Electrically conductive hot mix asphalt mixtures for salt-free snow/ice-melting pavements heated with direct electric energy: A comparison between utilizing carbon-based aggregate and fiber

The accumulated snow/ice on the asphalt pavement in winter causes a great threat to traffic safety. Traditional approaches such as employing mechanical equipment and deicing chemicals usually can damage pavements and pollute the environment. Constructing the asphalt pavement using electrically conductive hot mix asphalt mixtures (ECAM) to melt snow and ice with direct electric energy is an environmentally friendly method. Carbon fiber has been reported by previous studies as a common electrically conductive additive to make asphalt binder conductive to fabricate ECAM. In this study, a coal-derived solid carbon lightweight material called coke aggregate was utilized to partially substitute for the nonconductive traditional mineral aggregate to make a new type of ECAM for salt-free snow/ice-melting pavements. The electrical conductivity, mechanical properties, heating efficiency at a low temperature of −10 °C, and material costs of the proposed ECAM made with coke aggregate were comprehensively investigated and compared with the ECAM utilizing carbon fiber. The results indicated that there existed an optimal content of coke aggregate and carbon fiber to achieve the desired electrical conductivity, which was 38 vol% (by volume of aggregate) and 1 vol% (by volume of mixture) respectively in this study. Both types of ECAM had satisfactory resistance to rutting, fatigue cracking, and moisture damage, which were suitable for practical application. In addition, although both ECAMs had a comparable electrical resistivity at room temperature (22 ± 2 °C), the ECAM made with 38 vol% coke aggregate had around 40% higher heating efficiency at −10 °C and 41% lower material costs than the ECAM made with 1 vol% carbon fiber. Thus, it is promising to utilize coke aggregate to make ECAM for pavement snow-melting and deicing applications.