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Project Update SD2008-03 Evaluation of Warm Mix Asphalt Concrete Pavement in South Dakota Conditions John Foster SDDOT Office of Research Pierre, SD PI-Peter Sebaaly, University of Nevada-Reno Connecting South Dakota and the Nation 2012 SD Asphalt Conference Best Western - Ramkota Pierre, SD March 28-29, 2012
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Project Update SD2008-03 Evaluation of Warm Mix Asphalt Concrete

Pavement in South Dakota Conditions

John FosterSDDOT Office of Research

Pierre, SD

PI-Peter Sebaaly, University of Nevada-Reno

Connecting South Dakota and the Nation

2012 SD Asphalt ConferenceBest Western - Ramkota Pierre, SDMarch 28-29, 2012

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WMA Review

WMA is a process of producing bituminous mixture for pavements at a significantly ( 50-100° F) lower temperature than conventional HMA.

Reduce temperature requirements in production from 275-325 deg. F. (HMA) to 200-275 deg. F. (WMA)

Addition or combination of additives or modifiers to lower binder viscosity, promote coating of particles at lower temps

In excess of 15 WMA technologies currently available, at least 10 in the US.– Fiber/Organic– Chemical– Physical– Foamed/Foaming Agents

Limited use in United States until 2005• Nebraska, Colorado, Wyoming 2007• Used Widely in Europe

** Reduced viscosity allows the aggregate to be fully coated at a lower temperature than what is traditionally required in HMA production.

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WMA Review It’s All About Lowering the Temps…. ( 50-100° F)

– Reduced burner fuel/energy consumption– Preservation of binder properties - enhanced pavement life– Reduced emissions, odors/fumes at plant and job sites– Compliance- large metropolitan areas w/air quality restrictions

(non-attainment areas).– Improved working conditions, reduced hazards to workers– Improved workability– Enhanced in-place density under adverse conditions – Extend workability

• Longer haul distances• extended paving season

– More uniform mix - decreased thermal segregation– Potential for increased use of RAP

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Double Barrel Green, Aquafoam, Gencor Ultrafoam GXTM

Foaming nozzles inject water into the mixing chamber~One pound of water per ton of mix

Water-Based TechnologiesProcess- Water injection at point where binder enters drum promotes asphalt foaming to coat particles

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Water-Fixating Additives

2/28/2014

Advera – Hydrated Synthetic Zeolite (18-21% water)– 0.25-0.3% of mix (5 lb’s) Advera per ton of AC– Captured moisture released as steam - produces

time-release foaming of the asphalt binder – Steam droplets improve workability

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Chemical Additive

EvothermEvotherm 3G (third generation) - water-free form of Evotherm can be introduced at the mix plant or asphalt terminal.

– In-line injection with the binder-- added capabilities– 5% by weight of binder recommended– Evotherm -modified binder performance matches, or may surpass

qualities of conventional HMA binder – Allows higher percentages of recycled asphalt (RAP) to be used.

2/28/2014

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Warm Mix Asphalt (WMA)Topics of Special Interest to SDDOT

– Allowance for SD’s Construction Season, Materials, & Environment• More effective late season paving• Flexibility in portable plant setups…longer hauls

– Cost Savings• Burner fuel usage• Equipment fuel usage• Gained efficiencies >>increased flexibility in project planning• Potential for expanded use of RAP

– Long term benefits:• Extended pavement life• Improved Pavement Quality

– Possible Winter Season Wearing Course– Cold Weather Patching– Air Quality & Jobsite Exposure Issues

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SD2008-03 Project Goals

Problem: Assess Performance Evaluate the suitability of Warm Mix Asphalt (WMA) in SD

conditions (aggregates, binders, additives, climate extremes) Assess WMA suitability in all paving applications (e.g. overlays,

leveling, interim, patching) Evaluate WMA properties (material components & mixture) Evaluate WMA pavement integrity, durability & workability

characteristics relative to HMA over time Evaluate emissions of WMA /vs. HMA during paving & production Link to thermal imaging applications (construct maps, correlate

thermal properties with other data) Cost - benefit analyses relative to the constructability,

performance, environmental factors, other considerations Link to ongoing MEPDG activities (strength/mechanistic

properties) Link to increased recycled asphalt pavement material usage

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Project Review (cont)

