Life cycle assessment of incorporating recycled materials in pavement design

This study was set out to conduct a life cycle assessment (LCA) to explore the environmental and economic impacts of pavement design alternatives using reclaimed asphalt pavement (RAP) and recycled plastic. 25 design alternative pavement designs were considered for a four-lane 8 km-long highway section. Design mix percentages varied between 0 and 40% of RAP with 10% increments and 0–20% of recycled plastic with 5% increments. The impact was assessed based on estimating utilized energy and water resources, climate change impact in terms of CO₂ equivalent, and air pollution in terms of air acidification, human health particulate (HHP), and photochemical smog. Results show that recycled plastic is superior to RAP in reducing energy consumption and GHG emissions. Both RAP and recycled plastic reduced water consumption. Recycled plastic reduced air acidification, HHP, and smog. RAP also increased HHP substantially, mainly during materials production. It was found that the RAP replacement ratio of 10% yielded the highest value of energy consumption, harmful gases emissions, air acidification, HHP, and Smog. RAP and plastic both reduced costs substantially as recycled material reduced the use of virgin materials and bitumen. In addition, using RAP eliminates the cost of moving RAP to landfills.