Life cycle assessment of low temperature asphalt mixtures for road pavement surfaces: A comparative analysis

The increasing fuel consumption demand, the accelerated pressure imposed by the depletion of scarce raw materials and the urgent environmental protection requirements are forcing the change of pavement industry and academia community's research endeavours towards the development of low emissions road paving technologies able to significantly reduce mixing and compaction temperature as well as the consumption of virgin raw materials. One of the relatively recent technologies in the field of pavement materials that aims at addressing those concerns is the incorporation of reclaimed asphalt pavement (RAP) in the production of warm mix asphalt (WMA). It is within this context that this study presents a full process-based comparative life cycle assessment (LCA) looking at understanding the environmental impact of reducing mixing temperature, through the use of warm mix technologies, namely chemical additives-based and foamed-based, and different rate of recycling (0% and 50% RAP). Furthermore, the investigation explores the effect of combining these technologies in the construction, maintenance and rehabilitation (M&R) of wearing courses for flexible road pavements. The results of this study showed that, for the conditions considered and assumptions performed, a pavement construction and M&R scenario in which a foamed-based WMA mixture with a RAP content of 50% is employed in the wearing course throughout the pavement life cycle is the most environmentally friendly alternative among all the competing solutions.