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Article

Characterization of Fume Suppression Effect and Performance of SBS-Modified Asphalt with Deodorant

by
Yinan Guo
1,2,
Yu Zhao
3,
Lianghao Sun
4,
Xiuchen Xu
4,* and
Hongchao Zhang
4
1
Chengdu Jiaotou Construction Co., Chengdu 610043, China
2
Chengdu Communications Investment Group Corporation Limited, Chengdu 610041, China
3
Chengdu Jiaotou Transportation Construction Management Group Co., Chengdu 610041, China
4
The Key Laboratory of Road and Traffic Engineering, Ministry of Education, Tongji University, Shanghai 201804, China
*
Author to whom correspondence should be addressed.
Processes 2024, 12(11), 2603; https://doi.org/10.3390/pr12112603
Submission received: 11 October 2024 / Revised: 6 November 2024 / Accepted: 16 November 2024 / Published: 19 November 2024
(This article belongs to the Section Chemical Processes and Systems)
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Versions Notes

Abstract

:
SBS-modified asphalt produces a large number of hazardous fumes in the preparation process, which severely endangers health and causes environmental pollution. This paper details the design of a fume generation and collection device for asphalt and proposed a comprehensive method for analyzing fume composition. Two deodorants were incorporated into SBS-modified asphalt to mitigate the hazards of the original hazardous emissions. Then, ultraviolet–visible spectrophotometry, gas chromatography–mass spectrometry, and Fourier-transform infrared spectroscopy were combined to analyze the main component differences between asphalt fumes before and after adding deodorant, and to specify the mechanism of action of deodorants on hazardous fumes and SBS-modified asphalt. Finally, the road performance, including the physical and rheological properties of SBS-modified asphalt blended with deodorant, was evaluated. The results indicated that both deodorizers were effective in reducing the emission of hazardous substances in the fumes of SBS-modified asphalt, and no new hazardous substances were generated. Under hot mixing conditions, the addition of 0.3% of deodorant A (high boiling point ester) was effective in reducing the emission of volatile organic compounds (VOCs) by up to 41.7%, while the reduction in benzene congeners reached at least 50%. On the other hand, 1% of deodorant B (silica–magnesium compounds) reduced the emissions of VOCs and benzene congeners by 36% and 20–42%, respectively, under the same conditions. Furthermore, the addition of deodorant did not affect the original road performance, and even improved the rheological properties to a certain extent, which was conducive to the application of deodorant in pavement engineering.

