# Analysis of the Odor Purification Mechanism and Smoke Release of Warm-Mixed Rubber Asphalt
## 1 Introduction  
In recent years, the number of cars in China has increased sharply, and more and more tires have been scrapped. With the implementation of the national \"dual carbon\" strategy and the improvement of people's awareness of environmental protection and health, theefficient comprehensive utilization technology of discarded tires, one of the bulk solid wastes, is increasingly receiving attention. Processing waste tires into rubber powder for asphalt modification can effectively reduce their impact on the environment. Conventional hot-mixture asphalt (HMA) is made of mineral aggregate and asphalt cement at high temperature. In the process, it consumes large amounts of energy and produces a large number of harmful gases and greenhouse gases. Compared with the traditional HMA, the warm-mix asphalt (WMA) method used in this study can produce asphalt mixtures at lower temperatures, which can not only reduce the generation of harmful gases and protect the environment, but can also maintain the stable performance of the asphalt mixture or lead to better performance, improving the compaction, track resistance, fatigue resistance, and durability. Use of WMA can not only reduce the total usage of high-energy consumption asphalt products, but also effectively improve the road performance of asphalt mixtures [1]. However, rubber asphalt can produce toxic smoke with a foul odor during production and construction, which seriously restricts the large-scale promotion and application of rubber asphalt [2]. Therefore, researchers have begun to investigate smoke-suppression and odor-purification technology of rubber asphalt, and the basis for this work is the need to clarify the generation and diffusion mechanism of rubber asphalt smoke [3]. However, further research is needed on how volatile smoke is generated along with the complex chemical reaction of rubber powder in asphalt. During the production process of rubber asphalt, the rubber powder undergoes complex chemical reactions such as desulfurization and degradation, and at the same time produces a large amount of smoke containing irritating odors [3]. However, under the same temperature conditions, heating rubber powder or asphalt alone does not produce such a phenomenon, indicating that the formation of foul-odor smoke components is accompanied by the desulfurization and degradation of rubber powder, and the desulfurization and degradation process of rubber powder in asphalt is accompanied by the generation reaction of smoke [4]. At present, research on the release of asphalt smoke has achieved some results, but mainly focuses on the volatile components in the matrix asphalt smoke [5]. Research on rubber asphalt smoke also mostly analyzes the smoke components, and has not established a quantitative corresponding relationship between smoke generation and the rubber powder desulfurization and degradation process, resulting in insufficient understanding of the deep principles of smoke generation [6]. In addition, there is no systematic study on the conditional factors and dynamic evolution process of the volatilization of rubber asphalt smoke, and there is a lack of analysis of the entire construction process of the smoke composition and release rate changing with time and spatial scene conditions [7]. Especially during the mixing and paving stages of asphalt mixtures, the specific surface area of rubber asphalt increases after contact with aggregates, providing a more favorable environment for the release of smoke [8]. There is a lack of systematic analysis on the generation and diffusion of smoke from rubber asphalt under high temperature and large specific surface area exposure, and in-depth comparative research has not been conducted on different types of modified asphalt rubber and application scenarios under different conditions, making it difficult to provide targeted measures to suppress the odor and smoke of rubber asphalt [9].