Mechanical, carbon emissions, and cost assessment of asphalt mixtures with incorporation of waste solar panel

Asphalt production consumes substantial amounts of raw materials and energy, while the growing volume of end-of-life solar panels globally creates a significant landfill challenge. This study evaluates the feasibility of repurposing waste solar panel (WSP) powder as a filler in asphalt concrete, addressing both the need to reduce solid waste and to conserve natural resources. The effects of WSP powder on mechanical performance of asphalt mixtures have not been previously studied. In this study, first, Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) analyses were performed to examine elemental compositions and morphology of WSP powder. Next, to assess the mechanical characteristics, asphalt mixtures made with 30 % and 100 % WSP replacement for filler were tested using Indirect Tensile Stiffness Modulus (ITSM), Indirect Tensile Fatigue Test (ITFT), Indirect Tensile Strength (ITS), and Tensile Strength Ratio (TSR). Results showed that incorporating WSP improves the stiffness and fatigue resistance by up to 33 % and 68 %, respectively, compared to the control mixture, while reducing moisture resistance by up to 8.5 %. Carbon emissions, energy consumption, and production costs per ton were also analysed. Two multi-criteria ranking methods were implemented to integrate mechanical performance and environmental factors into a single index for ranking mixtures. Although the mix with 100 % WSP (WSP100) increased carbon emissions by 13.8 %, it reduced energy consumption by 6.2 %. WSP30 showed comparable emissions to the control while reducing energy use by 5.5 %. Higher emissions reflect the inclusion of recycling process-related impacts, which may be lower in practice if WSP is sourced ready-to-use. The assessment did not account for reduced pavement maintenance following improved performance, which could significantly lower environmental impacts. Ranking results indicate that WSP mixtures achieve higher index values than the control, with the mixture containing 30 % WSP outperforming the 100 % WSP mixture. Overall, the findings indicate that WSP could be a suitable filler replacement in asphalt production, provided that its optimum content is determined. • Waste solar panel was evaluated as an effective filler replacement in asphalt mixture. • Waste solar panel improved stiffness and fatigue life of asphalt mixtures. • Moisture resistance decreased with the addition of waste solar panel filler. • Carbon emission and costs were assessed for asphalt mixtures containing solar panel.