Warm Mix Technology The Canadian Perspective J.Keith Davidson P.Eng. McAsphalt Industries Limited...
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Transcript of Warm Mix Technology The Canadian Perspective J.Keith Davidson P.Eng. McAsphalt Industries Limited...
Warm Mix TechnologyThe Canadian Perspective
J.Keith Davidson P.Eng.McAsphalt Industries Limited
Toronto Ontario Canada
CUPGA – 2007 – Niagara Falls
Background
• Kyoto Accord
• Energy prices increasing
• Stricter environmental rules
• Emission reductions
Introduction
• 6 main processes
– Aspha-min– Sasobit– Wam Foam– Low Energy asphalt– Astec Process– Evotherm
Aspha-min Process
– Eurovia of Germany– Synthetic zeolite (Sodium Aluminum Silicate)– 21% water/ white powder– Added to mix at same time as binder– Water spray created slowly which foams binder– Gives increased workability and allows coating at
lower temperature– Typically 0.3% added to mix– Temperature drops up to 30 - 35°C
Sasobit Process
– Sasol of South Africa– Paraffin wax made from Fischer-Tropsch process– Different cystalline structure compared to
conventional waxes– Melts into binder at 110°C– Reduces viscosity of binder– Temperature reductions of 10 to 40°C– Typically 1 - 2% added to binder– Improves rutting resistance
Wam Foam Process
– Shell has operates the process– 2 binder component system– Soft binder and a foamed harder bitumen– Soft binder mixed at 110°C– full coating– Hard binder foamed into soft binder coated
particles– Blend of hard and soft binder critical to process
Low Energy Asphalt Process
• Coarse aggregate heated and coated• Fine aggregate added at ambient temperature• Additives added to AC• Foaming action creates lower temperatures• Maintains workability and compaction• 100°C laydown temperatures typical
Astec Process
• Foaming kit on double barrel drum plant• 10 nozzle system (individually controlled)• Up to 500 tph (50 tph/nozzle)• 550 US gal water system (skid mounted)• Reduction in energy usage
• Mixing temperature reductions of 30°C
Evotherm Process
– Non-proprietary technology based on a chemical package
– Additives to improve coating, workability, adhesion and emulsification
– Two methods of production• A high residue emulsion (67-69% PGAC)• DAT Concentrate (Dispersed Asphalt
Technology)– Injection system
Process Trials
• 5 Processes in Canada being evaluated• Aspha-min• Sasobit• Wam Foam• Astec Process• Evotherm
Aspha-min
• Trials placed in 2005 & 2006
• Construction DJL has been the contractor
• Working with Eurovia
• Various PG grades used
Sasobit
• In its infancy here• Bitumar (AC Supplier)• Working with Sasobit Consultant• 2 trials
– City of Toronto – 300t– City of Ottawa – 3000t
Wam Foam
• 1 trial in City of Calgary – 2005• LaFarge retrofitted a plant to produce• Placed in August in new subdivision
– Covered with surface mix– Performed well
• Mixing and compaction temperatures lowered significantly
ASTEC Process
• 5 trials this year• New plant (double barrel green)• Can retrofit existing drum plants• Energy reductions (10-15%)• Emissions reduction• Compaction temperatures 100°C
range
Evotherm
• 3 trials in 2005 – 1700 tonnes• 1 Trial in 2006 – 1250 tonnes• 7 Trials in 2007 – 9200 tonnes• Various PG grades used
Evotherm DAT Process
• Concentrated solution of Evotherm
• Pumped, metered & injection system
• Injected into pugmill as AC is added
• Chemical into AC
• Creates foaming and disperses chemical
Environmental Data – Warm Mix
• Definite reductions in Greenhouse gases– reductions up to 60%
• Reductions in fuel usage– 10 – 50% reduction
• Reduction in fumes at paver– Up to 50%
Other Benefits of Warm Mix
• No mix design issues (Marshall or SuperPave or Hveem)
• Physical properties equivalent to HMA
• Performance properties equivalent to HMA
• Reduced age hardening through plant
• Longer haul distances
• Excellent compaction
The Future
• Tendering of projects
• Continued expansion of usage of warm mix
• High RAP mixes
Way of the future in our industry