Life cycle assessment (LCA) of using recycled plastic waste in road pavements: Theoretical modeling

Every year, considerable amounts of waste materials are produced and landfilled due to the construction, maintenance, and rehabilitation of road pavements. As a result, the road pavement sector is under increasing societal pressure to mitigate the negative environmental impacts arising from these construction and maintenance activities. Among other initiatives, the conversion of waste materials into alternative raw materials for road paving applications has been proposed to lower the extraction of virgin raw materials. As the market for recycled materials, including plastic recyclates, is becoming more complex, it is increasingly more difficult to quantify the potential environmental benefits of using these materials for road construction. A systematic appraisal method to assess the extent to which such practices are indeed environmentally beneficial is life cycle assessment (LCA). After presenting a condensed overview of the plastic waste management system and how plastic recyclates can be used in asphalt mixtures, this chapter offers an overview of the LCA methodology, including its main phases, elements, and modeling approaches. This is followed by a brief description of how the LCA methodology has been embraced by the pavement community, and the presentation of concepts, methodological, and operational aspects related to the application of LCA to waste management systems. A conceptual example of a consequential LCA case study is then presented to investigate the potential environmental consequences of utilizing plastic recyclates in place of virgin aggregates in the production of asphalt mixtures. This chapter then concludes with current challenges and open issues related to advanced LCA modeling aspects and opportunities for increasing the use of plastic recyclates in asphalt pavements. While the presented fundamentals of LCA modeling of recycled materials and pavements will be valuable for young researchers and practitioners, the explanation of consequential, and attributional LCA modeling approaches can provide interesting insights for advanced users.