Effects of salt-induced degradation on the moisture stability and high-temperature performance of PPA/BF/SBS composite modified asphalt mixture

Asphalt pavements in coastal hot and humid regions are perennially affected by salt-induced degradation, which exacerbates moisture damage and aging processes in asphalt mixtures. To enhance the resistance to salt-induced degradation, this study employed polyphosphoric acid (PPA) and chemically modified bagasse fiber (BF) for composite modification of SBS asphalt. A systematic evaluation was conducted on the fundamental characteristics of the PPA/BF/SBS composite modified asphalt and pavement performance of its mixtures. By simulating the actual service environment of coastal pavements, a vibrating salt solution immersion test was designed to investigate the evolution of pavement performance for the PPA/BF/SBS composite modified asphalt mixture under salt-induced degradation environment. Molecular dynamics simulations were further integrated to investigate the asphalt adhesion mechanism. The results indicate that after salt-induced degradation, the penetration of all asphalt samples reduced, while the softening temperature and flow resistance increased. The composite modified asphalt exhibited the smallest changes in properties, demonstrating superior resistance to salt-induced degradation. Based on the performance variations both prior to and following salt-induced degradation, the optimal content was determined as 1.0% PPA + 3% BF. The composite modified asphalt mixture maintained higher residual stability both prior to and following salt-induced degradation, indicating effectively improved moisture and high-temperature stability. Molecular dynamics simulations further revealed that the decline in adhesion energy between PPA/BF/SBS composite modified asphalt and the aggregate in salt solution was less pronounced than that of the SBS asphalt, verifying its enhanced anti-erosion mechanism. Overall, the comprehensive pavement performance of the PPA/BF/SBS composite modified asphalt surpasses that of the SBS asphalt.

1 Introduction

In the field of road engineering, asphalt pavement is widely used. Salt-induced degradation severely impacts its serviceability and durability in salt-rich regions such as coastal areas and saline-alkali land (Wang et al., 2025). Due to the inherent pores in asphalt mixtures, environmental water can easily infiltrate the pavement structure through pressure-driven flow or capillary action (Luo et al., 2017). Under the combined effect of traffic loading, the pore water pressure exhibits cyclic positive and negative pressure loads (Li S. et al., 2025). The dynamic pore water pressure induced by tire pressure causes the salt solution on coastal pavements to form dynamic water flow, further exacerbating the deterioration of asphalt pavement (Wang. et al., 2020; Wang et al., 2022). Therefore, the impact of salt-induced degradation under vibrational loading must be considered in the design of asphalt pavements in coastal regions.

The core performance of asphalt mixture, a composite material, is governed by the properties of the asphalt binder. With increasing engineering demands, performance standards for asphalt continue to rise. A common method to enhance asphalt properties is the incorporation of modifiers into base asphalt. Among these, SBS asphalt is the most widely used in asphalt pavement applications (Gao et al., 2025). However, the incorporation of a single modifier often fails to simultaneously address multiple performance dimensions such as high-temperature stability, low-temperature crack resistance, temperature susceptibility, and storage stability. Consequently, composite modification technologies have gradually emerged as a key research focus in the field (Yalikun et al., 2025). As a widely used chemical modifier, PPA facilitates SBS to form a three-dimensional network in the asphalt matrix. This process significantly amplifies the positive impact of SBS on the overall pavement performance (Wu et al., 2020; Meng et al., 2025). Meanwhile, research (Li Z. et al., 2025) has documented that under the hot and humid coastal conditions, BF and asphalt can create a synergistic effect, leading to enhanced aging resistance for both components.

Research (Yang, et al., 2022) indicates that PPA is highly compatible with asphalt and modifies it effectively, while enhancing the material’s viscoelastic properties. Zhou et al. (2024) demonstrated through experimental investigations and molecular dynamics simulations that the incorporation of PPA modifier significantly enhances the surface free energy of asphalt. This improvement strengthens the asphalt-aggregate interface, enhances their interfacial interaction, and ultimately improves the moisture resistance of asphalt mixtures. Ziari et al. (2021) investigated the effect of PPA on the crack resistance of base asphalt. The research results showed that introducing up to 1% of PPA could enhance the crack resistance of the asphalt; however, excessive PPA would weaken the crack resistance of the asphalt. Ma et al. (2021) conducted experiments and found that the dynamic stability of the PPA/SBS composite modified asphalt mixture was 1.61 times higher than that of the SBS asphalt mixture. The fatigue life under different load strains exceeded 10,000 cycles. Wang et al. (2024) discovered that when PPA and SBS were blended to fabricate PPA/SBS modified asphalt, new characteristic functional groups emerged, indicating a chemical modification. This modification can effectively enhance performance at elevated temperatures and moisture damage resistance of the SBS asphalt. In conclusion, most of the current research focuses on the performance of PPA modified asphalt and the performance at elevated temperatures and moisture damage resistance of its mixtures, but there is relatively little research on the salt corrosion resistance of asphalt by PPA.

Fiber-modified asphalt enhances the tensile strength and ductility of asphalt mixtures. The addition of fiber materials can also mitigate pavement distress, including fatigue microcracking, ruts, and thermal cracks in asphalt mixtures, thereby reducing the crack crystallization effect caused by sea fog salt-induced degradation (Aliha et al., 2017; Shu et al., 2020). Some studies (Meneses et al., 2021; Sharma et al., 2024) have found that after the addition of BF, the loss of asphalt binder in asphalt mixtures decreases; therefore, BF can be used as a stabilizer. Mansor et al. (2018) found that the rut depth of stone mastic asphalt (SMA) mixtures without fibers was higher than that of SMA mixtures containing BF, and the dynamic modulus value of BF-containing SMA mixtures at 25 °C was higher under the full load frequency range. Ahmed (Ahmed et al., 2022) found through experimental studies that 0.3% bamboo fiber and BF can better improve the Marshall stability of asphalt, the indirect tensile strength of asphalt mixtures, and the rutting resistance. In the review by Li et al. (2023), it is mentioned that when the blending amount of BF is 3%, deformation performance of asphalt at high temperatures is significantly improved. Yang et al. (2024) found that the modified BF/SBS formulation enhanced all these properties—shear resistance, viscoelasticity, and rutting resistance—by over 20% compared to the conventional BF/SBS asphalt. Overall, BF can provide asphalt mixtures with a certain degree of tensile strength and crack resistance, reduce cracks and asphalt loss, and improve the water stability of asphalt mixtures to a certain extent. Based on the advantages of BF, this paper further investigates the effect of BF on the salt solution erosion resistance of asphalt mixtures.

Numerous methods exist for solving molecular motion systems. Based on relevant studies, the Verlet algorithm (Ruibo et al., 2020) is the most suitable for this purpose, while the COMPASS force field (Sun et al., 2016) is better adapted to asphalt materials. Thus, this paper employs the Verlet algorithm to solve molecular motion equations and the COMPASS force field to simulate the molecular motion system of SBS. In addition, recent studies have successfully employed MD simulations to elucidate the compatibility mechanisms between modifiers and asphalt. For instance, Jiao et al. (2024) utilized MD simulations to investigate the effects of styrene-butadiene rubber (SBR) and PPA on the adhesion properties of asphalt, revealing the synergistic enhancement mechanism at the interface. Similarly, Liang B. et al. (2024) analyzed the phase structure of styrene-butadiene-styrene (SBS)-modified asphalt, providing insights into the microstructural evolution during the aging process. These successful applications demonstrate that MD simulations are effective in uncovering the microscopic basis of asphalt modification, laying a foundation for the current research on asphalt composite systems.

