## 1 Introduction  
Asphalt concrete is a self-healing material which can close micro cracks during rest periods through bitumen flow and diffusion [1]. The potential benefits of applying self healing technology to asphalt pavements include reduced road maintenance with a subsequent reduction in CO\({}_{2}\) production, improved safety for both road users and road workers, improved road life span, and reduced cost of road maintenance [2]. However, the healing rate is quite slow due to limited bitumen flow at ambient temperatures. As a temperature sensitive material, the self-healing capacity of asphalt concrete can be enhanced by increasing the ability of wetting and diffusion of asphalt molecules through heating [3]. For this reason, an advanced self-healing technology named induction healing was developed to enhance the self-healing capacity of asphalt concrete through induction heating [4; 5; 6]. Steel fibers were added to the asphalt mixture to make it electrically conductive and induction heating was applied to increase the healing capacity of asphalt concrete when cracks occurred in asphalt mastic [7; 8; 9; 10]. During induction heating, the asphalt mastic containing steel fibers was heated very quickly while the mineral aggregates could not be heated [10]. In such a way, the cracks within asphalt mastic can be healed quickly without affecting the stone structure. It has been proven by many researchers that induction heating can restore the stiffness, strength and fatigue life and prevent the raveling and cracking of asphalt concrete efficiently without ageing asphalt binder due to very short heating time [10; 11; 12; 13; 14; 15; 16; 17; 18]. Therefore, induction healing is a promising maintenance technology for asphalt pavement, which can heal the microcracks and prevent them from developing into cracking, stone loss and potholes.  
However, the induction heating speed of asphalt mixture is limited. [PERSON] et al. prepared asphalt concrete by replacing mineral aggregates with steel slag and found that it can be heated at 11.6 \({}^{\circ}\)C/min with induction heating [11]. [PERSON] et al. prepared asphalt mixture by adding 4% steel shots and found that its induction heating speed is 33.8 \({}^{\circ}\)C/min [15]. [PERSON] et al. prepared conductive asphalt concrete by adding 8% steel wool fibers (by volume of bitumen) and its induction heating was 43.8 \({}^{\circ}\)C/min [16]. [PERSON] also prepared conductive asphalt concrete by adding 8% steel wool fibers and its induction heating was 38.1 \({}^{\circ}\)C/min [17]. [PERSON] prepared asphalt concrete by adding 6% coarse steel fibers and its induction heating was 62.0 \({}^{\circ}\)C/min [18]. In the aforementioned research, the induction heating speeds of the asphalt mixtures designed still need to be improved to allow fast onsite healing on asphalt pavement.  
In this paper, steel slag and steel fiber composite asphalt mixture was prepared to enhance the induction heating speed and healing efficiency. Asphalt mixtures containing steel fiber or steel slag were also prepared for comparison. The water stability, mechanical properties, thermal parameters, heating/cooling characteristics, and healing ratios of different asphalt mixtures were studied.