1. Introduction

Asphalt pavement has become the most widely used high-grade pavement due to its superior performance and its smooth surface, low noise, and short construction period [1]. Asphalt is also used as a binder in roofing and waterproofing of underground structures [2]. However, with the rapid development of automobile ownership and the gradual increase in climate warming, asphalt will be subjected to a more severe combination of traffic load, intense light, and high temperature and oxygen, which will result in the deterioration of asphalt pavement performance [3,4,5]. Therefore, nowadays, the traditional asphalt binder does not meet the requirements for higher road performance.
Several studies have investigated new approaches to tackling road performance by asphalt modification technology using materials such as fiber [6,7], rubber [8], resin [9], plastic [10], and antiaging agents [11]. Among these modifiers, styrene–butadiene triblock copolymers (SBS) have been the most successful in the modification of asphalt for pavements, especially in terms of high and low temperature and fatigue-resistance performance [12,13].
The asphalt binder is heated to the liquid phase at high temperatures and mixed with the aggregate to form a loose asphalt mixture. Asphalt releases a large number of substances including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and a small amount of C, N, and S oxides during high-temperature production [14,15,16]. Some of these emissions, such as naphthalene, pyrin, anthracene, phenol, and pyrrole, are hazardous or even carcinogenic and harmful to human health [17]. At the same time, these emissions could also lead to environmental pollution phenomena such as acid rain and haze, which poses a serious threat to the environment and the health of other animals [2]. Asphalt composition, the type of crude oil, and the degree of oxidation of the asphalt itself are the main factors that determine the levels of VOCs and PAHs [18]. The presence of modifiers such as SBS modifiers mitigates the emissions of harmful substances to some extent [19]. A study by Lei et al. discovered that SBS modifier blended in matrix asphalt could absorb aromatic hydrocarbons to reduce the emission of asphalt VOCs [20]. Other researchers found that the VOCs released from asphalt materials could be reduced by the combined use of SBS and activated carbon filler [21], and the replacement of the petroleum matrix with styrene–butadiene–styrene (SBS) and crumb rubber (CR) as raw materials in asphalt could effectively improve the performance of hybrid bio-asphalt [22]. The mixing of waste crumb rubber with petroleum asphalt exacerbates the formation of sulfurous fumes and PAHs, which can cause severe adverse reactions in people exposed to these gases [23]. Therefore, the effective inhibition of harmful fumes from asphalt is particularly important and these compounds may also have potential applications in future asphalt mixtures.
Burstyn et al. [24] established a relationship model between the average exposure amount and time of asphalt fumes, and first proposed that reducing the temperature of asphalt treatment and application as well as alternative cleaning products could effectively reduce workers’ exposure. Later, some methods to reduce construction temperatures, such as warm mix asphalt technology [25] and cold mix asphalt technology [26], were gradually developed. These measures could mitigate, to different degrees, the pollution caused by the fumes of asphalt, but the suppression capacity had its limitations [27]. Some studies have specially developed new approaches to solving emission release from the production process using porous materials such as activated carbon [28] and Ca(OH)2-incorporated zeolite [29] as modifiers incorporated into the bitumen to inhibit the volatilization of bitumen components via interlayer adsorption and chemical bonding interactions. However, these studies do not clearly show the process of inhibiting toxic gases at the source and substances such as activated carbon are less stable. Other researchers have adopted alkanolamine warming agents [30,31] and organic montmorillonite (MMT) [32] to inhibit the emission of asphalt VOCs. Among them, the former reduces the internal surface tension of the asphalt to allow the asphalt to cover the aggregate at room temperature, and the latter reduces the internal temperature of the asphalt material to mitigate the decomposition of the molecules. However, both of these warming agents can affect the road performance of asphalt mixtures to a certain extent. Moreover, polymer modifiers such as SBS can also inhibit the release of VOCs during asphalt production by constraining the path of VOC molecules through the polymer modifier’s own mesh structure [21]. Li et al. analyzed the VOC release characteristics of matrix asphalt and SBS-modified asphalt at different temperatures, and found that SBS modifiers could effectively reduce VOC emissions during the heating process of asphalt. However, the inhibition effect decreased when the temperature reached 220 °C. This may have been due to the degradation of SBS modifier at high temperatures [20].
The fume problem of asphalt mixtures has attracted much attention, but there are fewer studies on the identification and quantification of the actual fume components, and even fewer studies on the control of fume emissions. Accordingly, this study details the design of a fume generation and collection device for asphalt and proposes a comprehensive fume composition analysis method. Two different types of deodorizers (a high-boiling-point ester and a silicon–magnesium type) were used to mitigate asphalt fume emissions. Ultraviolet–visible (UV) spectrophotometry was first conduced to identify the content of total emissions and to consider the effect of deodorants with different dosages on the VOCs in SBS-modified asphalt. The collected fumes were characterized using gas chromatography–mass spectrometry (GC-MS) to quantify the composition of emissions. Meanwhile, the mechanism of action of the deodorant was also analyzed via GC-MS and Fourier-transformation infrared spectroscopy (FT-IR) before and after the addition of deodorant. Finally, the physical and rheological properties of SBS-modified asphalt were compared before and after the deodorization. This study aimed to reveal the suppression effect of deodorant on SBS-modified asphalt fumes and its influence on the properties of the asphalt when used in asphalt pavements.

2. Materials and Methods

2.1. Raw Materials

The SBS-modified asphalt investigated in this study was prepared by blending base asphalt with SBS. Two different types of deodorizers, one a high-boiling-point ester with a viscosity-stabilizing effect, and the other a silicon–magnesium type with extremely high adsorption power were used. These are commercially available, respectively, from Hangzhou Dalick Chemical Co., Ltd. of Zhejiang and Quanzhou Kejun Chemical Co., Ltd. of Fujian, China. Chemical reagents, such as cyclohexane and other materials, were also needed to treat and collect the fumes during the tests. The fundamental properties and functions of the raw materials are shown in Table 1.

