WMA by vSbWKZ2S

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									Warm Mix Asphalt
                        CEE597 Pavement Construction & QC




Outline

 •   What WMA does
 •   WMA technologies
 •   WMA benefits
 •   WMA issues
                                                    CEE597 Pavement Construction & QC




HMA Mixing & Placement Temperatures


   Hot Mix Asphalt
   350°F
                     Standard Mixing Temperature
   300°F                 • Dry aggregate
                         • Coat aggregate with asphalt
   250°F
                     Standard Placement Temperature
   200°F                 • Lower viscosity
                         • Good workability
   150°F

   100°F

    50°F
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Basic WMA Premise

 Reduce the viscosity of the mix during
 production so that complete aggregate
 coating can occur at a lower temperature.
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Resulting WMA Benefits

 • Reduced plant fuel consumption
 • Reduced emissions
   – At the plant
   – Fugitive emissions
 • Reduced viscosity during construction
   – Better compaction
   – Longer haul distances
   – Cold weather paving
 • Same viscosity during operation
   – Sasobit: greater viscosity at high temps
                                          CEE597 Pavement Construction & QC




Typical Temperatures

  Hot Mix Asphalt                  Warm Mix Asphalt
  350°F                                         350°F
                    Plant Mixing
  300°F                                         300°F

  250°F                                         250°F
                    Construction
  200°F                                         200°F

  150°F                                         150°F

  100°F                                         100°F

   50°F                                         50°F
                                          CEE597 Pavement Construction & QC




WMA Technologies

 • Plant foaming technologies
   – BP WAM-Foam
   – ASTEC Double Barrel Green
 • Material foaming technologies
   – Aspha-min (Hubbard Construction)
   – Advera (The PQ Corporation)
   – Low energy asphalt (McConnaughey)
 • Additives
   –   Sasobit (Sasol)
   –   Evotherm (MeadWestvaco)
   –   Revix (Mathy Construction/Ergon)
   –   Rediset (Akzo-Nobel)
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WAM Foam

• Kolo Veidekke (Norway)
• 2-stage process
  – 1st stage: softer binder
  – 2nd stage: harder binder
                foamed
• Needs plant modification
• Proprietary



                               photo from Kolo Veidekke website
                                                 CEE597 Pavement Construction & QC




ASTEC Double Barrel Green




    See the video:
    http://www.astecinc.com/video/green/DB_Green.htm
                               CEE597 Pavement Construction & QC




Aspha-Min
 • Eurovia (France)
 • Zeolite
    – Minerals that have a
      micro-porous structure
    – Biggest use: detergent
 • Aspha-Min
    – Synthetic zeolite
    – Crystalline hydrated
      aluminum silicates
 • 21% moisture in pores
 • When heated the water
   foams the asphalt
    – Moisture  lubrication
 • Add to mix
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Aspha-min Zeolite
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Advera
                                       • PQ Corporation
                                       • Zeolite
                                       • Advera
                                              – Synthetic zeolite
                                              – Crystalline hydrated
                                                aluminum silicates
                                       • 18-21% moisture in pores
                                       • When heated the water foams
                                         the asphalt
                                              – Moisture  lubrication
                                       • Add to mix
                                              – 0.25% by weight of mix
                                                (5 lbs per ton)




                             Pictures from a presentation by Annette Smith of the PQ Corporation
         (http://76.12.53.242/submissions/42_20071227_Annette%20Smith%20-%20Advera.ppt)
                                                CEE597 Pavement Construction & QC




Sasobit

 • Sasol International (RSA)
 • Fischer-Tropsch wax
    – From coal gassification
    – Melts at 216-221°F
    – Long chain aliphatic carbon
      (40-120 carbons)
 • Melted sasobit = lubrication
                                    picture from GraniteRock
 • Add to binder or mix
                                                                                          CEE597 Pavement Construction & QC




Sasobit: Effect on Binder Viscosity
                                                                                                    0.35

                             1000

                                                                                                    0.3




                                                                                                           Viscosity at 135 °C [Pas]
   Viscosity at 60°C [Pas]