At present, most studies on the water stability of asphalt mixtures have been conducted under a single water environment, while there are relatively few studies on asphalt under salt-induced degradation environments. In this paper, through the immersed Marshall test, high-temperature wheel tracking test, and internal salt accumulation test of asphalt mixtures, combined with the molecular dynamic simulation method, the changes in water stability and high-temperature stability between the PPA/BF/SBS composite modified asphalt mixture and the SBS asphalt mixture under salt-induced degradation environment, as well as the internal salt accumulation of the mixtures, are investigated. This aims to evaluate the salt-induced degradation resistance effect of the composite modified asphalt mixture and provide corresponding references for asphalt pavements in coastal hot and humid areas to resist salt-induced degradation.

2 Materials and methods

2.1 Materials

2.1.1 SBS asphalt

This study takes SBS asphalt as the research object. The SBS asphalt was purchased from Maoming Weilong Petrochemical Co., Ltd., Maoming City, with its specific technical specifications detailed in Table 1. The testing of these technical indicators was conducted in accordance with the JTG 3410-2025 standard (Transport, 2011).

Table 1

Table 1. Technical indicators of SBS asphalt.

2.1.2 PPA

PPA was utilized as a chemical modifier in this study, with its primary composition being a mixture of low-polymerization phosphoric acids and minor soluble inorganic compounds. Two industrial grades (105% and 115%) were initially considered, and impurity analysis confirmed that both exhibited acceptably low levels of chloride, iron, arsenic, and total metal content. However, based on previous research (Xiang et al., 2017) indicating the superior performance of the 115% PPA grade in SBS asphalt, it was ultimately selected for this investigation. The 115% grade polyphosphoric acid (PPA) used in this study was sourced from Chongqing Chuandong Chemical (Group) Co., Ltd.

2.1.3 BF

The sugarcane bagasse utilized in this study was derived from the production waste of a sugar processing plant in Guangxi. As a major sugarcane-producing region in China, Guangxi has a well-developed sugar industry. The sugarcane bagasse waste generated after sugar extraction was shredded, and fiber segments with a size range of 0.5 cm–1 cm were selected for subsequent experiments. The main components of BF include cellulose accounting for 40∼52%, hemicellulose in two ranges of 22∼26% and 17∼23%, pectin at 0.65∼0.86%, ash at 1.1∼4.2%, and it features a low cost (Anandaraj et al., 2023). The BF had an average length ranging from 0.5 to 1 cm, with an average diameter of 0.025 mm. Its average density was measured at 1.03 g/cm³.

Studies have shown hat the dosage of untreated BF is typically 3% (Li et al., 2022; Li et al., 2023). Given that this study adopts chemical treatment to remove components such as hemicellulose and lignin, the selection of a 3% dosage for preparing composite modified asphalt is sufficient to meet the research requirements.

2.1.4 Chemically modified bagasse fiber

These fibers were then stirred in a 70 °C water bath for 2 h, followed by filtration and washing with deionized water to remove residual sugars and impurities, ultimately yielding the raw BF for composite modified asphalt.

This study used chemical treatment to improve the compatibility of BF with asphalt. The specific method involved soaking in a 5% NaOH solution for 2 h and washing, then treating with a 2% CH₃COOH solution for 1 h. Finally, washing and drying at 80 °C for 24 h effectively eliminated the fiber’s hydrophilicity and improved its fracture characteristics. Figures 1, 2 show the chemically modified fiber and the modification process.

Figure 1

Figure 1. Chemical modification process of bagasse fiber. (a) NaOH treatment. (b) CH₃COOH treatment.

Figure 2

Figure 2. Flow chart of chemical treatment of bagasse fiber.

2.1.5 Preparation of PPA/BF/SBS composite modified asphalt

Previous research has demonstrated that the comprehensive performance of PPA-modified asphalt is optimal when the PPA content is within the range of 0.8%–1.5%. A PPA dosage exceeding 1.5%, however, has been shown to impart a detrimental effect on the low-temperature performance of the composite modified asphalt (Gang, 2018).

Consequently, the 115% industrial-grade PPA was selected for this study. To investigate its effect, different dosages of 0.5%, 1.0%, and 1.5% were incorporated into the composite modified asphalt. Accordingly, the modification process, illustrated in Figure 3, was designed by integrating established preparation methods for PPA-modified asphalt with those for BF-modified asphalt (Liu et al., 2016; Wang et al., 2017).

Figure 3

Figure 3. PPA/BF/SBS composite modified preparation asphalt process diagram.

2.2 Asphalt mixture composition design

In this study, basalt was used as the aggregate and limestone mineral powder as the filler, with all technical indicators complying with the requirements of the JTG 3432-2024 (Transport, 2024). AC-13 asphalt mixture was selected as the research object for subsequent salt erosion performance tests, and the gradation curve of AC-13 is shown in Figure 4.

Figure 4

Figure 4. AC-13 asphalt mixture gradation curve.

In terms of asphalt binder, based on the test results of the fundamental properties of PPA/BF/SBS composite modified asphalt in a salt erosion environment, the optimal additive proportions for SBS asphalt were determined as 1.0% PPA and 3% BF. Subsequently, Marshall tests were conducted according to current Chinese specifications (Transport, 2004) to determine the optimum asphalt content of the asphalt mixture. The test results indicated that the optimal asphalt-aggregate ratio for the SBS asphalt mixture was 4.9%, while that for the PPA/BF/SBS composite modified asphalt mixture was 5.2%.

2.3 Design of vibration accelerated salt corrosion simulation test

2.3.1 Preparation of salt solution

According to existing research findings: Ruiguang (2020) adopted a 5% concentration salt solution to immerse asphalt, exploring the evolution law of asphalt performance under salt erosion; Liang S. et al. (2024) incorporated chloride salt solutions with mass fractions ranging from 0% to 10% into asphalt mixtures, systematically analyzing the influence of chloride salt concentration on the interfacial bonding characteristics between asphalt and aggregates; Su et al. (2024) selected 5%, 10%, and 15% (mass percentage) as key test parameters to compare the erosion effects of different salt solution concentrations. Although the saltwater concentration along coastal shorelines varies, it generally ranges from 3% to 5%. Considering that this study aims to simulate the actual service environment of asphalt pavements in coastal areas and the most unfavorable salt erosion conditions, a 5% concentration NaCl solution was ultimately used to conduct indoor vibration-accelerated Salt-induced degradation tests.