2.2. Fume Collection Process of SBS-Modified Asphalt

The fume collection system for the SBS-modified asphalt with/without deodorizer had three components: (i) an asphalt fume generator, (ii) an organic substances absorption device, and (iii) a gas collection device, as shown in Figure 1. The prepared SBS-modified asphalt with/without deodorizer was first poured into the asphalt fume generation device, which consisted of a magnetic agitator, a three-necked flask (storage and mixing container), a stirring paddle (stirring), and a digital display thermostatic heating device and a temperature probe (monitoring temperature). The generating device could regulate the amount of asphalt fumes generated under different heating temperatures, heating times, and stirrer speeds. The stirrer speed was set to 300 r/min, and the asphalt was heated to 180 °C for 1 h, and then collected through the enrichment device. The appropriate absorption solution (organic substance) and gas collection bag were selected for the enrichment device to collect the fumes with different phases and compositions by controlling the test time. When the time reached 1 h, silicone tubing was used to connect the bubble tubes to the right side of the three-necked flask, and the sampling pump was turned on to pump at a rate of 500 mL/min. Subsequently, the corresponding substances were collected through the cyclohexane solution and the gas bag.
High-purity cyclohexane solution was selected as the absorbing material for organic substances. This solvent is commonly characterized as the standard material for chromatographic analysis due to its low toxicity, good solubility, and absence of reaction with the solute. To further enhance the dissolution of the organic material by the cyclohexane solution, two sets of absorption tubes containing high-purity cyclohexane solution were used. Moreover, in order to reflect the content of gas particles more clearly, the inner wall of the absorber tube was further cleaned with cyclohexane, so that the asphalt gas particles adhering to the inner wall of the absorber tube were fully dissolved. The gas bag showed good sealing performance and did not cause contamination of the sample.

2.3. Test and Evaluation Methods

2.3.1. Ultraviolet–Visible Spectrophotometry

Ultraviolet–visible (UV) spectrophotometry provides absorption spectra in the UV spectral region, and is widely used to determine the content of organic and inorganic compounds. The cyclohexane solution was used instead of benzene solution to dissolve the asphalt fumes. The Beer–Lambert law states that the absorbance of a solution is proportional to the concentration and thickness of the solution, which indicates that the absorbance of a solution at a certain wavelength is equal to the linear superposition of the absorbance produced by each monomer in the solution. The instrument employed in this study was a U-3310 UV spectrophotometer. The spectral measurement range was set at 200 nm to 300 nm with an interval of 0.5 nm, and the wavelength absorption at 288 nm was characterized as the main evaluation parameter to analyze the effect of the deodorant [33,34]. Moreover, the cyclohexane solution, after absorbing asphalt fumes, was poured into an evaporating dish placed in a thermostatic water bath at 60 °C. The mass of the asphalt fumes was obtained using an analytical balance. Multiple sets of standard samples with different asphalt fume concentrations were then configured. More specifically, the asphalt fumes in the evaporating dish are dissolved with a certain volume of cyclohexane to configure a standard solution with a concentration of 10 μg/mL, which was then diluted with cyclohexane solvent for different times to obtain several sets of solutions. Finally, the absorbance of the diluted samples was measured.

2.3.2. Gas Chromatography–Mass Spectrometry (GC-MS)

Fume components and concentrates were characterized by a gas chromatography–mass spectrometry (GC-MS) system equipped with an electron ionization (EI) and quadrupole mass analyzer (Agilent 7890A-5975C). A chromatographic column of HP-5 ms (30.0 m × 250 μm × 0.25 μm) was used to separate the chemical substances in the asphalt fumes, and helium was introduced as carrier gas with a flow rate of 1.2 mL/min. For the GC analysis, the initial temperature was kept at 74 °C for 3 min. Then, the temperature increased to 200 °C at a rate of 6 °C/min, and finally, to 280 °C at a rate of 8 °C/min (held for 8 min). The species of chemical substances in the fumes were determined by the position of the ion chromatographic reaction peaks, and the relative concentrations of each component were compared based on the peaks of the chromatographic curves. It is worth mentioning that the cyclohexane solution of the absorbed fumes needed to be filtered through a filter hole (to remove insoluble particles larger than 0.22 µm) before it could be put into the GC-MS equipment for detection.

