## 1 Introduction  
Globally, ever-increasing traffic and growing axle loads have urged engineers and practitioners to use and adopt unconventional asphalt materials for the improvement of pavement performance [1; 2; 3; 4]. Crumb rubber (CR), which is used as a modifier for asphalt, has been proven to endow asphalt with improved properties, i.e., better rutting resistance, fatigue resistance, water stability, antireflective cracking ability, and decreased road costs [5; 6; 7]. Meanwhile, CR also provides an effective approach to solving the \"black pollution\" caused by the accumulation of waste tires [8]. Therefore, crumb rubber-modified asphalt (CRMA) and crumb rubber asphalt mixtures (CRAMs) are very popular in engineering and research. In recent years, many efforts have been made in terms of the manufacturing processes, various properties, and influences of rubber properties and asphalt. [PERSON] et al. [9] showed that the science and technology of the recycling of waste tire rubber is developing rapidly all over the world. It was found that the viscosity of CRMA will increase no matter what kind of rubber addition method is used. Recycled tire rubber also had a significant effect on the rheology of the asphalt binder, showing higher rutting resistance. [PERSON] et al. [10] found that the use of CR as a modifier of asphalt (CRMB) can improve the pavement characteristics that are added by the wet process. Furthermore, gap-graded CRAMs can be used to fight noise pollution. [PERSON] et al. [11] used a new method to investigate and model the acoustic aging of several rubberized road surfaces produced in accordance with the wet process, which were laid on three different sites. On the other hand, CR contributes to layer endurance during its service life. Therefore, reclaimed asphalt pavement (RAP) binder is often used with CRMA to make up for the adverse effects of RAP binder on the fatigue performance of mixtures [12, 13]. Some studies have further shown that this combination can provide more advantages in reducing material costs and solving waste disposal issues [14, 15, 16]. However, CRAMs exhibit problems of aging, crumb rubber swelling, storage stability, and compaction [17, 18]. Therefore, CR is modified and activated by preswelling agents, desulfurization, and plasticization to improve the compatibility of granular green rubber with asphalt [19, 20]. [PERSON] et al. [21] found that CRMA activated by microwaves exhibited minor temperature-sensitive behavior and storage stability, improved viscoelasticity, and high ductility at 5 \({}^{\circ}\)C. In addition, reactive additives such as polyphosphoric acid [22], crosslinking agents [23], and trans-polyocenamer rubber (TOR)-reactive modifier [24] have provided a new approach to improving the performance of CRMA. Among the abovementioned additives, TOR is a polymeric reactive rubber with a high amount of unsaturated bonds in its molecules, showing high reactivity [23]. It is obtained through the polymerization of cycloocene monomer through a metathesis reaction, in which cycloocene monomer is synthesized from 1,3-butadiene and 1,5-cyclocotadiene [25]. [PERSON] et al. [24, 26] found that TOR-activated CRMA improved low-temperature creep behavior, showed more obvious hardening effects after aging, and improved CRMA storage stability. Double bonds in TOR participate in chemical reactions and are beneficial for stability. [PERSON] et al. [27] showed a complex chemical reaction between TOR and CRMA at a microscopic level, which changed the rheological properties of CRAM and contributed to its storage stability. It has been noted that TOR can promote a chemical reaction between CR and virgin asphalt, which provides CR and CRMA with the characteristics of preventing cracks, waterproofing, noise reduction, simple construction technology, flexibility, good construction workability, and favorable heat storage stability [6, 28, 29]. The problem of expansion after the action of asphalt and CR is also one of the problems affecting the performance of CRAMs.