                              800


                                                                                                    0.25
                              600


                                                                                                    0.2
                              400



                              200                                                                   0.15
                                                                       Viscosity at 60°C
                                                                       Viscosity at 135°C
                                0                                                                   0.1
                                    0           1              2             3                  4
                                        Fischer - Tropsch Hard Wax in Pen 70/100 [wt.%]

                                                              From Prem Naidoo Sasol Wax Presentation
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Evotherm

  • MeadWestvaco
  • Asphalt emulsion
       – Added at 5% of asphalt
         content
       – It is 85% water and 15%
         chemical package
  • Capable of very low
    mix/compaction
    temperatures (140°F)
  • Need more
    Evotherm/ton of mix
    than asphalt binder
    because of 70%
    emulsion
Pictures from MeadWestvaco website
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                               WMA Costs
                 WAM Foam             Aspha-min            Sasobit           Evotherm
Equipment          $30,000-           $0-$40,000         $0-$40,000            minimal
modification       $70,000
Royalties or    $15,000 1st yr         $0.60/lb            $0.80/lb            7-10%
material        $5,000/plant/yr                                               more than
                   $0.30/ton                                                   binder

Cost/ton           $0.30 *               $3.60          $1.30–$2.60         $3.50-$4.00



    * Not including installation cost and royalty




     Note: the market for WMA is still developing. Producers are still working to
     establish their price point. Prices will change and likely go down in the future
                                         CEE597 Pavement Construction & QC




WMA Benefits: Emissions

• Importance depends on environmental situation
• Direct benefit to the producer is necessary

• In USA:
  – Economic or regulatory incentives to reduce
    emissions exists but is limited
  – Plants can generally meet BACT without WMA
• In Iceland:
  – Incentive to adopt WMA remains low until emission
    limits are lowered
Map from the EPA Green Book Nonattainment Areas for Criteria Polluntants
(http://www.epa.gov/air/oaqps/greenbk/mapnpoll.html)
                                     CEE597 Pavement Construction & QC




Benefits: Energy Consumption

 • Importance depends on the type and
   cost of energy

 • Where fuel is expensive energy savings
   could offset WMA cost
   – Otherwise, the cost of WMA is greater than
     the energy savings
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                        WMA Savings
                          Iceland        Honolulu, HI        Joliet, IL

Fuel source             No. 2 Fuel oil       Diesel         Natural gas
Fuel to make 1 ton
                         2-3 gallons      2-3 gallons      2.5-3.5 therms
of HMA
Fuel Cost                $2.50/gal       $2.20-3.20/gal   $0.70-0.80/therm
Fuel Cost to make
                        $5.00-$7.50       $4.40-$9.00       $1.75-$2.80
1 ton of HMA
Electricity to make
                         8-14 kWh          8-14 kWh          8-14 kWh
1 ton of HMA
Electricity Cost         $0.02/kWh       $0.1805/kWh       $0.0445/kWh
Average energy
                        $5.15-$7.78      $5.84-$11.53       $2.11-$3.44
cost for 1 ton of HMA
20% savings with WMA    $1.00-$1.50       $0.88-$1.80       $0.35-$0.56
50% savings with WMA    $2.50-$3.75       $2.20-$4.50       $0.88-$1.40
                                  CEE597 Pavement Construction & QC




Benefits: Lower Viscosity

 • Research and marketing has focused on
   the environmental benefits

 • Cost of compaction risks can far
   outweigh WMA costs

 • Viscosity reduction may provide the best
   business case for WMA
                                            CEE597 Pavement Construction & QC




Benefits: Lower Viscosity

 • Improved workability
   – A higher quality construction
 • More compaction per roller pass
   – Fewer roller passes needed
 • More workability/compaction for stiff mixes
   – More quality for mixes with high RAP content
 • Better compaction at lower temperatures
   – Cold weather paving
   – Increased haul distances
   – Extended paving season in cold areas
                                                                                                    CEE597 Pavement Construction & QC




Sasobit: Compaction Effects
                      3.0% addition by weight of binder (1.5% is more common)
                      160                                                                                      2,350
                                150

                      140                                                    2,285
                                                                                                               2,300
                                      130                             2,28
 Temperature [ °C ]




