Mechanical Performance and Low-Carbon Sustainability of Cement-Stabilized Macadam with Recycled Plastic Aggregate

Against the background of the global “dual carbon” strategic goal, low-carbon upgrading of road engineering and efficient recycling of waste plastics have become critical approaches to relieve the shortage of natural aggregates and control plastic pollution. Most existing studies only focus on the optimization of single mechanical indicators, while lacking collaborative analysis of mechanical performances and carbon reduction benefits, meaning they cannot provide sufficient scientific support for the design of low-carbon and sustainable road materials. In this study, recycled plastic aggregate (PA) was used to partially replace natural coarse aggregate, and its influence on the mechanical characteristics of cement-stabilized macadam (CSM) was systematically investigated. Combined with life cycle assessment (LCA), the carbon emission reduction potential was quantitatively evaluated, aiming to improve the toughness of road base materials and promote low-carbon sustainable development. The results demonstrate that when the PA content increases from 0% to 20%, the mechanical strength of CSM gradually decreases, while the toughness presents a steady upward trend, and the maximum carbon emission reduction rate reaches 50.8%. The optimal toughness improvement of 28.39% is obtained at the PA content of 16%. This study clarifies the internal correlation between mechanical behaviors and low-carbon benefits of recycled plastic aggregate, provides reliable technical support for the high-value utilization of waste plastics and the optimization of sustainable road materials, and offers important references for the green and low-carbon transformation of transportation infrastructure.