2.3.3. Fourier-Transform Infrared Spectroscopy (FT-IR)

The Fourier-Transform infrared (FTIR) spectrometer from Thermo Fisher’s Nicolet 6700, USA, was applied as one of the techniques for the simple identification of chemical functional groups in different asphalt samples within the wavenumber range of 400–4000 cm−1.

2.3.4. Physical Property Tests

Classical asphalt physical tests were used to verify the compatibility of deodorant with SBS-modified asphalt. Three properties were evaluated at different doses of deodorant, namely penetration at 15, 25, and 30 °C (ASTM D5), softening point (ASTM D36), and ductility at 5 °C (ASTM D113). All three properties were measured in triplicate, and the average values were recorded.

2.3.5. Rheological Property Tests

The dynamic shear rheological tests were characterized using a dynamic shear rheometer in compliance with ASTM D7175. The diameter of the two parallel plates was 25 mm and the gap was 1 mm. The temperature sweeping started at 58 °C and increased at a rate of 2 °C/min until the final temperature reached 88 °C. Rheological parameters such as the dynamic shear modulus G*, phase angle δ, and G*/sin δ were measured.

3. Results and Discussion

3.1. Characterization of Total Fumes

Before the concentration of asphalt fumes could be formally measured, a calibration curve for the concentration of asphalt fumes needed to be identified. This was defined by testing the absorbance of incident monochromatic light of different wavelengths passing through a sample solution with a fixed absorption concentration. On the one hand, a fixed volume of cyclohexane solution was used to adsorb a known amount of asphalt fumes to obtain different concentrations of the solution. On the other hand, the cyclohexane solution after the absorption of asphalt fumes was evaluated by UV spectrophotometry.
The wavelength of 288 nm was used as a characteristic wavelength for the absorption of asphalt fumes by cyclohexane. The relationship between the absorbance and fume concentration was thus determined, as shown in Figure 2. It was obvious that a linear correlation existed between the absorbance and fume concentration. The coefficient of determination, R2 = 0.9963, was used to confirm the high fitting degree and applicability. Therefore, the absorbance of the solution without deodorant was formulated to be around 0.8 via adjusting the time of asphalt fume collection.
Figure 3 displays the effect of VOC reduction from deodorants A and B in the SBS-modified asphalt. The introduction of deodorizers resulted in a significant reduction in VOCs. For deodorant A, the optimum suppression effect of VOCs was 41.7% when the concentration reached 0.3%. Thereafter, as the content continued to increase, the absorption of VOC emissions stagnated or even deteriorated. This indicated that for high-boiling-point ester deodorant, it was necessary to determine the optimum dosage in VOC emissions when adding the deodorant. This avoided the decline in efficacy caused by excessive dosage. For deodorant B, a higher concentration resulted in a lower emission for all the compounds, indicating that the deodorant concentration was a highly influential factor in SBS asphalt emissions. It is worth noting that the reduction in VOCs showed a decreasing trend as deodorant B increased. In particular, when the concentration rose from 0.7 to 1%, the degree of reduction was only 1.5%. Therefore, considering the effect on asphalt properties and the cost of preparation, the optimum dosage of deodorant B was 1%, at which time the inhibition effect of VOCs was 36%.