2.3.2 Vibration acceleration simulated salt corrosion test parameters

Salt-induced degradation of asphalt pavement is a collective manifestation of the interaction of many factors. If only a single factor is considered, the actual situation cannot be reflected. If all factors are taken into account, the test conditions do not allow it. Therefore, this study will set the variables that mainly affect salt-induced degradation as constants according to the most unfavorable conditions to facilitate the conduct of the experiment and achieve the purpose of this study. Therefore, the erosion temperature was set to 30 °C. When the vehicle speed was 60–65 km/h (Ruiguang, 2020), the corresponding vibration frequency was 10 Hz. Therefore, in this test, the specimens were eroded at a vibration frequency of 10 Hz. The erosion time was set to 30 days.

2.3.3 Asphalt salt corrosion simulation test method

This study used the immersion method to simulate salt spray erosion, using meteorological standards to define salt spray conditions (visibility <1 km, humidity >90%). The specific method, as shown in Figure 6, involved preparing a (20 × 20 × 1) mm asphalt sheet, curing it at 5 °C, and then placing it in a 5% NaCl solution. The sheet, along with Marshall specimens and rutting plates, was then immersed in the 5% NaCl solution at 30 °C and 10 Hz vibration for 30 days. Untouched SBS asphalt was used as a control to ensure data comparability.

2.4 Test method

2.4.1 Basic performance test

This study investigated the penetration, softening point, and viscosity of SBS asphalt and PPA/BF/SBS composite modified asphalt, both prior to and following salt-induced degradation.

2.4.2 Marshall stability test under water

A study was conducted to systematically examine the evolution of water stability in asphalt mixtures under salt-induced degradation conditions. Standard Marshall specimens were prepared using SBS asphalt and PPA/BF/SBS composite modified asphalt, and were subsequently subjected to salt erosion treatment following the precise parameters outlined in Section 2.3.2. The submerged Marshall specimen is shown in Figure 5.

Figure 5

Figure 5. Immersed Marshall specimen.

2.4.3 High temperature wheel pressure test

In this research, conventional rutting tests will be employed to assess the high-temperature stability of SBS asphalt mixtures and PPA/BF/SBS composite modified asphalt mixtures under salt corrosion. The procedure and specimens of the rutting test are illustrated in Figure 6.

Figure 6

Figure 6. Rutting test process and specimen.

2.4.4 Salt accumulation in mixture

This section characterizes the effectiveness of asphalt mixtures in resisting salt-induced degradation by measuring the difference in the mass of salt crystals within asphalt mixtures both prior to and following salt-induced degradation. First, according to the aforementioned test method for indoor immersion of asphalt mixture specimens in salt-induced degradation, the mass of Marshall and rutting plate specimens both prior to and following salt-induced degradation was measured. Second, the mass of salt accumulated both prior to and following salt-induced degradation was calculated using the salt accumulation Equation 1. Finally, the corresponding residual stability and dynamic stability were determined.

$m=m_b-m_a(1)$

Where: m—Cumulative mass of salt (g);

m_b—Specimen mass before salt attack (g);

m_a—Specimen mass after salt attack (g).

In order to avoid the error of test data caused by moisture after salt-induced degradation, dry the salt-eroded specimens in a 50 °C oven for 10 h, and then weighed and the salt accumulation of the mixture is calculated.

2.5 Molecule model construction and verification

2.5.1 Composite modified asphalt model

The molecular dynamics simulation was structured around three main components: the construction and optimization of the composite modified asphalt model, and the selection of an appropriate ensemble and force field, all aimed at analyzing the adhesion energy at the asphalt-aggregate interface under salt-induced degradation.

As a complex mixture, road asphalt is typically classified at the molecular level using the SARA four-component method (asphaltenes, saturates, resins, and aromatics). When constructing a composite modified asphalt model, a chemically treated BF molecular model and a PPA macromolecular model are first established. These are then combined with a base asphalt molecular model and blended in appropriate proportions to form a complete system. Research has shown that an SBS modified asphalt model constructed with a linear structure and a 4% mass fraction of base asphalt can be effectively applied to molecular simulation studies in salt-induced environments.

During the construction of the molecular model, the mass ratio of PPA to SBS asphalt was set to 1:100, while that of BF to SBS asphalt was maintained at 3:100. Based on the AAA-1 asphalt model (Li and Greenfield, 2013), a representative model was constructed for the salt erosion tests in this study. The model comprises three asphaltene, five resin, two saturates, and two aromatics molecules. Their detailed molecular information is presented in Table 2, and the molecular configurations are shown in Figure 7.

Table 2

Table 2. Molecular information of each component of matrix asphalt.

Figure 7

Figure 7. Molecular structures of typical components in asphalt: Asphaltenes, Resins, Saturates, Aromatics, and additives (SBS, PPA, BF celluloses).

The accuracy of the molecular dynamics modeling method and force field parameters was validated by measuring the temporal density evolution of the composite modified asphalt model. This study used the equilibrium density at 298 K and 1 atm as an indicator and compared the simulation results with reference values from the literature. The results showed that the simulated density value was 1.022 g/cm³, which falls within 5% error of the reference range of 1.0–1.04 g/cm³ reported in Reference (Luo et al., 2020), indicating excellent agreement. This demonstrates that the simulated structure of the composite modified asphalt closely resembles that of real asphalt molecules, confirming the rationality and authenticity of the model.

2.5.2 Construction of the composite modified asphalt-salt solution-aggregate interface model

In this study, a three-layer interface model consisting of composite modified asphalt–salt solution–aggregate was established. Silica (SiO₂) was selected as the representative aggregate, and its surface was hydroxylated to simulate the real hydrated state. The unit cell parameters of SiO₂ are presented in Table 3, adopting the P3221 space group and a simple hexagonal lattice. The models of sodium chloride (NaCl) and aggregate are shown in Figure 8. The interface model is composed of three layers from top to bottom: the composite modified asphalt layer, the salt solution layer (or pure water layer), and the SiO₂ aggregate substrate. The salt solution was a 5% NaCl solution (containing 200 water molecules, 4 Na⁺ ions, and 4 Cl^- ions), while the pure water model consisted of 200 water molecules. A 30 Å vacuum layer was set above the asphalt layer, and the bottom 10 Å of aggregate atoms were fixed to eliminate the influence of periodic boundaries and maintain structural stability. After model construction, the system underwent energy minimization and annealing treatment under the NVT ensemble to remove initial stresses, followed by NVT equilibrium simulation to achieve a thermodynamic equilibrium state for the entire interface system.

Table 3

Table 3. The unit cell constants of SiO₂.

Figure 8

Figure 8. Aggregate and NaCl solution molecula rmodel (a) NaCl solution model; (b) Aggregate model.

The composite modified asphalt, salt solution (5.0% NaCl), and SiO₂ aggregate models were assembled into a layered structure according to Figure 9. To prevent periodic interference, a 30 Å vacuum layer was placed above the asphalt layer, and atoms within a 10 Å thickness of the aggregate substrate were fixed to form a stable interface model. The model was configured into three distinct architectures: a salt solution layer (NaCl), a pure water layer (Water), and a dry layer (Dry). Energy minimization was performed on each configuration for comparative analysis.

Figure 9

Figure 9. Schematic diagram of composite modified asphalt-salt solution-aggregate interface model construction.

