Warm mix technology has become the latest buzz word in the area of asphalt technology. Worker health and safety, as well as environmental concerns have caused many people to look for different ways of producing asphalt concrete that maintains the physical properties and performance characteristics of traditional hot mix, but are more worker and environmentally friendly. This paper discusses the various warm mix asphalt processes being evaluated throughout North America. The paper will concentrate on the state of the practice within Canada. A more detailed review of projects carried out by McAsphalt Industries to study the effects of warm mix technology using the Evotherm® technology will also be discussed. The warm mix asphalt projects involved the placement of various types of asphalt mix on prepared granular base as well as overlays on existing asphalt pavements. The use of recycled asphalt pavement (RAP) will also be presented. Environmental testing has been performed on both the hot and warm mixes to monitor the greenhouse gases during production and these results will be discussed in detail. Based on the results achieved so far the warm mix asphalt technology provides lower emissions (greenhouse gases) than hot mix without compromising the performance properties of the mix; can be produced at hot mix plants with very little changes needed if any. Worker health and safety is being improved through the use of warm mix asphalt technology. Also, it has shown that less oxidation is occurring in the warm mix, which certainly will translate into longer service life. To this date there have been no major issues with any of the warm mix asphalt processes being used around the world.