3.2. Composition Analysis of Fumes

The GC-MS chromatograms of the SBS-modified asphalt without deodorant tested under different temperatures are shown in Figure 4a. For the SBS-modified asphalt, high temperature caused higher emissions for all the compounds. In regard to the flue emissions, it was found that the alkanes, benzene homologs, and others increased quickly with an increase in temperature. Although the temperature increased by only 20 °C from 190 to 210 °C, the total emissions increased approximately 2.24 times, of which benzene congeners, naphthalenes, and thiophenes increased by about 3 to 10 times. Combined with previous studies [20], this indicated that flue emissions do not show a linear relationship with increasing temperature, but more likely, an exponential relationship. GC-MS detection indicated that the main components of SBSMA fumes in the first 25 min were alkanes and benzene homologs, which are the primary chemical components of petroleum asphalt. The main components of SBSMA and deodorized SBSMA after incorporating deodorants are shown in Figure 4b. It can be seen that the concentration levels of 1,2,3-Trimethylbenzene, p-Xylene, o-xylene, 2-Methylnaphthalene, and some other more toxic substances decreased when deodorants A and B were used. Combined with Figure 4, each peak of GC-MS was integrated to obtain the corresponding peak area, and the dive percentage contents are shown in Table 1, using the area normalization method. As can be seen from Table 2, there were nearly 30 organic compounds in 10 categories in the fumes, including olefins, alkanes, amines, benzenes, naphthalenes, phenols, thiophenes, methyl esters, alcohols, and mercaptans. Among these components, pungent odor developed with high heating temperature for all except the alkanes.
The contents of 1,2,3-Trimethylbenzene (RT = 5.54 min) and o-xylene (RT = 8.49 min) were higher than those of the other benzene homologs. Compared with the relatively minor toxicity of most alkanes, benzene and its homologs pose a greater risk to the environment and human safety. Apparently, the addition of deodorant A resulted in a significant reduction in toxic chemicals emitted from asphalt. The abundance of all benzene congeners was reduced by at least 50% and several of the more toxic benzene congeners could even be reduced to about 70%. Meanwhile, the addition of deodorant A reduced the content of 1-decene, 3′-Methylacetanilide, and 2,2′-Methylenebis (6-tert-butyl-4-methylphenol) by 90%, 70%, and 63%. On the other hand, deodorant A had little effect on the inhibition of long alkanes in flue emissions, and even increased the content of some long alkanes, which may have been due to the formation of C-C bonds of alkanes by ester deodorants at high temperatures. In comparison, deodorant B did not increase the content of long alkanes, and did not play an effective role in the mitigation of other harmful substances.

3.3. Functional Groups of SBSMA Before and After Deodorization

Infrared spectroscopy was used for analysis of the functional groups in each sample, determined by their specific wavenumber range in the infrared absorption peak. Figure 5 shows the change trends and curve shapes of SBS-modified asphalt with deodorant. Compared with SBS-modified asphalt, neither of the SBS-modified asphalts with the two deodorizers produced new characteristic peaks, which indicated that the addition of the deodorizers did not generate new chemical bonds or break old chemical bonds. The main difference between the SBSMA and the deodorized SBSMA might be the intensity of their absorption peaks.
The characteristic peak at wavenumbers 650 to 910 cm−1 was substantially reduced, which revealed the weakening of the out-plane bending vibration of the C-H plane on the benzene ring. This change suggested that the structure of the benzene ring may have been altered by the addition of the deodorizer, and that the concentration of benzene and its analogues could also have been reduced relatively substantially. This phenomenon was consistent with the results of GC-MS for the determination of benzene and its congeners with lower concentration in deodorized SBSMA fumes. Benzene and its derivatives are recognized as hazardous substances, which is important for improving the emission of harmful gases in the environment. The absorption peaks at 1375 cm−1 and 1458 cm−1 were the superposition of -CH2- bending vibration and -CH3- asymmetric bending vibration. The frequency of the former bending vibration was similar to that of the latter asymmetric bending vibration. This is the reason for the overlapping frequency bands shown on the curves. These characteristics showed that deodorizers affect the chemical environment of saturated and unsaturated hydrocarbons in asphalt, possibly influencing the bonding and elastic properties of asphalt by altering the microstructure. Saturated hydrocarbons play a role in asphalt by enhancing plasticity and improving bonding, while unsaturated hydrocarbons are related to the aging process of asphalt. Moreover, the absorption peaks at 2850 cm−1 and 2916 cm−1 were identified as the stretching vibrations of C-H in cycloalkanes and alkanes, which resulted in the decrease in the total alkanes. This may have been due to the fact that certain components of the deodorizer react with the alkanes in the asphalt and change its chemical composition, which may affect the asphalt’s aging resistance and temperature sensitivity.

