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This study utilized molecular dynamics simulations to assess the rejuvenation of aged asphalt (AA) with waste soybean oil (WSO) and functionalized SBS polymers, focusing on: 1) constructing and validating models for virgin asphalt (VA), AA, and composite rejuvenated asphalt with WSO and polymers; 2) analyzing diffusion effects and binding abilities in these rejuvenated models; 3) evaluating interface binding and diffusion behaviors in composite rejuvenated models. The addition of functionalized SBS molecules and WSO improved the diffusion rates of various components within these models. Specifically, functionalized linear-SBS (LSBS) molecules demonstrated superior diffusion performance compared to star-SBS (SSBS) molecules. Incorporating WSO and polymers into the AA model increased the occupied volume of all rejuvenated models. The free volume fraction (FFV) in rejuvenated asphalt models exceeded that in AA at 433 K, suggesting that the inclusion of WSO and polymers enhances molecular mobility. As temperature increased, the interaction energy between polymers and asphalt components decreased. LSBS molecules exhibited stronger interactions with asphalt components than SSBS molecules, whose interaction energy was significantly enhanced by hydrogenation treatment. In rejuvenated-rejuvenated asphalt models, the interface interaction energy was higher than in VA–VA models, suggesting improved interface stability. However, diffusion rates of various components in rejuvenated-rejuvenated asphalt models were lower than those in VA–VA models. • The composite rejuvenated bitumen models of eight polymers molecules and waste soybean oil were constructed. • The diffusion rate, interaction energy and volume parameters of composite rejuvenated asphalt models were evaluated. • The interaction energy and diffusion rate of the asphalt-asphalt models were assessed. [ABSTRACT FROM AUTHOR]

Improving the poor long-term service performance of rejuvenated SBS-modified asphalt (REF-LT) is highly challenging. In this study, a blend of aged and virgin binders was used to rejuvenate REF-LT and the evolution of the asphalt performance was observed during regeneration and reaging processes. An SBS-modified asphalt (SBM) and base asphalt (BA) were mixed with REF-LT in specified ratios to prepare SBM- and BA-rejuvenated asphalts. The rejuvenated asphalts were subjected to short- and long-term aging. The high/low-temperature rheological properties, fatigue resistance, rejuvenation mechanism, and changes in the functional groups of the rejuvenated and reaged asphalts were characterized using a dynamic shear rheometer (DSR) and Fourier transform infrared spectroscopy (FTIR). The antiaging performance of the rejuvenated asphalt was evaluated. Temperature sweep results showed that both SBM and BA mitigated hardening in REF-LT. BA had a stronger softening effect on REF-LT than SBM. However, the BA-rejuvenated asphalt was more temperature sensitive than the SBM-rejuvenated asphalt. The BA-rejuvenated asphalt had poor resistance to reaging, whereas the SBM-rejuvenated asphalt demonstrated outstanding resistance to long-term aging. The Glover–Rowe (G-R) parameters indicated that after short-term aging, the rejuvenated asphalts remained in the no cracking zone, demonstrating outstanding resistance to thermal cracking. A total of 20 h of long-term aging of the rejuvenated asphalts decreased the crossover frequency and increased the rheological index, suggesting an increased risk of cracking. Relaxation tests showed that the BA-rejuvenated asphalt had a lower peak stress than that of the SBM-rejuvenated asphalt; however, the durability of the BA-rejuvenated asphalt was compromised because of the peak stress rapidly increased after reaging. Although the BA-rejuvenated asphalt exhibited good short-term crack resistance, its poor durability resulted in inferior thermal crack resistance to that of the SBM-rejuvenated asphalt after long-term aging. Linear amplitude sweep (LAS) tests indicated that the SBM-rejuvenated asphalt had a lower damage rate than the BA-rejuvenated asphalt, suggesting that the polymer network structure provided excellent damage resistance. The fatigue life of the BA-rejuvenated asphalt decreased considerably after reaging, indicating insufficient long-term fatigue resistance. The FTIR results indicated that the REF-LT rejuvenation process involved physical blending and the SBM-rejuvenated asphalt exhibited superior antiaging capability to the BA-rejuvenated asphalt. Increasing the BA content did not improve the long-term antiaging performance of the BA-rejuvenated asphalt. The higher antiaging performance of the SBM-rejuvenated asphalt resulted from the polymer network structure. • This study adopted a method of blending virgin and aged asphalt for the rejuvenation of aged SBS-modified asphalt. • BA demonstrates outstanding efficacy in restoring the short-term thermal cracking resistance of aged SBS-modified asphalt. • SBM-rejuvenated asphalt demonstrates excellent resistance to long-term reaging in comparison to BA-rejuvenated asphalt. [ABSTRACT FROM AUTHOR]