During the production and operation phase, the COMPASS force field was employed to describe the interatomic interactions, and the Verlet algorithm was adopted for solving the equations of motion with a time step set to 1 fs. The simulations were primarily performed under the NVT ensemble, with the temperature controlled at 298 K using the Nosé–Hoover thermostat. The total simulation time was typically 500–1,000 ps, during which the system energy and configuration data were collected every 1 ps, and trajectory files were output periodically for subsequent analysis. After the simulations, the adhesion energy between asphalt and aggregate was calculated under dry, pure water, and salt solution environments. Furthermore, the contribution of interactions between each asphalt component and the aggregate was analyzed in detail, thereby revealing the variation mechanism of the interfacial adhesion performance of composite modified asphalt under salt erosion environments at the molecular scale.

2.5.3 Adhesion energy calculation

This study utilizes adhesion energy to characterize the interfacial adhesion properties between the composite modified asphalt and SiO₂ aggregate, thereby achieving a quantitative assessment of the bonding performance between them. The formula for calculating the interfacial adhesion energy under dry conditions is given as Equation 2

$E_{\text{ahesion}}=\frac{E_{as-agg}}{A}=\frac{\left(E_{asphalt}+E_{aggragats}\right)-E_{total}}{A}(2)$

Where: $E_{\text{ahesion}}$—Adhesion energy between asphalt and aggregate

$E_{asphalt}$—Potential energy of asphalt

$E_{aggragats}$—Potential energy of aggregate

$E_{total}$—Total potential energy between asphalt and aggregate

$E_{as-agg}$—Interaction force between asphalt and aggregate

A—Interfacial contact area

Since the PPS/BF/SBS composite modified asphalt model was constructed with reference to the four-component system analysis method, it is essential to consider the contributions of these components (asphaltenes, aromatics, saturates, and resins) to the interfacial adhesion energy between the composite modified asphalt and the aggregate. The intermolecular interaction forces and adhesion energy within the composite modified asphalt mixture system at the molecular scale, as well as the adhesion forces between each component and the aggregate, are detailed in Equation 3 and Equation 4. Equation 4 takes asphaltenes as an example to illustrate the interaction energy between asphaltene components and aggregates. The calculations of the interaction energy between the remaining components (resins, aromatics, and saturates) and aggregates are performed following the same approach as Equation 4.

$E_{asphalt}=E_{As}+E_{\text{Re}}+E_{Ar}+E_{Sa}(3)$

${\Delta E}_{As-agg}=E_{total\left(As+agg\right)}-\left(E_{As}+E_{aggregate}\right)(4)$

Where: E_As—Potential energy of asphaltene

E_Re—Potential energy of resin

E_Ar—Potential energy of aromatic fraction

E_Sa—Potential energy of saturate fraction

${\Delta E}_{As-agg}$—The interaction energy between asphaltene and aggregate

$E_{total\left(As+agg\right)}$—Total potential energy between the asphaltene component and the aggregate

3 Results and analysis

3.1 Fundamental properties of asphalt

3.1.1 Penetration

Penetration tests at 25 °C were carried out on neat SBS and PPA/BF/SBS composite modified asphalts, under both pre- and post-salt erosion conditions, with Figure 10 presenting the outcomes.

Figure 10

Figure 10. Penetration test results.

As shown in Figure 10, prior to salt-induced degradation, the penetration of the PPA/BF/SBS composite modified asphalt was generally lower than that of the SBS asphalt. At a fixed BF content of 3%, the penetration consistently decreased with increasing PPA content, indicating a significant influence of PPA dosage on penetration. The three PPA/BF/SBS composite modified asphalt exhibited notable differences in the extent of reduction: the largest decrease was observed for 1.5% PPA +3% BF (10.4 mm), the smallest for 0.5% PPA +3% BF (2.6 mm), and an intermediate value for 1.0% PPA +3% BF (5.9 mm). The underlying reasons may be attributed to the following aspects: first, the addition of BF improves the consistency of the asphalt; second, PPA promotes the agglomeration of asphaltenes and strengthens molecular cross-linking; third, PPA and SBS develop a spatially mutually interlocked configuration. Furthermore, the esterification of sulfoxide groups with PPA enhances the cohesion within the SBS, thereby reducing penetration and improving resistance to deformation.

After salt-induced degradation, the penetration of the PPA/BF/SBS composite modified asphalt further decreased; however, the SBS asphalt exhibited the largest reduction, with a decrease of 9.7 mm. Among the three PPA/BF/SBS composite modified asphalts, the reductions for the 1.5% PPA +3% BF, 0.5% PPA +3% BF, and 1.0% PPA +3% BF formulations were 8.9 mm, 5.7 mm, and 3.8 mm, respectively.

After salt-induced degradation, the penetration of the PPA/BF/SBS composite modified asphalt was further reduced. In contrast, the SBS asphalt showed the most significant decrease, with a reduction of 9.7 mm. Among the three types of PPA/BF/SBS composite modified asphalts, the decreases for the 1.5% PPA, 0.5% PPA, and 1.0% PPA were 8.9 mm, 5.7 mm, and 3.8 mm, respectively. These results indicate that the PPA content not only influences the magnitude of penetration change but also mitigates the performance degradation caused by salt-induced degradation. This effect can be attributed to the cross-linking interaction between PPA and SBS, the formation of a spatially interlocked structure, and chemical reactions, which collectively contribute to the development of a “hardened film” on the asphalt surface, thereby enhancing its resistance to salt-induced degradation.

3.1.2 Softening point

Softening point tests were performed on both the SBS asphalt and PPA/BF/SBS composite modified asphalt. The results are presented in Figure 11.

Figure 11

Figure 11. Softening point test results.

As shown in Figure 11, prior to salt-induced degradation, the softening points of the three PPA/BF/SBS composite modified asphalts were significantly higher than that of the SBS asphalt. The formulation with 1.5% PPA +3% BF exhibited the greatest increase, reaching approximately 17.6%; followed by 1.0% PPA +3% BF with an improvement of about 16.1%; and 0.5% PPA +3% BF showed the smallest enhancement, at around 15.2%. These results indicate that, under the same 3% BF content, The PPA notably elevated the softening point of the asphalt, and this effect became more pronounced with higher PPA dosage. This further demonstrates that, at the equivalent temperature, the PPA/BF/SBS composite modified asphalt shows remarkably enhanced deformation resistance when compared with the SBS asphalt.

After salt-induced degradation, the softening points of both the SBS asphalt and the three PPA/BF/SBS composite modified asphalts increased. Among them, the SBS asphalt exhibited the most notable change, showing a rise of 10.5 °C. This may be attributed to salt-induced degradation accelerating the evaporation of light components and the crystallization of salts leading to surface hardening. In contrast, the three PPA/BF/SBS composite modified asphalts exhibited smaller increases in softening point, which can be ascribed to the interaction between PPA and SBS: on one hand, it enhances molecular cross-linking, and the PPA/BF/SBS composite modified asphalt not only enhances crosslinking but also develops a protective hardened layer on the surface. This layer significantly mitigates salt-induced degradation. Experimental findings demonstrate that the PPA/BF/SBS composite modified asphalt offers superior durability against salt-induced degradation than the SBS asphalt.

