Environmental Impact of Pavements with the Addition of Recycled Post-Consumer Polyethylene Terephthalate (RPET) through the Life Cycle Assessment (LCA) Methodology
life-cycle assessment (LCA); pavements; sustainability; recycled post-consumer polyethylene terephthalate (RPET); hot mix asphalt (HMA)
The present study presents a cradle-to-built life cycle assessment (LCA) for a road pavements structure of hot mixed asphalt (HMA) with recycled post-consumer polyethylene terephthalate (RPET) addition through the “dry” process using a comparison analysis between declared units equivalent of 1 ton of produced mix and functional units equivalent of 1 m2 pavement variants under the Brazilian “National Design Methodology” (MeDiNa), in contrast with a conventional mix variant. The Tool TRACI 2.0 for reducing and assessing chemical and other environmental impacts was applied for each alternative, assessing the impacts into categories such as acidification, eutrophication, freshwater ecotoxicity, global warming potential, human health, ozone depletion, and smog formation. The life-cycle impact assessment results were interpreted through internal normalization criteria and weighting rule, obtaining an environmental score for each alternative, and allowing a straightforward stakeholder interpretation. Considering the better mechanical properties and overall functional performance of the HMA + RPET mixes, the functional unit comparison on LCA methodology results in savings in all environmental impact categories for each square meter of pavement constructed and ready to use. For the declared unit comparison point, a conventional HMA mix presents better overall environmental performance and wastes than a HMA with RPET added in aggregate substitution through the “dry” process. Considering the better mechanical properties and overall functional performance of the HMA + RPET mixes for the surface course, the functional unit comparison resulted in savings in almost all environmental impact categories for each square meter of pavement constructed and ready to use, with an overall layer thickness optimization effect that carries a cascade of upstream resource and emissions savings. This effect was explored with the sensibility analysis of net PET mass added by FU (functional unit), with an equilibrium mass identified for global warming potential and environmental score, establishing the ground for sustainable pavement definition and delimitation. It establishes a novel sustainability criterion for pavement structures with the addition of plastic post-consumer, which integrates the mechanical and environmental performance and allows for guidance in future plastic-pavement research.