3.4. Physical Properties and Effects of SBSMA with Deodorant

The effects of different deodorant dosages on the physical properties of SBSMA are shown in Figure 6. Addition of deodorant A increased the penetration and reduced the softening point. High penetration indicated poorer resistance to high temperature and better resistance to low temperature. Asphalt mixtures with lower temperature sensitivity exhibit stronger resistance to rutting and cracking [35]. Our results showed that the increase in the amount of deodorant A led to fluctuation in the normal properties such as softening point and ductility. The softening point of SBS-modified asphalt reached its maximum when the concentration of deodorant A was 0.1%, demonstrating the best stability. Thereafter, the softening point decreased as the concentration of deodorant increased, which would somewhat affect the stability and creep properties of the asphalt. It can also be seen from Figure 6c that the ductility declined sharply with the initial incorporation of deodorant A. This phenomenon also reflected the low-temperature performance of deodorant A below 5 °C. The addition of deodorant B resulted in little change in its physical properties compared to SBSMA. In fact, deodorant B was a white powdered deodorant with excellent adsorption and had almost no chemical interaction with the asphalt itself. This was the reason the normal properties were not susceptible to the dosage of deodorant.
Corresponding tests were carried out and it was found that the greater the amount of deodorizer, the smaller the concentration of harmful substances in asphalt fumes. However, the physical properties of deodorizer A, which had better deodorization performance, were affected by its concentration. Therefore, it is recommended that 0.3% of deodorizer A and 1% of deodorizer B be incorporated as the recommended amount of subsequent SBS-modified asphalt.

3.5. Rheological Properties and Effects of SBSMA with Deodorant

Rheological property testing is one of the most commonly used methods for evaluating asphalt road performance in the laboratory. Figure 7 shows the variation in complex shear modulus G*, phase angle δ, and rutting resistance G*/sin δ with temperature for SBS-modified asphalt at six temperatures. The trend of complex shear modulus (G*) as a direct indicator of deformation resistance of asphalt with temperature was crucial in assessing the service life and performance stability of the material. In this study, it was observed that the complex shear modulus of both the conventional SBSMA and the deodorized SBSMA had a tendency to decrease significantly with increasing temperature until it stabilized. This was due to the fact that the increase in temperature made the asphalt more viscous, resulting in its internal structure being more prone to movement under external forces. Moreover, the complex shear modulus G* of the deodorized SBSMA was significantly higher than that of the conventional SBSMA in the temperature range of 58–76 °C, which indicated that the deodorizer may have increased the cohesion of the material by enhancing the intermolecular interactions within the asphalt, thus improving its structural stability at higher temperatures. In other words, the deodorizer caused a significant improvement by enhancing the deformation-resistance properties of the original asphalt. It is worth mentioning that deodorant B exhibited superior performance to that of deodorant A after the temperature exceeded 76 °C. This may have been due to the fact that deodorant B was a powder structure with a rough surface and a large adhesion area with asphalt, which formed strong intermolecular forces.
The phase angle (δ), as a measure of the viscoelastic properties within an asphalt mixture, reflected the relative ratio of elastic to viscous response of the material when stressed. It could be observed that the phase angle of all the samples increased with increasing temperature at the beginning of the warming period, which was due to the fact that high temperature enhances the viscous properties of asphalt materials. However, the deodorized SBSMA, especially with deodorant B, showed a slower rate of increase in phase angle at high temperatures. This may have been due to the powdery structure and large adhesion area of deodorant B, which formed stronger intermolecular forces and physical bridges within the asphalt matrix, enhancing the elastic component of the asphalt. Therefore, it was able to maintain a lower phase angle at high temperatures and exhibited a stronger resistance to high temperature deformation than deodorant A.
The Strategic Highway Research Program (SHRP) specification defined G*/sin δ as the rutting factor, which is used to evaluate the resistance of asphalt to rutting deformation at high temperature, corresponding to a temperature value of G*/sin δ = 1 KPa at the upper limit of the service temperature. The curve of G*/sin δ vs. temperature was almost similar to the curve of G* vs. temperature, except for the difference in magnitude. It was verified that both deodorizers could effectively improve the high temperature deformation resistance of asphalt based on the rutting resistance G*/sin δ.