Research Approach– Literature & Process Evaluation- Build Off of Existing Regional

Experience (Wyo.-YNP, Colorado- I 70, Nebraska – NE12)– Laboratory Designs/Protocol/Testing– Preliminary Demonstrations in 2009– Test Sections for Performance Evaluation 2010, 2011– Extended Test Section Performance Evaluations for 2

years– Emissions Testing Phase– Generate Final Report, Formulate Recommendations – Develop Implementation Plan – Duration 4/5 years– Budget: $140,000

Perspective: Approx. $150MM-$200MM invested in HMA Pavements in SD Annually

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Mix Type None Advera Evotherm Foamed

LimestonePG64-28

X X X X

Quartzite PG64-28

X X X X

Nat. Gravel PG64-28

X X X X

Test Matrix

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Milestones Completed WMA processes researched & evaluated, 3- technologies

selected

WMA research and literature identified & evaluated

Technical panel meetings & progress reports

Developed lab protocol & testing plan - preliminary lab results

Developed field testing evaluation protocols

Test sections constructed at three locations using three WMA technologies, side-by-side control sections

Preliminary emissions data

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Laboratory Evaluation Western Regional Superpave Center

Evaluate suitability of various WMA technologies using South Dakota aggregate sources and binder types in various applications. Assess:

• optimum WMA temperatures• aggregate blend gradation • number of gyrations (for mixture classifications Q1-Q5)• binder content • verify coating • moisture sensitivity at selected design binder content • rutting resistance - Asphalt Pavement Analyzer (APA) test and the Flow

Number (FN) test.• mechanical properties - dynamic modulus |E*| is an indicator of resistance

to fatigue cracking and rutting.

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Preliminary WMA Trials in 2009

Access roads and tie-in to parking lot - Turtle Creek Store, Mission, SD Nov, 2009 Mix produced by Morris plant , Pierre 100 mile haul Evotherm (0.5%) added to extend compaction window Results promising

Shoulder Reconstruction - I90 near Cactus Flats Nov, 2009 IM-0902(145)112-Shoulder Reconstruction Mix produced by Hills Materials 60 mile haul-long cycle time E mix-30% RAP PG 58-28 Terex Foaming Unit

– No production rate control of water addition-nominal setting Results - some degree of pavement failure

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Hwy 73 Project

Hwy 73 Test Section

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•Contractor- Border States•Cloudy, breezy, some rain, ambient ~60°F•PG64-28 binder (5.7%)•Aggregate moisture 3% - 4.4% •Standard Gyratory QA/QC protocols•HMA: 275-315°F •WMA: initially at 275°F, dropped to 250-270°F•WMA Foamed (Gencor Ultra EX) - 2500 tons

•WMA Evotherm 3G – 2400 tons•HMA control sections side-by-side •10-mile haul: 250-275°F at plant, 230-260°F front of paver, 225-255 °F behind paver•Grid layout for nuclear readings at random core locations(1000 ton sublot)•Avg. HMA fuel usage – 1.79 gal/ton < > Avg. WMA fuel usage – 1.87 gal/ton•HMA lab densities 95% < > WMA lab densities 94.5%•Consistent roller pattern (target +140°F):

• Breakdown- majority of compaction• intermediate 1% per pass •finish 0.5%

• Roller operator noted improved workability•Maintenance patching: HMA @85.1 & 87.8%, WMA 86.4%

Hwy 73 Project – Spring, 2010

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Hwy 20 & Hwy 79 Projects

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Hwy 20 & Hwy 79 WMA Test SectionsBison, SD

Contractor- Anderson Western Late May, 2010 Cloudy, very windy, ambients 60-70°F PG64-28 binder (5.3%) Class Q2 mix Aggregate moisture content high (?%) HMA: 275-315°F WMA: initially at 275°F, dropped to 250-270°F HMA control sections at either end and along side 0 – 40 mile haul: 275°F at plant, 260°F front of paver, 255 °F behind paver Standard gyratory QA/QC testing protocols Fuel usage – HMA -1.82 gal/ton, Evotherm WMA 1.62 gal/ton, Foamed WMA 1.72 gal/ton. Total

burner fuel savings $4800 density achieved with less effort, fewer roller passes Roller operators noted that the Evotherm WMA felt softer than the HMA and the Foam WMA. Bumps

are less sharp. Finish rolling temperatures as low as 135 (Evotherm) to140 ( Foamed). Rollers were able to remove

marks at even lower temps.

