Enhancing Thermal Conductivity of Asphalt Pavements Using Carbon Nanomaterials: A Review

Asphalt pavements are crucial infrastructural elements for transportation networks, but their limited thermal conductivity poses challenges in dissipating excess heat, leading to premature deterioration and reduced lifespan. To address these issues, asphalt solar collectors have been proposed, where fluid-filled pipes embedded in the pavement transfer heat for various purposes, such as de-icing or heating buildings. Improving the thermal conductivity of asphalt becomes crucial to enhance the energy harvesting efficiency and heat transfer between the pavement surface and embedded pipes. This study explores the significant improvements in thermal conductivity and heat transfer efficiency of asphalt pavements achieved through the incorporation of carbon nanotubes (CNTs) and graphene (Gr). The review discusses the synthesis, chemical modification, and properties of CNTs and Gr, which are promising carbon nanomaterials due to their excellent thermal conductivity, corrosion resistance, and compatibility with asphalt. The research investigates various factors that positively influence thermal conductivity, including the volume or weight fraction of CNTs and Gr, CNT length, dispersion and alignment of CNTs, and axial thermal conductivity. Additionally, the effect of the number of carbon fiber bundles and the axial-radial thermal conductivity ratio on heat transfer efficiency is examined. The study also investigates the effects of different composite combinations. By utilizing these advancements, asphalt solar collectors can become more efficient in harvesting solar energy from the pavement surface, leading to sustainable and energy-efficient infrastructure solutions.