Life-Cycle Assessment of Asphalt Pavements with Recycled Post-Consumer Polyethylene

Abstract

Extensive amounts of plastic waste worldwide require viable methods of recycling and reuse. One such example is the use of recycled plastics (RP) in the asphalt pavement industry, which has massive material consumption and usage of polymer modifiers. Research studies on the use of RP in asphalt commonly identify environmental benefits as a key motivation. However, assessment of the environmental impacts of using RP is limited in the literature. To address this gap, this study presents a life-cycle assessment comparing asphalt pavement sections produced with RP with the alternatives made with conventional hot-mix asphalt (HMA) and polymer-modified asphalt. The assessed RP mixtures were made with recycled polyethylene pellets introduced via a dry process. Cradle-to-gate results indicated that the impact of RP mixtures was greater than HMA but less than a polymer-modified mix. To account for different mixture performance, the analysis was expanded to a functional unit of one lane-mile of pavement for cradle-to-built and cradle-to-grave scope. Changes in pavement thickness and maintenance intervals were analyzed to determine in which scenarios RP sections can present equal performance with HMA and polymer-modified alternatives. Results demonstrate that RP pavements are environmentally beneficial relative to HMA when savings in pavement thickness of 12.5% or extension of maintenance cycles by 7% are achieved. Relative to a polymer-modified alternative, RP sections present environmental benefits when equal performance is achieved with no changes in thickness or maintenance. Accordingly, the results of this study encourage the life-cycle thinking and bracket engineering performance needed to achieve environmental benefits.