Environmental Impact Comparison Analysis between a Traditional Hot Mixed Asphalt (HMA) and with the Addition of Recycled Post-Consumer Polyethylene Terephthalate (RPET) through the Life Cycle Assessment (LCA) Methodology

Abstract

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 an internal normalization criteria and weighting rule, obtaining an environmental score for each alternative and allowing an easy 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 functional units, the HMA + RPET pavement structures (FU 2 and FU 3) resulted in lower environmental scores (ES) with 49.2 and 47.1, respectively, representing a difference of 26.9 and 29 score points in comparison to the conventional pavement structure (FU 1 − C), with an ES of 76.1. It represents 38% of environmental savings in terms of the environmental score in favor of sustainable pavement alternatives. Focusing on the impact in global warming potential, the use of RPET in the HMA mixes for pavement design can result in savings up to 47.44% of impact decrease (20.4 ES) in comparison with the conventional-mix pavement structure proposal. This result supports the environmental sustainability of the HMA + RPET mixes and is a precedent for future research on new geotechnical and pavement alternative materials.