4. Conclusions

This research mainly aimed to determine the detailed composition of the fumes of SBS-modified asphalt and to analyze the effects on odor and the release of toxic gases of the incorporation of two types of deodorizers and explain the mechanism of action of these deodorants. Based on the test results, some conclusions can be drawn:
(1)
The fumes produced in the preparation and production of SBS-modified asphalt are a mixture of solids, liquids, and gases. The designed fume generation and collection system could effectively collect the various fume components of asphalt, which could then be analyzed and evaluated accurately by different chemical tests.
(2)
UV spectrophotometry indicated that both deodorizers showed good inhibition of total VOC emissions from SBS-modified asphalt. When the high-boiling-point ester, deodorant A, was selected (the optimal dosage was 0.3%), it was able to reduce the emission of VOCs by 41.7%. Adsorbent deodorant B (optimal dosage of 1.0%) had a relatively weak inhibitory effect and was able to reduce VOC emissions by 36%.
(3)
The GC-MS test revealed that the main components of SBS-modified asphalt were alkanes and benzene congeners, and the hazardous substances were benzene congeners, naphthalene, thiophene, methyl ester, and mercaptan. Deodorizers A and B significantly reduced the production of benzene congeners, especially the former, which reduced them by at least 50%. Both deodorizers achieved both deodorization and environmental protection and did not produce new harmful substances.
(4)
FTIR and GC-MS tests clarified the effect and mechanism of deodorant on SBS-modified asphalt. After incorporating deodorant, several absorption peaks in asphalt decreased to different degrees, and no new characteristic peaks appeared.
(5)
The addition of both types of deodorizers had little effect on the conventional physical properties of SBS-modified asphalt, which proved that they would not affect the actual road performance. Even the rheological properties of raw SBS asphalt could be effectively enhanced when an optimal amount of deodorant was incorporated.

Author Contributions

Conceptualization, Y.G.; Software, Y.G. and X.X.; Validation, Y.G.; Formal analysis, Y.Z. and X.X.; Investigation, Y.Z.; Resources, Y.Z.; Data curation, L.S. and X.X.; Writing—original draft, Y.G.; Writing—review & editing, H.Z. and X.X.; Visualization, X.X.; Supervision, H.Z.; Project administration, Y.Z.; Funding acquisition, Y.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Sichuan Province Transportation Science and Technology Project. The name of the project is Research on Application of New Materials for Cangba Expressway (No. 2022-ZL-05).

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data are not publicly available due to commercial privacy.

Acknowledgments

The authors are especially grateful to Sichuan Chengmian Cangba Expressway Company Limited for project funding.

