Warm Mix Asphalt and Pavement Sustainability: A Review
Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the development and deployment of warm mix asphalt technologies. Such technologies make it possible to produce and place asphalt concrete at reduced temperatures compared to conventional hot mix methods. Several studies have reported on the potential of warm mix asphalt with regard to improved pavement performance, efficiency and environmental stewardship. This paper reviews several of those studies in the context of pavement sustainability. Overall, warm mix asphalt provides substantial sustainability benefits similar to or, in some cases, better than conventional hot mix asphalt. Sustainability benefits include lower energy use, reduced emissions, and potential for increased reclaimed asphalt pavement usage. Growth in utilization of warm mix asphalt worldwide may, in the not too distant future, make the material the standard for asphalt paving. Regardless, there are concerns over some aspects of warm mix asphalt such as lower resistance to fatigue cracking, rutting and potential water susceptibility problems, particularly with mixes prepared with water based technologies, which require further research to address.