3.1.3 Viscosity

In this research, viscosity measurements were carried out on both the SBS asphalt and the PPA/BF/SBS composite modified asphalt. The respective findings are presented in Figure 12.

Figure 12

Figure 12. Viscosity test results (135 °C).

As shown in Figure 14, prior to salt-induced degradation, the viscosity of the three PPA/BF/SBS composite modified asphalts increased with rising PPA content under a fixed BF dosage, all exceeding that of the SBS asphalt. The most significant viscosity increase was observed in the 1.0% PPA +3% BF formulation, which rose by approximately 21.6%, while the smallest increase still reached 8%. This indicates that the incorporation of both PPA modifier and BF significantly enhances the viscosity of the PPA/BF/SBS composite modified asphalt. Nevertheless, after salt-induced degradation, the viscosity of both the pristine SBS asphalt and the three composite modified asphalts declined. The SBS asphalt experienced the largest reduction, amounting to 19.8%, which may be attributed to a decrease in consistency caused by the erosion from the salt solution. In contrast, the PPA/BF/SBS composite modified asphalts showed smaller declines in viscosity. The smallest reduction was observed in the 1.0% PPA +3% BF formulation, which decreased by only 9%, significantly less than that of the salt-eroded pristine SBS asphalt. These results demonstrate that the PPA/BF/SBS composite modified asphalt exhibits considerably greater resistance to erosion by salt solution

Generally, asphalt and modified asphalt with high adhesion performance exhibit higher softening points, along with lower penetration and ductility (Loeber et al., 1998; Lesueur, 2008). However, the changes in the three major indicators observed in this study for the PPA/BF/SBS composite modified asphalt deviate from the conventional pattern. This suggests that both the PPA chemical modifier and BF have altered the overall colloidal structure of the asphalt. Furthermore, it indicates that such modifications in colloidal structure can lead to significant changes in the test results of the fundamental properties of asphalt (Baldino et al., 2013). In terms of fundamental performance, the PPA/BF/SBS composite modified asphalt demonstrates superior resistance to salt-induced degradation compared to the SBS asphalt, with the optimal formulation identified as 1.0% PPA +3% BF.

3.2 Moisture stability

The test results of the immersion Marshall test on asphalt mixtures are shown in Figure 13. Salt-induced degradation significantly affects the residual stability of asphalt mixtures. After salt-induced degradation, the residual stability of the pristine SBS mixture decreased by 9.4%, indicating a reduction in moisture damage resistance. In contrast, the composite modified mixture with 1.0% PPA +3% BF showed a decrease of only 4.3%, demonstrating its superior resistance to salt-induced degradation. Furthermore, the results indicate that the composite modification not only enhances the residual stability of the SBS mixture (remaining as high as 91.2% even after salt-induced degradation) but also yields higher values both both prior to and following salt-induced degradation compared to the pristine SBS mixture (85.7% before erosion). This confirms its more stable resistance to moisture damage in saline environments.

Figure 13

Figure 13. Asphalt residual stability.

Based on the microstructural analysis illustrated in Figure 14, the PPA/BF/SBS composite modified asphalt (1.0% PPA +3% BF) demonstrates significantly enhanced resistance to salt-induced degradation compared to the SBS asphalt. The underlying mechanism can be attributed to the following two aspects: Firstly, the incorporation of PPA facilitates the formation of a “hardened film” on the asphalt surface, which effectively blocks salt intrusion and reduces the penetration of saline solution. Concurrently, PPA promotes the agglomeration of asphaltenes and strengthens intermolecular cross-linking, thereby increasing the viscosity of the asphalt. Secondly, the chemically modified BF, with its rough surface, provides additional bonding sites for the asphalt, facilitating the formation of a stable three-dimensional network structure. This helps to reduce initial microcracks within the mixture. Consequently, the synergistic effect of PPA and BF results in a mere 4.3% decrease in residual stability for the PPA/BF/SBS composite modified asphalt under salt-induced degradation conditions, markedly improving its moisture stability. These findings are consistent with the results obtained from conventional performance tests.

Figure 14

Figure 14. Asphalt Surface Morphology: (a) SBS asphalt in the beaker. (b) 1.0%PPA+3%BF.

3.3 High-temperature stability (wheel tracking test)

The high-temperature stability of both the SBS asphalt mixture and the PPA/BF/SBS composite modified asphalt mixture under salt-induced degradation conditions was evaluated using the conventional wheel tracking test. The test results of these mixtures, both prior to and following salt-induced degradation, are presented in Figure 15.

Figure 15

Figure 15. Dynamic stability of asphalt.

The experimental results indicate that salt-induced degradation significantly reduces the high-temperature performance of asphalt mixtures. The dynamic stability of the SBS asphalt mixture decreased by 53.6%, whereas that of the 1.0% PPA +3% BF composite modified asphalt decreased by only 23.8%. Moreover, the dynamic stability of the PPA/BF/SBS composite modified asphalt mixture after salt-induced degradation (7,436.28 cycles/mm) remained higher than that of the pristine SBS mixture before erosion (7,032.48 cycles/mm). This improvement can mainly be ascribed to the “hardened film” structure formed in the PPA/BF/SBS composite modified asphalt, which not only effectively blocks the penetration of salt but also reduces the thermal sensitivity of the material. As a result, the PPA/BF/SBS composite modified asphalt exhibits superior and more stable high-temperature performance under salt-induced degradation conditions. This conclusion is consistent with the results obtained from conventional performance tests.

3.4 Correlation of salt accumulation

The salt accumulation was calculated using Equation 1, while the residual stability and dynamic stability were measured experimentally. To eliminate interference from moisture, the specimens were dried at 50 °C for 10 h before weighing and testing (results are shown in Table 4). Salt crystals, observed as white circular spots through high-contrast imaging (Figure 16), visually demonstrate the distribution of salt within the mixture.

Table 4

Table 4. Salt accumulation mass and corresponding IRS, DR.

Figure 16

Figure 16. Macroscopic diagram of salt accumulation (a) Salt particles inside the PPA/BF/SBS composite modified asphalt fragment; (b) Salt particles (whitedots) inside SBS original asphalt fragments.

Based on the data in Table 4 and the macroscopic morphology in Figure 16, it can be observed that the salt accumulation is consistently lower in the composite modified asphalt mixture (1.0% PPA +3% BF) than in the SBS asphalt mixture, for both wheel-tracking slabs and Marshall specimens. This suggests that the PPA/BF/SBS composite modified asphalt mixture exhibits superior resistance to erosion by salt solutions in contrast to the SBS mixture. However, the measurement of salt accumulation is relatively complex and prone to significant errors. Therefore, it is necessary to explore correlated indicators that can effectively characterize the resistance of asphalt mixtures to salt-induced degradation.

As indicated by the data above, variations in salt accumulation significantly affect both the moisture stability (residual stability) and high-temperature stability (dynamic stability) of asphalt mixtures. Both properties exhibit a decreasing trend with increasing salt accumulation, indicating that either can serve as an indicator of resistance to salt-induced degradation. However, to conserve experimental materials and reduce testing time, this section will perform a correlation analysis between salt accumulation and the moisture stability and high-temperature stability of the PPA/BF/SBS composite modified asphalt mixture after salt-induced degradation. The aim is to identify the indicator most closely correlated with salt accumulation for evaluating the effectiveness of salt-induced degradation resistance in asphalt mixtures.