This study investigated the performance of SBS-modified bitumen (SBSMB) after aging and rejuvenation by utilizing macroscopic performance and microscopic characterization methodologies. The blending of aged SBS-modified bitumen (SBSPAV) with different proportions of SBSMB or 80–100 penetration grade base bitumen (90BB) was performed to produce SMB-rejuvenated bitumen (a blend of SBSMB and SBSPAV) and 90BB-rejuvenated bitumen (a blend of 90BB and SBSPAV). To evaluate high-temperature rutting behavior, multiple stress creep recovery (MSCR) tests were conducted on the binders, and the outcomes were analyzed using the Burgers model to elucidate their viscoelastic behaviors. Low-temperature performance was assessed using an asphalt binder cracking device (ABCD). Furthermore, the microscopic structure, roughness, and Young's modulus of the binders were investigated using an atomic force microscope (AFM). Thermal stability was assessed using a thermogravimetric analyzer (TGA). The findings indicated that SMB-rejuvenated bitumen exhibited favorable resistance to high temperatures and the ability to withstand heavy traffic loads. The stress sensitivity of 90BB-rejuvenated bitumen surpassed that of SMB-rejuvenated bitumen. The high-temperature performance rating of 90BB-rejuvenated bitumen displayed a continuous decline, indicating poor load-bearing capacity. Regardless of the unaged bitumen type, higher doses of unaged bitumen led to a gradual decrease in the rejuvenated bitumen's cracking temperature, indicating the enhancement of low-temperature performance of SBSPAV. However, both SMB-rejuvenated bitumen and 90BB-rejuvenated bitumen fell short of matching the performance level of pure SBSMB. AFM outcomes demonstrated that with increasing SMB dosage, the number of bee-like structures initially decreased before rising again, coupled with an increase in their volume. Conversely, an increase in 90BB dosage led to a gradual reduction in bee-like structures, accompanied by increased volume. The roughness of both SMB-rejuvenated bitumen and 90BB-rejuvenated bitumen exhibited improvements compared to SBSPAV, suggesting enhanced adhesion performance of the rejuvenated bitumen. TGA results unveiled lower thermal stability in 90BB-rejuvenated bitumen in comparison to SMB-rejuvenated bitumen. This study introduces a novel perspective on the design of SBS-rejuvenated bitumen. • The aged SBS-modified bitumen was rejuvenated by utilizing base bitumen and SBS-modified bitumen as additives. • The rutting resistance and cracking temperature of rejuvenated bitumen were accessed. • The microscopic morphology and thermal stability of rejuvenated bitumen were characterized. [ABSTRACT FROM AUTHOR]

In response to the growing demand for energy-efficient and sustainable materials in road construction, this research presents a pioneering method to enhance the engineering application of bio-oil rejuvenated asphalt. Initially, aged asphalt was rejuvenated by blending with 6% castor oil. Subsequent modifications included introducing varying concentrations of polyphosphoric acid (PPA) (0%, 0.5%, 1.0%, 1.5%), combined with differing sulfur levels (15% and 30%). The rheological properties of the resulting asphalt binders were assessed using rotational viscometer (RV), asphalt binder crack device (ABCD), and dynamic shear rheometer (DSR) tests, while fourier transform infrared spectroscopy (FTIR) test was employed to reveal the interaction mechanism. The study's key findings reveal that incorporating 15% sulfur significantly reduces asphalt viscosity, effectively lowering the mixing and compaction temperatures by approximately 17 °C and 15 °C, respectively. Besides, rutting factor ( G * / sin δ) and fatigue life (N f) results unveil a positive connection between PPA content, high-temperature stability, and fatigue resistance. Furthermore, the grey relational analysis emphasizes a strong correlation between G * / sin δ and R 3.2 (grey relational degree of 0.986), indicating that the recovery rate partially reflects high-temperature performance. The FTIR analysis demonstrates that bio-oil primarily contributes through physical blending, whereas PPA undergoes chemical transformations, and the combination of sulfur with asphalt results in both physical and chemical reactions. In conclusion, this research emphasizes the synergistic potential of bio-oil, sulfur, and PPA in enhancing recycled asphalt performance. For optimal warm mix efficiency and road performance, incorporation of 15% sulfur and 1.0% PPA in bio-rejuvenated asphalt is recommended. These findings provide substantial advantages in reducing reliance on petroleum asphalt and mitigating carbon emissions, contributing to sustainable infrastructure development. • Introduced a groundbreaking approach for rejuvenating aged asphalt. • Determined an ideal formulation of 15% sulfur and 1.0% PPA. • Demonstrated significant environmental advantages. [ABSTRACT FROM AUTHOR]