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Hwy 20 & 79 – Bison, SD

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Pine Ridge/Oglala - Shannon CountyHwy 18 Demonstration

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Pine Ridge/Oglala - Shannon CountyHwy 18 Demonstration

Contractor- Border States Jul- late Oct, 2011 WMA- Later Oct; Cloudy, windy, cold (ambients 14-65°F) Oct 26th : 14°F at 07:30 AM, start paving at 10:30 (~32?) Some problems at startup PG64-34 binder (~5.3%) Class Q2 mix Aggregate moisture content ranged from 4%-5.5% HMA: 275-315°F WMA: 250-275°F at plant, 260°F front of paver, 255 °F behind paver HMA control sections at either end and along side 0 – 15 mile haul Standard gyratory QA/QC testing protocols Fuel usage – rough est. > HMA 1.8-2 gal/ton, WMA 1.4-1.6 gal/ton Stack testing – AET 1st experience w/Thermal Maps Results –bumpy start for Evo

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Advera Injection Setup

WMA Technology

Aqua Foam Unit

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Emissions Monitoring

Stack Testing:• Stack emissions during production runs• U.S. EPA stack emissions testing protocols• Certified tester (AET- Minneapolis)• 60 min test runs• HMA and WMA comparative test runs• QA/QC Program• Test for:

• NOx (Method 7E)• CO2 (Method 3A)• VOC (Method 25A)

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Operating Parameters Monitored:• average production rate (tons/hr)• drag slat amperage• fuel usage• stack gas volumetric flow rates• temperature• moisture content

NOx is a generic term for the mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide). They are produced from the reaction of nitrogen and oxygen gases in the air at high temperatures. NOx eventually forms nitric acid, which contributes to acid rain.� CO2 -- carbon dioxide is one of the most significant causes of globalwarming. Asphalt binder contains carbon, which, when combusted, bonds with oxygen and forms carbon dioxide that enters the atmosphere.� VOCs are volatile organic compounds which are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, including benzene, toluene, and xylenes, some of which may have short and long-term adverse health effects.

 Run 1 Run 2 Run 3 Average

HMA Emissions (PG64-22, Production Temp = 290F) – Tuesday, Oct. 18th 2011NOx( lbs./hr) 11.6 10.7 11.0 11.1 CO2 ( lbs./hr) 11,928 12,692 12,554 12,391

VOC (lbs./hr) as propane 55.4 109.7 62.3 75.8 WMA-Advera Emissions (PG64-34, Production Temp = 260F) – Wednesday, Oct. 19th 2011

NOx( lbs./hr) 11.3 11.0 11.6 11.3 CO2 ( lbs./hr) 11,986 10,349 11,051 11,129

VOC (lbs./hr) as propane 71.8 57.7 57.3 62.3 WMA-Advera Emissions (PG64-34, Production Temp = 270F) – Thursday, Oct. 20th 2011

NOx( lbs./hr) 14.1 10.8 9.5 11.5 CO2 ( lbs./hr) 11,985 12,260 12,056 12,100

VOC (lbs./hr) as propane 70.1 63.8 71.2 68.4  

• NOx levels fairly equivalent for HMA & WMA • Decrease in measured CO2 and VOC observed with

decrease in production temperatureTest Results

Stack Emissions

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Job Site Emissions - plan

Quantify asphalt fume emissions in vicinity of paver – Traditional gravimetric procedures (NIOSH Method 5042) Airborne total particulate (TP) material and benzene-soluble fraction (BSF) Clip-on monitors Monitor atmospheric conditions - wind speed/direction, air temp, humidity

