Life cycle assessment of energy consumption and carbon emissions of a green maintenance material for asphalt pavement: Warm mix OUFC-5

The warm mix (WM) 4.75 mm nominal maximum aggregate size (NMAS) Open-Graded Ultra-thin Friction Course (WM OUFC-5) represents an innovative green preventive maintenance material boasting commendable road performance. Its potential to address carbon peak and neutrality goals objectives has garnered significant interest. This study aims to quantify the energy-saving and carbon reduction benefits of WM OUFC-5. Three commonly used preventive maintenance materials, including thin overlay (TO), synchronous surface dressing (SSD), and micro-surfacing (MS) in Hubei province, China, were selected as a control group. Employing the process-based life cycle assessment (PLCA), an evaluation framework and computational model was devised to gauge the energy and carbon footprints of each maintenance material. A comparative analysis was then conducted to identify the primary energy and emission contributors of WM OUFC-5 across different life-cycle phases. The results indicate that WM OUFC-5 is a highly sustainable material with low energy consumption and carbon emissions, with its energy consumption being merely 47.2% of TO and 50.7% of MS. And its carbon emissions are 64.3% lower than TO, 26.9% lower than MS, and 49.8% lower than SSD. Throughout the maintenance life cycle, the raw materials production and processing phase and the mixture production phase emerged as the predominant contributors to energy consumption and carbon emissions. The study also provided actionable recommendations to curtail energy and carbon footprints across all phases of the asphalt pavement maintenance life cycle. This study provides support for the low-carbon development of asphalt pavement maintenance in China.