• Rheological properties of plasticizer/PPA modified asphalts are studied. • Plasticizer/PPA modified asphalt has better high and low temperature performance than base asphalt. • Plasticizer/PPA modified asphalt has good storage stability and the prepare process of it is simple. • The modification mechanism of plasticizer/PPA modified asphalt is revealed. Plasticizers have been proven to be effective in improving the low temperature flexibility of asphalt; however, plasticizer modified asphalts exhibit compromised high temperature stability. In this regard, polyphosphoric acid (PPA) may offer some advantages. This study aims to investigate the conventional properties, rheological behavior, thermal storage stability, and microstructure of plasticizer and PPA (plasticizer/PPA) modified asphalts. The experimental design comprises two plasticizers (dioctyl phthalate (DOP) and trioctyl trimelliate (TOTM)) and four PPA contents (0.5, 1, 1.5, and 2 wt%). The prepared plasticizer/PPA modified asphalts are examined by rotational viscometer, dynamic shear rheometer, bending beam rheometer, thermal storage, and Fourier transform infrared (FTIR) spectroscopy tests. The results show that the high temperature deformation resistance and elastic recovery ability of the plasticizer modified asphalts are effectively improved by the addition of PPA, and the improvement degree is positively correlated to the PPA content. PPA also has a beneficial effect on the low temperature performance of the plasticizer modified asphalts; however, the effect weakens with the PPA content increase. Moreover, the results of Analysis of Variance - Tukey's HSD analysis show that DOP/PPA and TOTM/PPA modified asphalts have significant difference in high and low temperature performance. The results of the thermal storage tests demonstrate that the plasticizer/PPA modified asphalts have excellent storage ability. The FTIR results show that the plasticizers are physically mixed with base asphalt, whereas there is a chemical reaction between PPA and the plasticizer modified asphalts. In general, the preparation process of plasticizer/PPA modified asphalts is simple and they have good comprehensive performance, which illustrate that combined plasticizer and PPA modification is a promising technology. [ABSTRACT FROM AUTHOR]

To investigate the fatigue and self-healing properties of aged and rejuvenated SBS-modified asphalt, soybean oil (SBO), epoxidized soybean oil (ESO), and commercial rejuvenators (LBS) were selected as asphalt rejuvenators. The fatigue performance of the asphalt was assessed through a time sweep procedure using a dynamic shear rheometer (DSR) instrument. Subsequently, a series of fatigue-healing-fatigue tests were conducted with varying healing times and damage degrees to analyze the self-healing characteristics of the asphalt. The rejuvenation and self-healing mechanisms were elucidated through a fluorescence microscope, Fourier transform infrared spectroscopy (FTIR), and thin-layer chromatography with flame ionization detection (TLC-FID) tests. The results revealed that the fatigue life of aged SBS asphalt deteriorated by more than 17% compared to unaged asphalt, and the self-healing properties were also weakened. However, both the fatigue life and self-healing properties could be significantly restored through the addition of rejuvenators, with SBO exhibiting the most pronounced effect in their restoration, followed by LBS and ESO. Furthermore, the self-healing capacity of the asphalt was notably affected by both the healing time and damage degree. Microstructure test results showed that in aged SBS-modified asphalt, lighter components dissipated, and the polymer deteriorated, contributing to the decline in self-healing performance. The presence of a substantial quantity of lightweight components in SBO expedited wetting and molecular diffusion at the damaged interface within the asphalt, thereby restoring the self-healing properties of the aged asphalt. • The anti-fatigue and self-healing properties of SBS-modified asphalt decrease after aging. • SBO has the best recovery effect on the self-healing properties of aged asphalt. • After aging, the structure of SBS polymer is damaged and the light components are reduced. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microcapsules with core–shell ratio of 1:2 exhibit excellent characteristics. • The content of microcapsules in asphalt should not be exceeds 3%. • The addition of microcapsules effectively enhances the self-healing properties of asphalt. The objective of this study was to prepare microcapsules and investigate their impact on the self-healing properties of asphalt. Microcapsules with various core–shell ratios were prepared by enveloping soybean oil with Melamine-Urea-Formaldehyde (MUF) resin through an in-situ polymerization method. The laser particle size analyzer, thermogravimetric analyzer, and scanning electron microscope were utilized to character the microcapsules and determined the optimal core–shell ratio. The rheological and self-healing performance of the microcapsule-modified asphalt were examined through frequency sweep, multi stress creep and recovery (MSCR), and Fatigue-Healing-Fatigue (F-H-F) tests conducted using a dynamic shear rheometer (DSR). The results indicate that microcapsules with various core–shell ratios exhibit uniform particle distribution and excellent thermal stability. Specifically, microcapsules with a core–shell ratio of 1:2 display a smooth appearance. The incorporation of microcapsules into asphalt impedes the flow of asphalt molecules and increases the initial flow temperature. When the microcapsules rupture, the released soybean oil modifies the rheological behavior of the asphalt, leading to a decrease in stress sensitivity and rutting resistance. Simultaneously, the remaining MUF resin imparts additional elastic recovery properties to the asphalt. The self-healing performance of microcapsule-modified asphalt was significantly enhanced, with a notable improvement observed as the microcapsule dosage increased. Moreover, elevating the healing temperature and extending the healing time were found to be effective strategies for enhancing the self-healing properties of microcapsule-modified asphalt. When the healing temperature matches the initial flow temperature, the healing index HI of 5% microcapsules modified asphalt approached nearly 100% within 5 min of healing time. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solution increased the electrostatic effect and interaction energy in asphalt binder and mastic. • The moisture damage on the asphalt-aggregate interface was the most obvious under alkaline erosion. • The moisture susceptibility of interface of mastic is lower than that of the binder. The asphalt mixture is easily affected by water erosion with different solutes. The molecular dynamics (MD) simulation method was adopted to explore the influence of solute on the nanostructure and interface interaction of both virgin/SBS asphalt binder and mastic. The changes of potential energy of asphalt solution erosion model (ASEM), as well as fractions aggregation caused by water molecules were observed. Moreover, differences on diffusion of water molecules caused by the studied solutes were explained. On this basis, the analysis of hydrogen bonds is also carried out. The results showed that saline/alkali solutes hindered the diffusion of water molecules, where water molecules in saline environment behaved the slowest diffusion rate. Meanwhile, salt maximized the hydrogen bond adsorption of water molecules on the surface of filler (silica). The mastic with a filler/binder ratio of 1.2 had the highest diffusion coefficient. From the interface perspective, an obvious interaction between calcite and solution was detected, and the salt and alkali proceeded the debonding effect of original water condition. The alkali solution led to the greatest moisture damage to the asphalt-solution-aggregate model (ASAM), followed by the saline solution. In this case, the SBS asphalt binder/mastic exhibited a higher water stability than the virgin. This study contributed to a basic reference for understanding the moisture-induced damage of asphalt mixtures under various solution conditions. [ABSTRACT FROM AUTHOR]

• Rheological properties of Basalt fiber and nano-TiO 2 /ZnO composite improve performances of asphalt binder. • Basalt fiber and nano-TiO 2 /ZnO composite can delay asphalt binder aging process. • The optimal content of nano-TiO 2 /ZnO is 4% in modified asphalt while content of basalt fiber is 6%. Nanomaterials and fibers have gradually become widely used modifiers in asphalt to improve the performance of pavements. However, studies have been focusing on the improvement of individual properties, while comprehensive analyses are still not available. In this study, different contents of nano-TiO 2 /ZnO and basalt fiber were used to prepare composite-modified asphalt binders. Using scanning electron microscopy (SEM), dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests, Fourier transform infrared (FTIR) spectroscopy, and other experimental methods, the rheological properties and