## 1 Introduction  
With the rapidly increase of automobiles and trucks, more than 1.5 billion waste tires are discarded every year [1]. This will inevitably lead to environmental pollution and resource wastage if we do not appropriately deal with waste tires. At present, four main methods are used to deal with these tires, namely pyrolysis [2, 3], incineration [4], landfill [5, 6], and powder manufacturing [7, 8, 9]. However, three of these four methods are accompanied by other disadvantages [10]. Pyrosis is a pioneering method that can be used to generate carbon black, tire oil, and syngas from waste tires in the absence of oxygen.  
Pyrolysis has a series of advantages, such as low cost, high efficiency, little environmental pollution, and its key product being renewable carbon black (with a mass ratio of 30% and up depending on the pyrolysis temperature) [3]. However, because of the limited usage of discarded tires pyrolysis carbon black (TPCB) nanoparticles [11], TPCB is produced and immediately accumulated. Therefore, it is very important to broaden the application range of TPCB.  
In recent years, plenty of studies have been conducted to use carbon black (CB) as a modifier for asphalt binders [12; 13; 14; 15; 16; 17; 18; 19; 20]; these works are a good start towards enlarging the application field of CB. Previous research investigated the modified effect of CB on the workability or mechanical properties of asphalt binders and their mixtures, with the results indicating that CB had good compatibility with asphalt binders and a reinforcement effect on asphalt binders, and decreased the resistivity of asphalt [12]; it could improve the complex modulus [13] and anti-aging performance (ultraviolet aging and thermo-oxidative aging) of asphalt binders [15], as well as enhance the anti-rutting performance of asphalt mixtures at high temperatures [14]. However, there was no consistent conclusion about the effect on low-temperature performance: some studies showed that carbon black could improve the low-temperature performance of asphalt, while others showed that it cannot or that it has no effect [16; 17]. However, in general, micrometer and nanometer powder materials always have a stiffening effect on asphalt and can reduce the anti-crack property of asphalt at low temperatures [18; 19; 20].  
In addition, previous research mostly studied the modified effect of industrial carbon black. The performance of CB depends on its structure, surface area, and particle size. TPCB differs from industrial carbon black in terms of its composition and structure form. For example, the particle size of TPCB is roughly equal to the average particle size of industrial carbon black, which indicates that TPCB is a compound material consisting of different kinds of industrial carbon black [10]. The desorption ability of TPCB is poor [19] and may not have good compatibility with rubber or may be difficult to disperse uniformly in asphalt. The modified effects of TPCB on the performance of asphalt binders or its mixtures may be different to industrial carbon blacks, so it is of great importance to investigate the TPCB effect on the pavement performance of asphalt binders and their mixtures.  
In this paper, the characteristic functional groups, particle size distribution, and thermostability of TPCB are studied. A base asphalt binder of Maoming GaoFu 60/80 asphalt binder (GF-70) was designated to prepare the TPCB-modified GF-70 (TPCB/GF-70) by mixing it with a 15% dosage of TPCB; the physical performance and rheological properties were investigated to evaluate the influence of TPCB on GF-70. In order to improve the low-temperature performance of TPCB/GF-70, four levels of dosage (0.3%, 0.6%, 0.9%, and 1.2%) of aromatic hydrocarbon oil (AHO) were used as the softening agent for TPCB/GF-70. Finally, two kinds of asphalt mixtures of AC-13 and AC-20 were created to investigate the influence of TPCB on the pavement performance of asphalt mixtures.