Based on the experimental data in Table 4, a correlation analysis was conducted between the high-temperature stability and moisture stability of the PPA/BF/SBS composite modified asphalt mixture after salt-induced degradation. The results are shown in Figure 17.

Figure 17

Figure 17. Correlation analysis between salt accumulation and water stability and high temperature stability (a) water stability; (b) high temperature stability.

Based on the analysis of salt accumulation in Figure 19, the correlation coefficient between salt accumulation and high-temperature stability (0.902) is higher than that with moisture stability (0.891), indicating that salt-induced degradation has a more pronounced damaging effect on high-temperature performance. Therefore, monitoring changes in high-temperature stability can effectively assess the extent of salt accumulation and the mixture’s resistance to salt-induced degradation.

Data analysis reveals that as salt accumulation increases, both the Immersed Residual Stability (IRS) and Dynamic Stability (DS) of the specimens show a declining trend, with DR decreasing more markedly. This suggests that salt-induced degradation is a continuous degradation process. The underlying mechanism lies in the repeated crystallization and dissolution of salt within the mixture, which disrupts structural integrity under the combined action of traffic loading and hydrodynamic pressure. High-temperature conditions further accelerate the cycle of salt crystallization and dissolution, leading to a more rapid decline in high-temperature stability compared to moisture stability.

3.5 Analysis of adhesion energy

The simulation results of the adhesion energy between the PPA/BF/SBS composite modified asphalt and aggregate are shown in Figure 18.

Figure 18

Figure 18. Adhesion energy between asphalt and aggregate.

The experimental results indicate that the adhesion performance between the PPA/BF/SBS composite modified asphalt and aggregate exhibited a consistent decreasing trend across the three environmental conditions: dry > pure water > salt solution. However, it consistently outperformed the SBS asphalt. Quantitative analysis revealed that in a pure water environment, the adhesion energy of the SBS and PPA/BF/SBS composite modified asphalts decreased by 51.9% and 46.4%, respectively, compared to dry conditions. Under salt solution conditions, the reductions were further amplified to 60.4% and 52.4%. These findings demonstrate that moisture is a critical factor affecting interfacial adhesion, while the presence of salt exacerbates the degradation of adhesion performance by accelerating the interfacial debonding process. It is noteworthy that the PPA/BF/SBS composite modified asphalt demonstrated superior performance across all tested environments, with its advantage over the pristine SBS asphalt being particularly pronounced under salt-induced degradation conditions. This robustly confirms the enhanced salt-induced degradation resistance of the PPA/BF/SBS composite modified asphalt. These findings provide an important theoretical foundation for the application of modified asphalt materials in salt-affected environments.

The interaction results between various components of the PPA/BF/SBS composite modified asphalt and the aggregate are shown in Figure 19.

Figure 19

Figure 19. Adhesion energy between asphalt components and aggregate (a) Asphaltene; (b) Aromatic; (c) Saturates; (d) Resin.

The research data indicate that the adhesion energy between the components of the PPA/BF/SBS composite modified asphalt and the aggregate follows the order: resins > aromatics > asphaltenes > saturates. Among these, resins and aromatics are the key components influencing the adhesion performance, contributing the majority of the overall adhesion energy. It is noteworthy that the adhesion energy of asphaltenes, resins, and saturates in the PPA/BF/SBS composite modified asphalt is consistently higher than that in the SBS asphalt. This can be primarily attributed to the cyclization effect of PPA, which converts a portion of resins into asphaltenes, thereby enhancing the overall adhesion performance.

The experimental results demonstrate that under both pure water and salt solution environments, the reduction in adhesion energy for each component of the PPA/BF/SBS composite modified asphalt was consistently smaller than that of the SBS asphalt. Specifically, in the pure water environment, the adhesion energy of the four components (asphaltenes, aromatics, saturates, and resins) of the PPA/BF/SBS composite modified asphalt decreased by 40.0%, 46.9%, 22.7%, and 34.6%, respectively, whereas the SBS asphalt exhibited decreases of 55.9%, 62.6%, 45.5%, and 47.8%. In the salt solution environment, the reductions for the PPA/BF/SBS composite modified asphalt were 53.3%, 35.9%, 16.0%, and 26.1%, while those for the SBS asphalt were as high as 69.1%, 56.1%, 63.6%, and 39.1%. These data robustly confirm the superior salt-induced degradation resistance of the PPA/BF/SBS composite modified asphalt.

It is particularly noteworthy that, due to its non-polar nature, the saturate fraction contributed adhesion energy below 12 kcal/mol under all environmental conditions, and its content was not significantly influenced by PPA. This finding further confirms the dominant role of resins and aromatics in enhancing the adhesion performance of asphalt.

4 Conclusion

To enhance resistance to marine salt-induced degradation and promote the high-temperature performance and the resistance to water damage of SBS asphalt, this study devised an indoor vibration-accelerated simulation test for salt-induced degradation of asphalt mixtures. Furthermore, molecular dynamics simulations were performed to explore the adhesion characteristics between asphalt and aggregate in various solution environments. The primary conclusions are as follows:

1. Both the PPA/BF/SBS composite modified asphalt and the SBS asphalt saw an increase in softening point and viscosity after salt-induced degradation, whereas the penetration and ductility declined markedly. The PPA/BF/SBS composite modified asphalt demonstrated superior salt-induced degradation resistance compared to the SBS asphalt, and the optimal dosage was determined to be 1.0% PPA +3% BF.

2. Salt-induced degradation reduces the moisture stability of asphalt mixtures. However, the PPA/BF/SBS composite modified asphalt mixture demonstrated a stronger resistance to salt-induced degradation compared to the SBS asphalt mixture, maintaining a higher residual stability both prior to and following salt-induced degradation.

3. The salt accumulation within the asphalt mixture negatively correlates with both moisture stability and high-temperature stability. Moreover, the influence of salt accumulation on high-temperature stability is more pronounced than its effect on moisture stability.

4. Molecular dynamics simulations reveal that the presence of interfacial water weakens the adhesive performance between asphalt and aggregate, while the presence of salt solution further exacerbates interfacial debonding. Compared to the SBS asphalt, the PPA/BF/SBS composite modified asphalt exhibits a higher retention rate of adhesion energy under both wet and salt-induced degradation conditions, confirming its superior resistance to moisture-induced damage and salt-induced degradation.

Data availability statement

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

Author contributions

KH: Conceptualization, Funding acquisition, Methodology, Writing – review and editing. JW: Writing – review and editing, Formal Analysis, Methodology, Validation. XL: Writing – review and editing, Data curation, Investigation, Supervision. HN: Writing – original draft, Writing – review and editing. YX: Formal Analysis, Project administration, Visualization, Writing – review and editing. LH: Data curation, Supervision, Validation, Writing – review and editing.

