# Analysis of the Odor Purification Mechanism and Smoke Release of Warm-Mixed Rubber Asphalt
## 4 Conclusions  
This study conducted experimental analysis on the basic properties, high-temperature rheological properties, workability, functional groups, and smoke composition of asphalt during the modification process of warm-mixing and deodorization. The coupling effect between deodorizers and warm-mixing agents was demonstrated. Based on various experimental data, the following main conclusions can be drawn:  
1. Infrared spectroscopy revealed that the addition of deodorants primarily induced subtle changes in carboxylic acid functional groups and possible amine functional  
Figure 11: Mixing time impact. Figure 12: Mixing speed influence. groups in asphalt, and these changes exhibited no significant differences between the two deodorant-treated asphalt samples. 2. The incorporation of deodorants can effectively reduce the ammonia concentration produced during the heating of modified asphalt. Specifically, in deodorized rubber asphalt (DAR) and deodorized warm-mix rubber asphalt (DWMAR), the ammonia concentration decreased significantly with increasing dosages of liquid deodorant and powder deodorant. Powder deodorant exhibited a better degradation effect, with a maximum degradation rate of 57.4%. Furthermore, the combined use of warm-mix agents and deodorants enhances the degradation rate of ammonia. 3. With the increase in the dosage of liquid deodorant and powder deodorant, the concentration of nitrogen oxides produced during the heating of DAR and DWMAR decreased significantly. Among them, the use of powder deodorant yielded better results, with a maximum degradation rate of 67.9%. Additionally, the combined use of warm-mix agents and deodorants further improved the degradation rate of nitrogen oxides. 4. The addition of liquid deodorant and powder deodorant to asphalt can significantly reduce the sulfur dioxide concentration produced during heating. As the dosage of deodorant increases, the sulfur dioxide concentration gradually decreases. Powder deodorant exhibits a better degradation effect, with a maximum degradation rate of 79.9% in DAR. However, it is worth noting that under the same conditions, the degradation rate of sulfur dioxide in DWMAR is slightly lower than that in DAR, which may suggest that the coupling of warm-mix agents and deodorants may generate additional sulfur dioxide or reduce its degradation efficiency. 5. With the increase in the dosage of liquid deodorant and powder deodorant, the concentration of hydrogen sulfide produced during the heating of rubber asphalt (AR) and warm-mix rubber asphalt (WMAR) decreased. Among them, the use of powder deodorant in DWMAR yielded the best degradation effect, with a maximum degradation rate of 55.9%. In addition, experimental results indicate that the combined use of warm-mix agents and deodorants can improve the degradation rate of hydrogen sulfide. 6. The mean and standard deviation of nitrogen oxide emissions are the largest, indicating the highest and most fluctuating emissions, which suggests that the coupling effect of deodorants and warm-mix agents has a significant impact on nitrogen oxides. There are differences in the degradation of harmful gases between powder and liquid deodorants. The powder type mainly purifies the air through adsorption and decomposition, while the liquid type eliminates odor molecules mainly through chemical reactions. 7. Within a certain time range, for the same type of asphalt, an increase in mixing time and mixing speed will lead to an increase in sulfur dioxide concentration during the asphalt experiment, resulting in a decrease in degradation efficiency. When the mixing time is 0.5 h and the mixing speed is 250 rpm, the sulfur dioxide emissions are the lowest. However, when the mixing time reaches 1 h or the mixing speed reaches 500 rpm, the trend in sulfur dioxide concentration changes decreases and tends to stabilize. Conceptualization, Z.C. ; Methodology, T.W. ; Validation, T.W., W.B. and S.X. ; Formal analysis, S.X. ; Investigation, T.W. and R.M. ; Resources, W.B. ; Data curation, R.M., Z.D. and Y.Z.