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Explore the concept, history, and environmental advantages of using WAM Foam in asphalt pavements at lower temperatures. Learn about the reduction in emissions, improved production efficiency, and adherence to specifications. Discover the US perspective on WAM Foam adoption and the challenges faced in implementation.
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WAM Foam:asphalt pavements at lower temperatures WMA TWG, 12 December 2007, Hunt Valley - MD
WAM Foam • Basic Concept & History • Field Experience • Emission Reduction • US Perspective
Basic Concept Hard asphalt component PG 64-22 Soft asphalt component Viscosity Pa.s 100000 10000 1000 100 10 1 0.5 0.2 0.1 300 210 -60 32 120 390 480 25 50 75 0 ° F Temperature
Schematics of the typical process conditions TRADITIONAL HOT MIX ASPHALT 5% FILLER 20 OC 90% AGGREGATE DRYER SILO LAYING MIXER 270-320 OF 300-350 OF 320 OF 390 OF 6% ASPHALT WAM Foam ASPHALT MIX PROCESS 5% FILLER 20 OC 90% AGGREGATE DRYER MIXER SILO LAYING 260 OF 180-220 OF 225 OF 175-200 OF 1.8 % SOFT 4.2 % HARD COMPONENT
May 1999 DG 11 PG 52-28 (180/220) 1st WAM Foam 1999 (Norway)
WAM Foam after two years June 2001
WAM Foam installation in Hot Mix Asphalt plant 2000 Original asphalt line foam mixer New, 2nd asphalt line
Aggregate > 4 mm Soft Bitumen Aggregates 0-4 mm Hard Bitumen Foam Filler Discharge Batch Plant Mixing Cycle – 3.5 ton batch 5 15 25 Time (s) 0 55 35 Mixing Mixing -
Field trials RV 120 September 2000 WAM Foam, DG 11, PG58-22 (80 pen) May 2002 Reference, DG 11, PG58-22 (80 pen) May 2002
3.2 mm/year 2.9 mm/år WAM Abg 11 Rut development on RV 120
WAM Foam SMA 11, Track-paving on E6 - June 2002 Daily traffic 22000 vehicles - 65,2 kg/m2
Asphalt Fume Emission monitoring Emission measurements Source: Koenders et al, IRF 2004
Emission reduction Hot MixWAM Foam Fume emissionmeasurement PLEASE NOTE: Today typical Occupational Exposure Limits in Europe and US are TPM – 5 mg/m3 In this example Hot Mix emissions are still 4 times lower than OE limit !! TPM BSM Source: Koenders et al, IRF 2004 TPM = Total Particulate Matter BSM = Benzene Soluble Matter
54 % reduction Dust emission during actual Production Production process
Illustrations 230 F 311 F
230 F 329 F Illustrations HMA vs. WAM Foam
What has been we achieved with WAM Foam? • 30 % reduction in energy consumption, lower production costs • 30 % reduction in CO2-emissions, a gain for the environment! • 50 – 60 % reduction in dust emission, again a gain for the environment • Fume from WAM Foam is below detection limits,Health & Safety! • Reduced temperature => reduced oxidation/ageing of binder • WAM Foam satisfies all Hot Mix Asphalt specifications according to Handbook 018 (Norwegian Standard) • Production Capacity maintained
US Perspective • Binder components now available in the US • Final binders: PG 70-22, PG 64-22, PG 58-28 • Laboratory • 2007 mixing trials at Turner Fairbank / FHWA • 2007 evaluation at NCAT • Included in study Industry tour 2007 • Further US field verification 2008 • Mid West • Expand to modified grades ?
US Perspective Positives (when compared to other WMA): • No Additives, no expensive snake oils – “just add water” • Pre-coats Coarse Aggregate • Absorptive Aggregates Challenges: • Paradigm Shift • Asphalt Plant Binder Blending • PG Binder Grading system • Performance Acceptance Projects • Mix Design-Lab Foaming device • Asphalt Plant Modifications