Material design and performance improvement of conductive asphalt concrete incorporating carbon fiber and iron tailings

Abstract

The key challenge with the design of conductive asphalt concrete lies in optimizing the balance between electrical and mechanical properties for critical performance evaluation. This study concentrates on the material design and performance improvement of conductive asphalt concrete, which exploits the intrinsic conductive behavior of carbon fiber (CF) as a smart structural material in addition to iron tailings aggregates (TA). TA is introduced as a partial substitute of natural aggregates (NA), to provide continuous conductive structural contacts throughout the mixture for improvement in electrical and mechanical performance. To achieve this goal, first TA and NA were analyzed for chemical and phase compositions. The characterization manifested that TA exhibits a complex composition consisting of different species of iron. Secondly, a materially optimized conductive mix composition was developed in terms of the balance between electrical and mechanical properties. The results indicated that the addition of 0.2%–0.4% CF by weight to the mixture concludes optimum conductive mixtures for critical performance evaluation. Moreover, it was revealed that the addition of CF with TA significantly improves the electrical and mechanical properties of mixtures. Thirdly, electromechanical testing was conducted to explore the resistance change response of optimum conductive mixtures against changes in composition (deformation) induced as a result of mechanical loading. The results indicated that resistance change response to mechanical loading depends on the mix composition, type of loading and geometry of the test specimen. The reversible and smooth variation in resistance shows a mix with good structural integrity and its ability to heal deformation during unloading. By contrast, the irreversible and discontinuous variation in resistance is referred to as the damaging of the conductive network and eventually the structural failure. The mix incorporating 0.4% CF and TA as a partial substitute of NA serves as a smart composition since it retains satisfactory mechanical strength and responds to minor and reversible effects during mechanical loading.