2007
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WMA Technical Working Group (TWG)
Formed in 2005Formed in 2005Purpose:Purpose:
Promote Technology TransferPromote Technology TransferFacilitate Product Approval MethodsFacilitate Product Approval MethodsEncourage ResearchEncourage ResearchDevelop Quality and Environmental Testing Develop Quality and Environmental Testing ProtocolsProtocolsProvide Guidelines for Mix Design and Provide Guidelines for Mix Design and ConstructionConstructionIdentify Other Benefits of WMAIdentify Other Benefits of WMA
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www.warmmixasphalt.comMaterial Testing FrameworkEmission Testing FrameworkWMA Best Practices DocumentResearch Needs Identified
Developed three (3) research statementsSubmitted through AASHTO to NCHRP• All projects highly ranked by SCOR• Total $1.4 million
WMA TWG Accomplishments
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NCHRP Research ProjectsNCHRP Research Projects
NCHRP Project 09-43NCHRP Project 09-43““Mix Design Practices for Warm Mix Asphalt”Mix Design Practices for Warm Mix Asphalt”
$500,000.$500,000.0000
Advanced Asphalt Technologies, LLCAdvanced Asphalt Technologies, LLC
NCHRP Project 09-47NCHRP Project 09-47““Engineering Properties, Emissions, and Field Engineering Properties, Emissions, and Field Performance”Performance”$900,000.$900,000.0000
Principal Investigator: Asphalt InstitutePrincipal Investigator: Asphalt Institute
3434WMA SCAN 2007WMA SCAN 2007
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Warm Mix Asphalt: Best PracticesWarm Mix Asphalt: Best PracticesQuality Improvement Quality Improvement Series (QIP) 125Series (QIP) 125
Stockpile Moisture ManagementStockpile Moisture Management
Burner Adjustments and Burner Adjustments and EfficiencyEfficiency
Aggregate Drying and Baghouse Aggregate Drying and Baghouse TemperaturesTemperatures
Drum Slope and FlightingDrum Slope and Flighting
Combustion AirCombustion Air
RAP usageRAP usage
Placement ChangesPlacement Changes3535
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WMA US Implementation
To date trial projects have been place in over 50% of the US states.
The oldest projects are now 3 to 4 years old with no indication of poor performance.
Over 500,000 tons of WMA have been placed.
Two states want to use WMA as a alternative to Hot Mix now.
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WMA US Implementation
Major concernsPotential for moisture damage.
Long term durability.
Mix design changes.
Thank You
Questions
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