AAPA 2010 Study Tour – Warm Mix Asphalt Warm Mix Asphalt Warren Carter | Cassandra Simpson Andrew Bethune

AAPA 2010 Study Tour – Warm Mix Asphalt Introduction 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

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 HMA Temp = 160 oC WMA Temp = 132 oC

AAPA 2010 Study Tour – Warm Mix Asphalt Warm MixHot 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 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) o Market: 2% (2007) – 10% (2010) – 50% (2015?) Key properties being evaluated o Deformation resistance/rutting o Cracking/fatigue o Moisture sensitivity

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 differently o collaborative trials o permissive specifications o lengthy approval processes with laboratory and field evaluation o list of approved technologies/products o 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 MixHot Mix

AAPA 2010 Study Tour – Warm Mix Asphalt Questions?