# Analysis of the Odor Purification Mechanism and Smoke Release of Warm-Mixed Rubber Asphalt
## 1 Introduction
The mechanism and suppression of smoke emissions from rubber asphalt have not received sufficient attention, and the specific mechanism of the desulfurization and degradation process of rubber powder in asphalt on smoke generation is still unclear [10]. There is a lack of systematic analysis on the evolution of smoke emissions with construction space and time conditions. In order to effectively solve the limitations of smoke emissions on the large-scale application of rubber asphalt, it is necessary to carry out basic theoretical research in this area [11]. At present, scholars have conducted research on the composition and influencing factors of asphalt smoke, exploring the mechanism of asphalt smoke generation [12; 13]. The smoke of asphalt comes from the physical and chemical reactions during heating. The temperature sensitivity of lightweight components is high, and they are easy to decompose and volatilize at high temperatures [11]. The molecular weight of heavy components is high,and their molecular structure is complex, with low temperature sensitivity. When the heating temperature is high, the side chains break and decompose into small molecules. When asphalt molecules evaporate and decompose at high temperatures, they will react with oxygen to generate new substances and discharge them into the air [14]. There are various types of asphalt smoke, mainly including saturated hydrocarbons, aromatic hydrocarbons, oxygen-containing, nitrogen, and sulfur heteroatom compounds. Asphalt smoke contains harmful and foul-smelling gases, as well as polycyclic aromatic hydrocarbons containing more than two benzene rings, which are carcinogenic. Heating asphalt produces volatile organic compounds (VOCs), which cause changes in its internal composition and properties, especially affecting the light components (saturated and aromatic) significantly [15]. [PERSON] et al. collected asphalt smoke and found that its components contained hundreds of organic compounds, including many toxic carcinogens [16]. Research by [PERSON] et al. revealed that VOCs in asphalt include alkanes, olefins, hydrocarbon derivatives, benzene series compounds, and sulfur-containing substances. Short-chain alkanes and olefins originate from the heating decomposition of asphalt, while benzene series compounds are formed by the volatilization of benzene-containing components in asphalt and the side chain cleavage condensation reaction of asphalt molecules [17]. [PERSON] et al. studied the smoke emissions of rubber powder modified asphalt and found through gas chromatography-mass spectrometry that the smoke components include alkanes, benzene derivatives, ketones, aldehydes, acids, alcohols, thiophenes, and thiazoles. The smoke emissions of asphalt increased with the increase in rubber powder content [18; 19]. Existing research on asphalt smoke indicates that the amount of smoke generated by asphalt heating is relatively large, including volatile substances and foul-smelling substances. The release of smoke causes changes in the internal composition and viscosity of asphalt. The source and temperature are factors that affect the level of smoke release. The study of asphalt smoke is beneficial for further research on asphalt smoke and odor control methods. The source and type of asphalt are among the main factors affecting smoke [20]. [PERSON] et al. selected six different sources of asphalt for research, and the results showed that the asphalt source and heating temperature have a significant impact on the content of polycyclic aromatic hydrocarbons in asphalt flue gas [21]. [PERSON] et al. used powder and liquid deodorizers to mix into rubber asphalt to prepare purified asphalt. The study found that a 0.1% dosage of deodorizers can ensure that the basic performance of asphalt meets requirements and achieves a deodorization effect [22]. [PERSON] et al. found that dual-component deodorizers have a more significant smoke suppression effect on hot mix Styrene-Butadiene-Styrene (SBS) mixtures than single-component deodorizers [23].