Environmental benefits of warm mix asphalt technologies: Experience of the city of Calgary

Development of Sustainable pavement infrastructure development with environmentally friendly alternatives is preferred to reduce greenhouse gas emissions. Warm mix asphalt (WMA) is identified as one of the alternative to the typical hot mix asphalt (HMA) used on pavement construction to reduce these emissions. WMA technology allows an asphalt mix to be prepared and placed at lower temperatures than conventional hot mix. This study is focused on a comparative study of three WMA mixes and a HMA control mix used in the construction of an environmentally focused subdivision in the City of Calgary, Alberta, Canada. The scope of the study covers aspects related to asphalt plant production, asphalt plant emissions, construction, laboratory performance, and initial road performance with different WMA technologies in comparison to HMA. Paper reports on the findings related to the asphalt plant production, asphalt plant emissions, and construction stage of the study. The advantages of using WMA technology were evidenced during the mix manufacturing and road construction stages. The WMA mixes showed reduced emissions, lower fuel consumption, reduced smoke and odors, improved safety and working environment, improved mix workability, extended compaction time, more uniform compaction, and reduced thermal segregation. The laboratory evaluation showed that the WMA mixes behaved similar or superior to the HMA mixes. WMA mixes had similar rutting and fatigue resistance, better low temperature behavior, higher laboratory workability, and similar stripping susceptibility, than the conventional HMA mixes. However WMA mixes showed slightly lower mix stiffness at high temperature compared to HMA mixes.