Developing highly conductive asphalt concrete by incorporating stainless steel fibers/wires for smart pavement

Endowing asphalt concrete with stable conductive properties is beneficial to develop smart pavement such as self-sensing, self-healing, self-deicing and snow-melting pavement, thus improving the service life and realizing the sustainable development of pavement. In this paper, the conductive properties and mechanisms of high anti-corrosion stainless steel wires (SSWs, with a diameter of 20 μm) and stainless steel fibers (SSFs, with a diameter of 0.2 mm) modified asphalt concrete fabricated by different mixing methods were investigated. Experimental results show that incorporating 1 vol% SSWs firstly with asphalt and mineral powder can reduce the direct current (DC) resistivity of asphalt concrete to 18.54 Ω·m and make alternate current resistivity independent of voltage frequency, while the DC resistivity of asphalt concrete with 24 vol% SSFs (firstly mixing SSFs with aggregates) is still as high as 104–106 Ω·m. The equivalent circuit obtained by electrochemical impedance spectroscopy and the conductivity calculated by general effective media equation illustrates that the conductive elements in SSFs modified asphalt concrete are mostly interface capacitors between SSFs, while low content of SSWs have overlapped to form the stable conductive path in asphalt concrete, resulting from the micro diameter, high aspect ratio, and high flexibility of SSWs.