# Analysis of the Odor Purification Mechanism and Smoke Release of Warm-Mixed Rubber Asphalt
## 3 Results and Discussion
### Analysis of Asphalt Smoke Composition  
#### 3.5.1 Ammonia Gas  
As shown in Figure 5a, different types of asphalt will emit harmful gases during heating, which are caused by volatile organic compounds (VOCs) in the asphalt. The content and composition of VOCs in different types of asphalt are different, so harmful gases are emitted at different levels during heating. For matrix asphalt NA, rubber asphalt AR, and warm-mix rubber asphalt WMAR, there are differences in the degradation effect of ammonia. The ammonia concentration generated by the three types of asphalt during the experimental process is 0.383 mg/m\({}^{3}\), 0.491 mg/m\({}^{3}\), and 0.432 mg/m\({}^{3}\), respectively. Among them, the degradation effect of matrix asphalt on ammonia is the most significant, indicating that during the process of asphalt modification, rubber asphalt AR and warm-mix pure-odor asphalt WMAR contain higher volatile organic compounds, so more harmful gases are emitted during heating, and the degradation degree of modified asphalt on ammonia is reduced. When adding new materials or warm-mix agents, modified asphalt may undergo chemical reactions with asphalt, which may lead to an increase in the content of VOCs in the asphalt. The experiment was conducted by adding rubber asphalt AR and warm-mix clean odor asphalt WMAR to LD liquid and PD powder purifiers with proposed concentrations of 0%, 0.2%, 0.4%, and 0.6%. The experimental results showed that the modified asphalt with added purifiers reduced the ammonia concentration produced to varying degrees during the experiment and had better degradation effects.  
According to Figure 5b, it can be seen that for liquid deodorant (LD), when the proposed deodorant dosage is 0%, 0.2%, 0.4%, and 0.6%, the ammonia concentration generated by the purified rubber asphalt DAR in the experiment is 0.491 mg/m\({}^{3}\), 0.355 mg/m\({}^{3}\), 0.292 mg/m\({}^{3}\), and 0.271 mg/m\({}^{3}\), respectively. The degradation rate is 30.1%. The ammonia concentrations generated by DWMAR, a clean and warm-mixed rubber asphalt, in the experiment are 0.432 mg/m\({}^{3}\), 0.362 mg/m\({}^{3}\), 0.293 mg/m\({}^{3}\), and 0.271 mg/m\({}^{3}\), respectively. The degradation rate is 37.2%. For powder deodorizer (PD), when the proposed deodorizer dosage is 0%, 0.2%, 0.4%, and 0.6%, the ammonia concentration generated by the purified rubber asphalt DAR in the experiment is 0.491 mg/m\({}^{3}\), 0.345 mg/m\({}^{3}\), 0.262 mg/m\({}^{3}\), and 0.21 mg/m\({}^{3}\), respectively. The degradation rate is 57.2%. The ammonia concentrations generated by DWMAR, a clean and warm-mixed rubber asphalt, in the experiment are 0.432 mg/m\({}^{3}\), 0.317 mg/m\({}^{3}\), 0.251 mg/m\({}^{3}\), and 0.184 mg/m\({}^{3}\), respectively. The degradation rate is 57.4%, indicating that for the same type of deodorizer, an increase in the dosage of the deodorizer results in a decrease in ammonia concentration. Among them, when adding the same type and concentration of odor-clarifying agent, the degradation rate of ammonia by DWMAR, a clean and warm-mixed rubber asphalt, is higher, indicating that the coupling effect of temperature mixing agents and odor-purifying agents may increase the degradation rate of ammonia. In addition, adding the same concentration of deodorizing agent to the same type of asphalt and PD powder deodorizing agent has a better degradation effect.