Warm Mix Asphalt
By: Pam McGowan
WMA Goals
• HMA quality
• Lower temperature
• Reduced emissions
How WMA Works
• Incorporates additives that reduce asphalt
viscosity
• Reducing viscosity means mixing at lower
temperatures
Types of Additives
• There are currently four types on the market
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Aspha-Min
WAM-Foam
Sasobit
Evotherm
Aspha-Min
WAM-Foam
• Product of Germany
• Synthetic zeolite crystals
• Internally held water
creates foam
• Uses 2 binders
• Soft binder coats
aggregate
• Water injected to create
foam
Sasobit
Evotherm
• Aliphatic hydrocarbon
produced from coal
gasification (long chain
wax)
• Reduces rutting
• Chemical mixture
• Creates emulsion
Benefits to WMA Technology
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Reduction of fuel expenses with lower heat
Increase in compaction results
Shorter binder curing time
Early site opening
Reduction in emissions
Tested and proven in Europe
Concerns with WMA
• Shorter aging time of asphalt could increase
rutting potential
• Plant modifications may be necessary
• Additives may increase moisture susceptibility