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Impact on Emissions

EmissionPercent Reductions relative to HMA

Norway Italy Netherlands France Canada SD∆T=30º F

Carbon dioxide: CO2 31.5 30-40 15-30 23.0 45.8 18

Sulfur dioxide: SO2 NA 5.0 NA 18.0 41.2 NA

Volatile organic compounds: VOC NA 50.0 NA 19.0 NA 47%

Carbon monoxide: CO 28.5 10-30 NA NA 63.1 NA

Oxides of nitrogen: NOx 62.5 60-70 NA 18.0* 58.0 0

Dust 54.0 25-55 NA NA NA NA2/28/2014

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WMA Hwy 18 – Pavement Density Check

Station Lane Point Offset Density Gauge UW

Est. Density (%)

250+00 EB 1.5 ft. Right 148.6 96.4

“” “” 6.5 ft. Right 147.9 96.0

“” “” 12.5 ft. Right

147.0 95.4

205+00* EB 1.5 ft. Right 144.7 93.9

“” “” 6.5 ft. Right 147.9 96.0

“” “” 12.5 ft. Right

146.4 95.0

204+00* EB 12.5 ft. Right

147.4 95.6

203+00* EB 12.5 ft. Right

147.5 95.7

Evotherm

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MOBA Pave IREstablished relationship between thermal signature and density

Mapping of Thermal Profiles • Easy to retrofit • User friendly• Built rugged for mobile applications• Can retrofit to any screed

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Data from US 18 Ogallala-Pine Ridge Border States Paving: 10/23/2011 (Foamed WMA)

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Lab Experimental Plan

12/28/2011 University of Nevada Reno, www.wrsc.unr.edu 29

Mechanical Properties Evaluated:1. Resistance of the mixtures to moisture damage

(stripping). TSR ratio2. Resistance of the mixtures to rutting APA & FN 3. Mixtures dynamic modulus (ІE*І)

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Experimental Plan (PG64-28)- Process (1.5% by weight of binder) Advera (0.3% by TWM)- Evotherm 3G (0.5% by weight of binder)- Plant Foaming

12/28/2011 University of Nevada Reno, www.wrsc.unr.edu 30

* Not Tested (short on materials)

Mixture

Aggregate source Short‐Term Oven Aging Conditions

Quartzite LimestoneNatural  Gravel

Volumetric Performance

HMA X X X 2hrs @ Comp. Temp 4hrs @ 275 °F

WMA‐Advera X X X 2hrs @ Comp. Temp 2hrs @ Comp. Temp

WMA‐Evotherm X X X 2hrs @ Comp. Temp 2hrs @ Comp. Temp

WMA‐Foaming X X X 2hrs @ Comp. Temp 2hrs @ Comp. Temp

HMA‐2hrs STOA X X NT* 2hrs @ Comp. Temp 2hrs @ 275 °F

HMA‐Low Temp X X X2hrs @ WMA Comp. 

Temp2hrs @ WMA Comp. 

Temp

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Comments- Prelim. Lab Data

12/28/2011 University of Nevada Reno, www.wrsc.unr.edu 31

• Reduced mixing and compaction temperatures were achieved - up to 75°F below typical HMA production temps.

• WMA mixtures found to be workable and easy to compact compared to HMA mixtures.

• Lower production temperature and short-term conditioning had significant influence on the mixtures performance.

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Resistance to Moisture Damage> WMA & HMA mixtures exhibited satisfactory moisture resistance> HMA mixtures stiffer (higher ITS) than WMA mixtures> Quartzite aggregate mixes slightly stiffer (higher ITS) than the other aggregates

12/28/2011University of Nevada Reno, www.wrsc.unr.edu32

Natural Gravel Aggregate

143

105 105 98 104

125

89 9080

93

87 85 8582

90

0

10

20

30

40

50

60

70

80

90

100

0

20

40

60

80

100

120

140

160

180

200

HMA WMA‐Advera WMA‐Evotherm WMA‐Foaming HMA‐low Temp

Tensile

 Stren

gth Ra

tio at 7

7°F (25°C), %

Tensile

 Stren

gth ITS at 77°F (25°C), p

si

Mixture Type

Dry ITS, psi Wet ITS, psi Tensile Strength Ratio (TSR)