Funding

The author(s) declared that financial support was received for this work and/or its publication. The research was supported by 2022 Key Science and Technology Projects for the Transportation Industry of the Ministry of Transportation of China (Project No. 2022.ZD7-130). The Nanning South Transit Line (from Liujing to Datang Section and fromWuxu Airport to Long’an Extension Section) Highway Scientific Research Topic (Project·No. EHGS-GC-2023-025).

Conflict of interest

Authors KH and WJ were employed by Guangxi Nanning Second Ring Expressway Co., Ltd. Author XL was employed by Nanning Expressway Construction & Development Co., Ltd.

The remaining author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

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References

Ahmed, K. U., Geremew, A., and Jemal, A. (2022). The comparative study on the performance of bamboo fiber and sugarcane bagasse fiber as modifiers in asphalt concrete production. Heliyon 8, e09842. doi:10.1016/j.heliyon.2022.e09842

PubMed Abstract | CrossRef Full Text | Google Scholar

Aliha, M. R. M., Razmi, A., and Mansourian, A. (2017). The influence of natural and synthetic fibers on low temperature mixed mode I plus II fracture behavior of warm mix asphalt (WMA) materials. Eng. Fract. Mech. 182, 322–336. doi:10.1016/j.engfracmech.2017.06.003

CrossRef Full Text | Google Scholar

Anandaraj, S., Karthik, S., Sylesh, S., Kishor, R., Suresh, K., Prakash, K. J., et al. (2023). Experimental investigation on sugarcane bagasse fiber reinforced concrete using bottom ash as sand replacement. Mater. Today Proc. doi:10.1016/j.matpr.2023.03.469

CrossRef Full Text | Google Scholar

Baldino, N., Gabriele, D., Lupi, F. R., Rossi, C. O., Caputo, P., and Falvo, T. (2013). Rheological effects on bitumen of polyphosphoric acid (ppa) addition. Constr. Build. Mater. 40, 397–404. doi:10.1016/j.conbuildmat.2012.11.001

CrossRef Full Text | Google Scholar

Gang, D. (2018). Performance and mechanism analysis of polyphosphoric acid and polyphosphoric acid/polymer composite modified asphalt. Xi'an: Chang'an University.

Google Scholar

Gao, Y., Yu, X., Fan, X., Zhang, H., Xia, Q., Zhou, Z., et al. (2025). Evaluation of adhesion performance and molecular dynamics simulation of SBS–modified asphalt during the field aging. Constr. Build. Mater. 474, 141116. doi:10.1016/j.conbuildmat.2025.141116

CrossRef Full Text | Google Scholar

Jiao, X., Huang, D., Zhao, S., and Ouyang, J. (2024). Study on the compatibility of SBR and asphalt base based on molecular simulation. Materials 17, 1175. doi:10.3390/ma17051175

PubMed Abstract | CrossRef Full Text | Google Scholar

Lesueur, D. (2008). The colloidal structure of bitumen: consequences on the rheology and on the mechanisms of bitumen modification. Adv. Colloid. Interface. Sci. 145, 42–82. doi:10.1016/j.cis.2008.08.011

PubMed Abstract | CrossRef Full Text | Google Scholar

Li, D. D., and Greenfield, M. L. (2013). Chemical compositions of improved model asphalt systems for molecular simulations. Fuel 115, 347–356. doi:10.1016/j.fuel.2013.07.012

CrossRef Full Text | Google Scholar

Li, Z. Z., Li, K., Chen, W. X., Liu, W. D., Yin, Y. P., and Cong, P. L. (2022). Investigation on the characteristics and effect of plant fibers on the properties of asphalt binders. Constr. Build. Mater. 338, 127652. doi:10.1016/j.conbuildmat.2022.127652

CrossRef Full Text | Google Scholar

Li, J., Yang, L., He, L., Guo, R., Li, X., Chen, Y., et al. (2023). Research progresses of fibers in asphalt and cement materials: a review. J. Road Eng. 3, 35–70. doi:10.1016/j.jreng.2022.09.002

CrossRef Full Text | Google Scholar

Li, S., Xu, H., Shi, H., and Bian, X. (2025). Pore water pressure dynamic response in asphalt mixture: a measurement system development. Measurement 242, 115882. doi:10.1016/j.measurement.2024.115882

CrossRef Full Text | Google Scholar

Li, Z., Huang, Z., Xiong, Q., Liu, W., You, Z., Huang, Y., et al. (2025). Effect of hygrothermal environment on properties of bagasse fibers and asphalt binders/mixtures with bagasse fibers. Constr. Build. Mater. 465, 140242. doi:10.1016/j.conbuildmat.2025.140242

CrossRef Full Text | Google Scholar

Liang, B., Liao, W., and Zheng, J. (2024). Review on molecular dynamics simulation for compatibilities of modifiers with asphalt. J. Traffic Transp. Eng. 24, 54–85. doi:10.19818/j.cnki.1671-1637.2024.05.005

CrossRef Full Text | Google Scholar

Liang, S., Liang, C., Li, M., Cui, H., Wang, Z., and Wang, S. (2024). Investigation of nanoscale interfacial bonding properties in foamed asphalt cold recycled mixtures under chloride salt erosion. Case Stud. Constr. Mater. 21, e03390. doi:10.1016/j.cscm.2024.e03390

CrossRef Full Text | Google Scholar

Liu, H., Zhang, M., Huang, L., Chang, R., and Hao, P. (2016). Rheological and anti-aging properties of polyphosphoric acid composite styrene butadiene styrene modified asphalt. J. Southeast Univ. Nat. Sci. Ed. 46, 1290–1295. doi:10.3969/j.issn.1001-0505.2016.06.030

CrossRef Full Text | Google Scholar

Loeber, L., Muller, G., Morel, J., and Sutton, O. (1998). Bitumen in Colloid science: a chemical, structural and rheological approach. Fuel 77, 1443–1450. doi:10.1016/s0016-2361(98)00054-4

CrossRef Full Text | Google Scholar

Luo, R., Shi, H., Teng, W., and Song, C. (2017). Prediction of wheel profile wear and vehicle dynamics evolution considering stochastic parameters for high-speed train. Wear 392-393, 126–138. doi:10.1016/j.wear.2017.09.019

CrossRef Full Text | Google Scholar

Luo, L., Chu, L., and Fwa, T. F. (2020). Molecular dynamics analysis of moisture effect on asphalt-aggregate adhesion considering anisotropic mineral surfaces. Appl. Surf. Sci. 527, 146830. doi:10.1016/j.apsusc.2020.146830

CrossRef Full Text | Google Scholar

Ma, F., Wen, Y., Fu, Z., Feng, Q., Jin, Y., and Guo, X. (2021). Pavement performance of PPA composite modified asphalt mixture. Appl. Chem. Ind. 50, 887–891. doi:10.16581/j.cnki.issn1671-3206.20210127.023

CrossRef Full Text | Google Scholar

Mansor, S., Zainuddin, N. I., Aziz, N. A., Razali, M., and Joohari, M. I. (2018). Sugarcane bagasse fiber - an eco-friendly pavement of SMA in Advances in civil engineering and science technology Editors L. D. Goh, K. S. Ng, S. H. Hassan, Y. P. Woo, M. Basri, and M. Hamid International Conference on Advances in Civil Engineering and Science Technology (ICACEST).

