LCA of production of warm mix asphalt: Slovenian experience

Construction of hot mix asphalt (HMA) pavements is associated with high environmental impact due to the consumption of large amounts of materials and energy. In recent years, warm mix asphalt (WMA) emerged as a more environmentally friendly alternative to HMA due to their potential to reduce both mixing and placement temperatures without conceding the performance and workability of asphalt mixture. Different technologies can be employed to reduce the working temperature in the production of WMA, e.g. the addition of organic or chemical additives, or the introduction of cold water into the hot asphalt mixture at a controlled temperature and pressure (i.e. foaming). However, it is often difficult to compare the environmental performance of different WMA technologies, as the environmental performance depends on specific characteristics of the production plant. This paper presents a comparative Life Cycle Assessment (LCA) analysis of the production of WMA with foaming with water and with the addition of chemical additive. LCA was based on real-case production data from a Slovenian asphalt production plant. The LCA results show that focusing only on CO2 emissions can be misleading, with reduction in CO2 emissions not necessarily leading to the reduction in the overall environmental impact.