                                                           2,27                       2,27
                                                                                               2,26
                      120                                                                                      2,250




                                                                                                                     Density [ g/ cm³ ]
                                                 2,23

                      100                                                                                      2,200
                                                 85
                                                           79     78
                      80              2,15
                                                                                 70
                                                                                                               2,150
                                                                                          66
                                                                                               60
                      60                                                                                       2,100

                      40                                                                                       2,050

                      20                                                                                       2,000
                            1,975

                       0                                                                                       1,950
                            0         1      2            3       4          5        6        7           8
                                                        Number of rolling cycles
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Reduced Compaction Temperature




HMA – no Sasobit




                   WMA – 1.5% Sasobit by weight of binder
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Cold Weather Paving
    (37°F and windy)
Maryland SHA: Sasobit + 35% RAP mix
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Maryland SHA: High RAP Sasobit

 • 35% RAP by weight of aggregate
 • Compaction temperature = 270°F
 • Mat characteristics
   – Crew reported good workability
   – More compaction per roller pass
   – 92.6% Rice density with Sasobit
                                                                               CEE597 Pavement Construction & QC




RAP and Sasobit

Material Costs                                           Other Costs
                        Unit Cost        Tons    Cost                       Unit Cost      Tons         Cost
Milling Operation                                        Plant Operations
Milling cost                $0.00        1.00    $0.00   Energy cost           $4.00        1.00      $4.00
Trucking                    $5.00        1.00    $5.00   Overhead              $7.00        1.00      $7.00
RAP cost                                         $5.00   Plant cost                                  $11.00

Virgin Materials                                         Trucking
Virgin aggregate          $15.00         0.95   $14.25   Trucking              $5.00        1.00       $5.00
Asphalt binder           $400.00         0.05   $20.00   Trucking cost                                 $5.00
Virign materials cost                           $34.25
                                                         Placement
Assumptions                                              Crew                  $5.00        1.00      $5.00
1. Trucking at $80/hr, 1 hr cycle time                   Equipment             $5.00        1.00      $5.00
2. milling cost included in job bid                      Placement cost                              $10.00

                                                         Total other cost                            $26.00
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RAP and Sasobit
        RAP        Virgin      Material         Other          Total
     Content      Content       Costs          Costs           Cost
         0%         100%        $34.25         $26.00         $60.25
         5%          95%        $32.79         $26.00         $58.79
        10%          90%        $31.33         $26.00         $57.33
        15%          85%        $29.86         $26.00         $55.86
        20%          80%        $28.40         $26.00         $54.40
        25%          75%        $26.94         $26.00         $52.94
        30%          70%        $25.48         $26.00         $51.48
        35%          65%        $24.01         $26.00         $50.01
        40%          60%        $22.55         $26.00         $48.55
        45%          55%        $21.09         $26.00         $47.09
        50%          50%        $19.63         $26.00         $45.63

 Conclusions:
 1. Using RAP with WMA could offer competitive advantage for contractors.
 2. By changing the rules, agencies could lower the price of HMA.
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Grace Pacific: Multi-Lift Paving
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Testing and Demonstrations

 • 10 years experience
 • US and worldwide
 • Lift thicknesses
   – 1 to 3.5 inches
 • Minimum ambient temperature = 37°F
 • RAP content
   – 0 to 45%
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Risk…

 • WMA is a new technology
 • Long-term performance?
   – Oldest test sections are about 10 years old
   – Accelerated pavement testing
 • Uncertain use
   – Investment in equipment modification,
     materials and training
   – Commitment?
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Industry Concerns

 •   Baghouses
 •   Plant Modifications
 •   Available Binder Storage Tanks
 •   Changing Behaviors
 •   Changing Paving/Compaction Procedures
 •   Costs
 •   DOT Acceptance
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DOT Concerns

 •   Costs
 •   Testing
 •   Long-Term Performance
 •   AASHTO Provisional Standard
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What is Next?

 •   Determine long-term performance
 •   Life cycle analysis
 •   Commitment to use by owner agencies
 •   Contractor expertise
 •   Price point from WMA producers

								
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