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Resistance to RuttingDifferent WMA mixtures exhibited acceptable rut resistance inboth APA and FN tests compared to HMA mixtures under same conditions

12/28/2011University of Nevada Reno, www.wrsc.unr.edu33

APA Test Results (AASHTO TP63)

3.91

5.14

3.96

5.92

3.57

4.29

2.32

4.16 4.21 4.03

2.45

4.36

2.56

3.28 3.27

4.41

3.43

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

HMA WMA‐Advera WMA‐Evotherm WMA‐Foaming HMA‐2hrs STA HMA‐low Temp

APA Ru

t Dep

th at 1

47°F (6

4C), m

m

Quartzite Lime Stone Natural Gravel

4.5 ± 0.5 % air voids.

Max. Rut depth for Q2 mix class is 7.0 mm.

Test Temperature = 64°C

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12/28/2011University of Nevada Reno, www.wrsc.unr.edu34

Limestone Aggregates

1

10

100

1,000

10,000

1.E‐03 1.E‐02 1.E‐01 1.E+00 1.E+01 1.E+02 1.E+03

Dynam

ic M

odulus |E*| at 70F, ksi

Reduced Frequency, Hz

HMA Advera Evotherm Foaming HMA‐2hrs STA HMA‐Low Temp

Evotherm

HMA

stiffer

Dynamic ModulusIn general, the dynamic modulus of WMA mixes was lower (less stiff) compared to HMA mixtures, but similar or higher (more stiff) than HMA-Low Temp

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WMA Activities in the Region

Similar to SD, Nebraska has full-blown research project….– SD > extended performance monitoring– SD> emissions testing

Montana, ND, Wyoming, & MN sponsoring demonstrations or already SOP

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Lessons Learned…..

There seems to be no single WMA technology that is ideal in every situation…..

Selection of technology involves trade-offs…. • Foaming >>Up front capital outlay, no material costs • Evotherm >>No equipment costs, higher material cost,• Evotherm >superior performance under extremes• Foaming> utility at the cost of moderate performance

Adverse conditions >> less forgiving ….. • Better handle on project constraints - narrowed paving window, freeze-up• Logistical things (materials, haul distance, equipment, personnel)• Plant production – increased sensitivity to interruptions

Budget – increased life cycle benefit comes at a price

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Yet to Be Verified….

Resistance to long-term rutting and cracking…..”jury still out”

Cost effective?…. Encouraging indications “short term” > production increases, extended

paving window, workability, increased flexibility in operations, hazards to workers, emissions, fuel savings

“long term” > aging factor,

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Challenges Project selection continues to be a “dynamic’ process Operational constraints of plants

• Need to maintain temperatures• Aggregate bin freezeup• Monitoring of fuel usage

Representative samples for lab analysis (foamed)? Need for better planning/communication under adverse

conditions Emissions monitoring results > perplexing Overcoming convention – “why fix it?”

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Planned 2012 Activities? Concentrate on long-term performance

monitoring, characterization of cores Convene technical panel to review project Continue data collection activities- lab/field

– More emissions testing?– Fatigue, rutting, surface profiling, etc.

Construct additional test sections??<Requirements>

– Virgin quartzite aggregate (no RAP in mix)– performance grade binder (PG64-28/PG64-34)– Q2 mix– Sufficient quantities for reasonable test

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Technical Panel Bill Anderson, Pennington Co. Dave Anderson, Local Govt. Kevin Carlson, Jebro Wayne Cramer, SDDOT-Aberdeen Region Brett Hestdalen, FHWA Ryan Johnson, SDDOT-Operations Support Daris Ormesher, SDDOT-Research Rick Rowen, SDDOT-Materials & Surfacing Ken Skorseth, SDLTAP Jason Smith, SDDOT-Materials & Surfacing Ken Swedeen, DAPA

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Questions?????


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