Conflicts of Interest

Author Yinan Guo was employed by the company Chengdu Jiaotou Construction Co. and Chengdu Communications Investment Group Corporation Limited.; Author Yu Zhao was employed by the company Chengdu Jiaotou Transportation Construction Management Group Co. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Processes 12 02603 g001
Figure 1. Schematic diagram of the asphalt fume generation and enrichment system.
Figure 1. Schematic diagram of the asphalt fume generation and enrichment system.
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Figure 2. Calibration curve of asphalt fume concentration and absorbance.
Figure 2. Calibration curve of asphalt fume concentration and absorbance.
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Figure 3. Effectiveness of deodorizers in suppressing the VOC content of SBSMA.
Figure 3. Effectiveness of deodorizers in suppressing the VOC content of SBSMA.
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Processes 12 02603 g004aProcesses 12 02603 g004b
Figure 4. GC-MS of SBSMA and deodorized SBSMA.
Figure 4. GC-MS of SBSMA and deodorized SBSMA.
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Figure 5. FTIR spectra of SBSMA and deodorized SBSMA.
Figure 5. FTIR spectra of SBSMA and deodorized SBSMA.
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Figure 6. Physical properties of SBSMA at different deodorant dosages.
Figure 6. Physical properties of SBSMA at different deodorant dosages.
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Figure 7. Rheological parameters of SBS-modified asphalt samples.
Figure 7. Rheological parameters of SBS-modified asphalt samples.
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Table 1. Fundamental properties and functions of raw materials.
Table 1. Fundamental properties and functions of raw materials.
MaterialsBasic PropertiesFunctions
SBS-modified asphaltPenetration (25 °C, 0.1 mm)62.5Providing asphalt material before adding deodorant
Softening point (°C)80.3
Ductility (5 cm/min, 5 °C, cm)44.9
Deodorant AHigh-boiling-point ester Reducing harmful flue emissions in SBS-modified asphalt
Transparent liquid
Deodorant BBulk density (g/mL)0.28
Silicon–magnesium type: magnesium oxide, silicon dioxide, white powder--
CyclohexaneChemical formulaC6H12Absorbing organic substances in asphalt fumes
Relative density (g/mL)0.778
Purity (analytical purity, %)99.5
Water ≤ 50 ppm--
Teflon gas sampling bagFluorinated ethylene--Collecting gas
Propylene--
Table 2. The compositions and content of fumes for SBSMA.
Table 2. The compositions and content of fumes for SBSMA.
RT (min)CompoundsContent (wt%)
SBSMA (190 °C)SBSMA (210 °C)SBSMA+A (210 °C)SBSMA+B (210 °C)
3.17Nonane6.426.247.285.81
4.771-decene0.080.790.10.32
4.93Decane6.9114.485.0110.26
5.541,2,3-Trimethylbenzene1.0320.771.88
6.78p-Xylene0.180.410.280.48
7.17Undecane5.856.43.285.45
7.651,2,3,5-tetramethylbenzene0.080.170.060.16
7.75m-cymene0.330.50.230.45
8.49o-xylene1.774.551.824.51
9.54Dodecane4.356.913.654.27
11.691-Dodecanol0.050.250.320.35
11.85Tridecane9.788.7912.719.69
14.06Tetradecane10.576.4811.418.61
14.762-Methylnaphthalene0.291.870.561.24
16.001-Undecanethiol0.060.290.250.35
16.14pentadecane9.435.778.627.58
18.12Hexadecane6.563.75.855.34
19.05Pristane0.250.550.750.78
20.00Heptadecane3.062.165.23.03
20.324-tert-Octylphenol0.870.690.710.97
20.963′-Methylacetanilide1.111.780.761.7
21.78n-Octadecane0.710.731.451.02
23.47Nonadecane0.610.590.930.83
23.97Methyl palmitate00.4600.15
24.654,6-Dimethyldibenzothiophene0.190.750.190.5
25.04Icosane2.450.921.131
26.73Methyl stearate0.911.891.061.88
29.46Tetracosane3.130.823.241.14
29.762,2′-Methylenebis(6-tert-butyl-4-methylphenol)24.452.33.66
30.33Heneicosane2.180.942.471.31
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Guo, Y.; Zhao, Y.; Sun, L.; Xu, X.; Zhang, H. Characterization of Fume Suppression Effect and Performance of SBS-Modified Asphalt with Deodorant. Processes 2024, 12, 2603. https://doi.org/10.3390/pr12112603

AMA Style

Guo Y, Zhao Y, Sun L, Xu X, Zhang H. Characterization of Fume Suppression Effect and Performance of SBS-Modified Asphalt with Deodorant. Processes. 2024; 12(11):2603. https://doi.org/10.3390/pr12112603

Chicago/Turabian Style

Guo, Yinan, Yu Zhao, Lianghao Sun, Xiuchen Xu, and Hongchao Zhang. 2024. "Characterization of Fume Suppression Effect and Performance of SBS-Modified Asphalt with Deodorant" Processes 12, no. 11: 2603. https://doi.org/10.3390/pr12112603

APA Style

Guo, Y., Zhao, Y., Sun, L., Xu, X., & Zhang, H. (2024). Characterization of Fume Suppression Effect and Performance of SBS-Modified Asphalt with Deodorant. Processes, 12(11), 2603. https://doi.org/10.3390/pr12112603

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