microstructure of modified asphalt binders were determined. The tests results indicate that incorporation of nano-TiO 2 /ZnO and basalt fiber can significantly improve the high-temperature performance and fatigue life of composite-modifier asphalt binder before aging and after short-term, long-term, and ultraviolet (UV) aging. In addition, an improved permanent deformation resistance was obtained for asphalt pavement with basalt fiber and nano-TiO 2 /ZnO additives. However, low-temperature performance of asphalt binder was weakened by the addition of basalt fiber, while the appropriate amount of nano-TiO 2 /ZnO could eliminate negative effects. Moreover, the FTIR results suggest that there was no chemical reaction between basalt fiber, nano-TiO 2 /ZnO, and asphalt, and the modification mechanism is mainly of physical nature. Furthermore, the nanoparticles were more evenly distributed in the asphalt, which, together with the basalt-fiber-forming network structure hindered the propagation of internal microcracks. The conclusion of the tests is that the optimal content of nano-TiO 2 /ZnO is 4 wt% of the asphalt, while the content of basalt fiber is 6 wt%. [ABSTRACT FROM AUTHOR]

• Crystalline SA/PA-PCM enhanced the rutting resistance of the asphalt. • SA/PA-PCM formed a stable layered structure system inside the binder. • The maximum temperature difference between the asphalt was 11.5 °C. • The temperature peak of the modified binders lagged behind 40 min. To achieve the practical application of the stearic acid/palmitic acid binary eutectic phase change material (SA/PA-PCM) as an asphalt additive for cooling asphalt pavements in the summer, this study aimed to explore the direct interaction of asphalt with SA/PA-PCM. A series of tests were implemented to analyze the chemical composition, microstructure, thermophysical and rheological behaviors and thermal regulating properties of the SA/PA-PCM-modified binders. The results showed that a binder with a higher content of crystalline SA/PA-PCM corresponded to greater elastic modulus, complex modulus, elastic recovery potential, and creep behaviors, suggesting a positive role for SA/PA-PCM in the high-temperature rutting resistance and low-temperature cracking resistance of asphalt. These results are ascribable to the fact that incorporating SA/PA-PCM reconstructed the chemical composition of asphalt and formed a stable layered structure system inside the binder. However, the liquefied SA/PA-PCM destroyed the internal layered structure in the modified binders, resulting in a double loss of elasticity and viscosity. Furthermore, SA/PA-PCM improved the specific heat capacity of the binder by approximately 20%. The distinguished temperature regulating property was reflected by the obvious temperature difference (max 11.5 °C) and temperature hysteresis (approximately 40 min) between the modified binder and the base binder. [ABSTRACT FROM AUTHOR]

• Cereclor plasticizer improve aging resistance of the virgin asphalt binder. • Adding Cereclor has a good balance in remodeling the major fractions of asphalt binder. • The optimum Cereclor addition ratio to modified virgin asphalt was 6%. The study was explored the rheological performance of asphalt modified by esterified Cereclor plasticizer. 5-thioisophthalic acid (SDA) was used to graft the Cereclor in this laboratory investigation. The penetration, softening point, ductility, and viscosity of Cereclor-modified asphalt binder were all examined. Besides, the rheological behavior and chemical composition of asphalt modified by Cereclor was tested [e.g. dynamic shear rheometer (DSR), bending beam rheometer (BBR), gas chromatography-mass spectrometry (GC–MS), gel permeation chromatography (GPC), thin layer chromatography-flame ionization detection (TLC-FID), and fourier transform infrared (FTIR) tests]. The results showed that a Cereclor plasticizer can increase the viscous components and alleviate the stiffness of the virgin asphalt binder. The high content of light compounds in Cereclor balanced the chemical compounds of the virgin asphalt. Thus, the asphalt modified by Cereclor outperformed the virgin asphalt in terms of low-temperature cracking and fatigue resistance as well as anti-aging performance. However, FTIR results indicated that the aging properties of asphalt were not improved significantly by Cereclor with 8% concentration (by weight of virgin asphalt), due to the high proportion of the terminal chlorine atom, which is easily dehydrochlorinated. Moreover, when the Cereclor content was higher than 6%, Cereclor had less elevation on the anti-cracking capabilities of the modified asphalts. Therefore, Cereclor at a concentration of 6% was recommended for modifying the virgin asphalt binder to be used as a plasticizer in pavement construction. [ABSTRACT FROM AUTHOR]