Development of self-sensing asphalt cementitious composites using conductive carbon fibre and recycled copper tailing

Abstract

Disposal of the highly hazardous and large scale solid wastes such as tailings is a global challenge. To mitigate the heavy burden of tailings management while promoting the circular economy, this study combines smart material with tailings recycling, presenting a pioneering investigation into the reutilizing copper tailings (CT) as an alternative to limestone filler (LF) for the development of sustainable carbon fibre (CF)-based self-sensing asphalt concrete. The conductivity, percolation zone, impedance spectroscopy, self-sensing performance, porosity distribution, immobilization of toxic metals, road performance, and cost-benefit analysis were comprehensively examined. The results indicate the incorporating CT enhances high-temperature resistance but reduces low-temperature cracking resistance and increases moisture susceptibility of asphalt concrete when CT substation exceeds 50 %. However, substituting up to 50 % LF with CT meets the road performance criteria. Percolation is observed at approximately 0.1 % – 0.3 % CF for CT/CF asphalt concrete. A novel conductive path-based equivalent circuit model is established based on impedance spectra by separately allocating circuit elements to conductive phases, which is validated by the correlative analysis of variations in equivalent circuit elements and their alignments to percolation theory and the results of conductivity and piezoresistivity. This contributes to the understanding of conductive and sensing mechanisms of CF-based self-sensing asphalt concrete. The findings will advance smart road technology while promote mine waste reutilization for enhanced traffic detection and structural health monitoring.