Google Scholar

Meneses, J., Teixeira, J., Alvarez, A. E., Aragao, F., and Fritzen, M. A. (2021). Exploratory study on the addition of sugarcane bagasse fibers to permeable friction course mixtures. J. Mater. Civ. Eng. 33, 04021241. doi:10.1061/(ASCE)MT.1943-5533.0003849

CrossRef Full Text | Google Scholar

Meng, Y., Li, H., Yang, X., Li, G., Li, Y., and Xu, G. (2025). Study on the adhesion properties of SBS modified asphalt-aggregate with polyphosphoric acid and sugarcane bagasse fiber under salt erosion. Constr. Build. Mater. 466, 140269. doi:10.1016/j.conbuildmat.2025.140269

CrossRef Full Text | Google Scholar

Ruibo, R., Jian, B., Pinhui, Z., Fankai, L., and Zhengnan, Z. (2020). Progress in molecular dynamics simulation of asphalt materials. J. Shandong Jianzhu Univ. 35, 61–68. doi:10.12077/sdjz.2020.03.010

CrossRef Full Text | Google Scholar

Ruiguang, X. (2020). Study on the effect of sodium erosion onasphalt self-healing and fatigue performance. Nanning: Guangxi University.

Google Scholar

Sharma, A., Choudhary, R., and Kumar, A. (2024). Laboratory investigation of draindown behavior of open-graded friction-course mixtures containing banana and sugarcane bagasse natural fibers. Transp. Res. Rec. 2678, 366–380. doi:10.1177/03611981231170875

CrossRef Full Text | Google Scholar

Shu, B. N., Wu, S. P., Dong, L. J., Norambuena-Contreras, J., Li, Y. Y., Li, C., et al. (2020). Self-healing capability of asphalt mixture containing polymeric composite fibers under acid and saline-alkali water solutions. J. Clean. Prod. 268, 122387. doi:10.1016/j.jclepro.2020.122387

CrossRef Full Text | Google Scholar

Su, B., Meng, Y., Hu, S., and Qin, Y. (2024). Study on self-healing performance of asphalt under sodium salt erosion. Case Stud. Constr. Mater. 20, e02921. doi:10.1016/j.cscm.2024.e02921

CrossRef Full Text | Google Scholar

Sun, H., Jin, Z., Yang, C., Akkermans, R. L. C., Robertson, S. H., Spenley, N. A., et al. (2016). COMPASS II: extended coverage for polymer and drug-like molecule databases. J. Mol. Model. 22. doi:10.1007/s00894-016-2909-0

PubMed Abstract | CrossRef Full Text | Google Scholar

Transport, R. I. O. H. (2004). Technical specifications for construction of highway asphalt pavements. Ind. Stand. - Transp.

Google Scholar

Transport, R. I. O. H. (2011). Standard test methods of asphalt and asphalt mixture forHighway engineering. Ind. Stand. - Transp.

Google Scholar

Transport, R. I. O. H. (2024). Test methods of aggregates for highway engineering. Ind. Stand. - Transp.

Google Scholar

Wang, L., Wang, Z., and Li, C. (2017). High temperature rheological properties of polyphosphoric acid modified asphalt. Acta Mater. Compos. Sin. 34, 1610–1616. doi:10.13801/j.cnki.fhclxb.20160921.001

CrossRef Full Text | Google Scholar

Wang, W., Wang, L., Miao, Y., Cheng, C., and Chen, S. (2020). A survey on the influence of intense rainfall induced by climate warming on operation safety and service life of urban asphalt pavement. J. Infrastructure Preserv. Resil. 1, 1496–1509. doi:10.1186/s43065-020-00003-0

CrossRef Full Text | Google Scholar

Wang, W., Luo, R., Li, J., and Wang, L. (2022). Evaluation on the influence of dynamic water pressure environment on viscoelastic mechanical performance of asphalt mixture using the bending beam rheometer method. Constr. Build. Mater. 321, 126428. doi:10.1016/j.conbuildmat.2022.126428

CrossRef Full Text | Google Scholar

Wang, Y., Li, D., Li, B., Wei, D., Tu, C., and Wei, X. (2024). Adhesion characteristics of polyphosphate SBS modified asphalt. J. Mater. Sci. Eng. 42, 578–586. doi:10.14136/j.cnki.issn1673-2812.2024.04.006

CrossRef Full Text | Google Scholar

Wang, W., Zhang, Q., Liang, J., Cheng, Y., and Jin, W. (2025). Mechanical performance of asphalt materials under salt erosion environments: a literature review. Polymers 17, 1078. doi:10.3390/polym17081078

PubMed Abstract | CrossRef Full Text | Google Scholar

Wu, S., Zhang, Y., Li, C., Chen, H., Zhang, H., and Kuang, D. (2020). Preparation and performance evaluation of SBS/PPA composite modified emulsified asphalt. Appl. Chem. Ind. 49, 1438–1442. doi:10.16581/j.cnki.issn1671-3206.20200330.017

CrossRef Full Text | Google Scholar

Xiang, L., Zhengwei, Z., Xiaolong, Y., and Xiaolong, Z. (2017). Status Quo and future prospect of polyphosphoric acid modified asphalt. Mater. Rep. 31, 104–111. doi:10.11896/i.issn.1005-023X.2017.019.015

CrossRef Full Text | Google Scholar

Yalikun, N., Yu, S., Yang, H., Liu, C., Zhang, H., Wang, Q., et al. (2025). Preparation and performance study of oxidized CR/SBS composite modified asphalt. J. Environ. Chem. Eng. 13, 117094. doi:10.1016/j.jece.2025.117094

CrossRef Full Text | Google Scholar

Yang, X., Liu, G., Rong, H., Meng, Y., Peng, C., Pan, M., et al. (2022). Investigation on mechanism and rheological properties of Bio-asphalt/PPA/SBS modified asphalt. Constr. Build. Mater. 347, 128599. doi:10.1016/j.conbuildmat.2022.128599

CrossRef Full Text | Google Scholar

Yang, L., Luo, W., Muhammad, Y., Meng, F., Li, J., Zhao, Z., et al. (2024). Surface modification of bagasse fibers based on polyphenol-induced self-supplied lignin for the creation of composite SBS-modified asphalt. Ind. Crop. Prod. 208, 117835. doi:10.1016/j.indcrop.2023.117835

CrossRef Full Text | Google Scholar

Zhou, Y., Zhang, K., Guo, Y., Yue, H., Wang, D., Peng, Z., et al. (2024). Effect of PPA composite modification on asphalt-aggregate adhesion and water stability. China J. Highw. Transp. 37, 317–330. doi:10.19721/j.cnki.1001-7372.2024.06.026

CrossRef Full Text | Google Scholar

Ziari, M. A., Hajikarimi, P., Kheirati Kazerooni, A., Moghadas Nejad, F., and Fini, E. H. (2021). Effect of polyphosphoric acid on fracture properties of asphalt binder and asphalt mixtures. Constr. Build. Mater. 310, 125240. doi:10.1016/j.conbuildmat.2021.125240

CrossRef Full Text | Google Scholar