Upload
archibald-abner-douglas
View
220
Download
4
Tags:
Embed Size (px)
Citation preview
AAPA 2010 Study Tour – Warm Mix Asphalt
Warm Mix Asphalt
Warren Carter | Cassandra SimpsonAndrew Bethune
AAPA 2010 Study Tour – Warm Mix Asphalt
IntroductionIntroduction
• WMA represents a group of technologies which allow a reduction in the temperatures at which asphalt mixes are produced and placed
• WMA is produced at temperatures that are 20°C - 50°C below that of hot mix
www.aapa.asn.au
AAPA 2010 Study Tour – Warm Mix Asphalt
Emissions and Energy
AAPA 2010 Study Tour – Warm Mix Asphalt
Benefits of WMA• Improved working conditions• Less fumes and emissions• Less energy consumption• Decreased binder aging during production• Early site opening• Cool weather paving• Compaction aid for stiff mixes• Longer haul distances• Improved and more consistent compaction
AAPA 2010 Study Tour – Warm Mix Asphalt
HMATemp = 160oC
WMATemp = 132oC
AAPA 2010 Study Tour – Warm Mix Asphalt
Warm Mix Hot Mix
AAPA 2010 Study Tour – Warm Mix Asphalt
WMA Technologies
• Free water systems (mechanical foaming by water injection) – 130°C - 140°C
• Water carrying chemical additives (additives introduce moisture e.g. synthetic zeolites) – 115°C - 135°C
• Water carrying non-chemical additives (LEA process) – 95°C - 110°C
• Chemical additives (reduce internal friction e.g. Cecabase RT, Evotherm 3G, HyperTherm, etc) – 110°C - 135°C
• Rheological modifiers (reduce binder viscosity during mixing e.g. Sasobit, Rediset WMX, etc ) – 115°C - 135°C
AAPA 2010 Study Tour – Warm Mix Asphalt
WMA Production TemperaturesWMA Production Temperatures
AAPA 2010 Study Tour – Warm Mix Asphalt
WMA Technologies
AAPA 2010 Study Tour – Warm Mix Asphalt
US Experience - Evaluation
• European scan/study tours (2002 and 2007)• Growth has been rapid
o Technologies: 3 (2005) – 23 (2010)o Trials: 15 states (2007) - 45 states (2010)oMarket: 2% (2007) – 10% (2010) – 50% (2015?)
• Key properties being evaluatedo Deformation resistance/ruttingo Cracking/fatigueoMoisture sensitivity
AAPA 2010 Study Tour – Warm Mix Asphalt
Warm Mix Demonstration Projects in the U.S. as of Jan. 2007
Warm Mix Demos
AAPA 2010 Study Tour – Warm Mix Asphalt
Warm Mix Demonstration Projects in the U.S.
Warm Mix Demos
AAPA 2010 Study Tour – Warm Mix Asphalt
US Experience - Implementation
• Initial client desires were that WMA provides equal or better performance compared to hotmix
• The various states have approached implementation differentlyo collaborative trials o permissive specifications o lengthy approval processes with laboratory and field
evaluationo list of approved technologies/productso maximum production temperatures (non-attainment
areas, over crack sealing, etc)
AAPA 2010 Study Tour – Warm Mix Asphalt
US Experience - WMA
• Dense graded asphalt• Open graded asphalt• Stone mastic asphalt• Crumbed rubber asphalt• Conventional bitumens and polymer modified
binders
AAPA 2010 Study Tour – Warm Mix Asphalt
US Experience - Concerns
• Rutting• Strength issues• Stripping• Water injection technologies in freeze climates
(ravelling)• Production issues – ensuring the aggregate is
dry• Plant addition of WMA additives vs terminal
blending
AAPA 2010 Study Tour – Warm Mix Asphalt
US Experience – WMA Mix Designs
• Mix designs are generally the hotmix design with the warm mix technology applied
• Some minor allowance is made to WMA containing Advera and Asphamin as these become an inert filler (once the water is remove)
• Lower voids of a WMA mix design compared to the hotmix design (but binder content isn’t adjusted)
AAPA 2010 Study Tour – Warm Mix Asphalt
Warm Mix Hot Mix
AAPA 2010 Study Tour – Warm Mix Asphalt
Questions?