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The purpose of this research is to solve the problem of debonding of polyacrylonitrile (PAN) fibers in asphalt to improve the property of asphalt materials. A simple layer-by-layer self-assembly method was employed, in which a chitosan (CS)/phytanic acid (PA) coating was first constructed on the fiber surface. This coating immobilized Fe3O4 nanoparticles on the fiber surface by electrostatic adsorption and coordination, resulting in a robust active surface to obtain Fe3O4-PA-CS-PAN fibers, which were used to laminate styrene–butadiene–styrene (SBS)-modified asphalt. Dynamic shear rheometer (DSR) tests confirmed that the Fe3O4-PA-CS-PAN fiber-modified asphalt possessed superior viscoelastic properties and rutting resistance. At 64 °C, the viscosity modulus (G′) and viscous modulus (G′′) of the 1.5% Fe3O4-PA-CS-PAN fiber-modified asphalt increased by 18.23% and 26.19%, respectively, compared with that of the same dosage of PAN fiber-modified asphalt. This can be ascribed to the effective enhancement of the bonding of the interface between the modified PAN fibers and the asphalt. This research contributes to the development and improvement of future road materials. [ABSTRACT FROM AUTHOR]

To optimize the rheological properties of warm-mix asphalt and analyze its ultraviolet (UV) aging behaviors, organic montmorillonite was selected to modify the Sasobit warm-mix asphalt. 3% Sasobit was added into the hot mix asphalt to prepare warm-mix asphalt; and then, three different contents of organic montmorillonite (1%, 2%, and 3%) were added to modify the warm-mix asphalt compositely. Subsequently, the road performance and UV aging behaviors of prepared asphalt were evaluated by some rheological indicators; and then, the modification mechanism was investigated by micro testing methods, including Fourier transform infrared spectroscopy (FTIR) test and Fluorescent microscope (FM) test. Results show that with the introduction of Sasobit, construction workability and high-temperature properties of hot mix asphalt were improved, while its fatigue performance and low-temperature properties were decreased. Fortunately, adding organic montmorillonite into the prepared warm-mix asphalt can significantly optimize its fatigue performance while having little influence on its low-temperature properties. UV aging test results show that DSRFn is the most sensitive indicator to characterize the UV aging behaviors of asphalt. Meanwhile, DSRFn aging indexes of warm-mix asphalt and those with 1%–3% organic montmorillonite were reduced by 28.88%, 46.41%, 48.55%, and 46.15%, respectively, compared with that of hot mix asphalt, indicating that Sasobit warm-mix asphalt has superior aging resistance than hot mix asphalt and that the addition of organic montmorillonite can further improve this ability. Microscope test results confirm that the intercalated structure or exfoliated structure may be formed in the asphalt binders, thereby enhancing the rheological properties. In accordance with the presented results, it is recommended that the optimum content of montmorillonite is 2%, which can promote the prepared asphalt samples to obtain excellent rheological properties. [ABSTRACT FROM AUTHOR]

To improve the performance of desulfurized rubber modified asphalt (DRMA), especially its high‐temperature performance, three modifiers (including polyphosphoric acid [PPA], styrene‐butadiene‐styrene [SBS], and rock asphalt) were selected to modify DRMA respectively. The conventional performance, rheological properties, chemical composition, and thermal decomposition were characterized to analyze the performance and modification mechanism of DRMA and its composites. Test results show that, the addition of PPA, SBS, and rock asphalt can all improve the high temperature of DRMA, among which the desulfurized rubber/rock asphalt compound modified asphalt (DRMA‐ROCK) has the best high‐temperature performance; however, its construction workability, storage stability, and low‐temperature performance are poor. In contrast, desulfurized rubber/PPA compound modified asphalt (DRMA‐PPA) not only has better high‐temperature performance, but also has excellent low‐temperature performance, storage stability, and fatigue performance. Fourier infrared spectroscopy (FTIR) test confirms that the modification process of DRMA by these modifiers is chemical modification, and the characteristic peak indexes obtained from FTIR also prove that DRMA‐ROCK has better high‐temperature performance but poor construction workability from the microscopic point of view. Furthermore, thermogravimetric analysis‐differential scanning calorimetry test shows that the addition of rock asphalt improves the thermal stability of DRMA, while PPA and SBS decrease its thermal stability. From the above results, it can be concluded that DRMA‐PPA has excellent comprehensive properties. [ABSTRACT FROM AUTHOR]

• Analyze the UV aging characteristics of asphalt binders from multiple scales. • Explore the effects of UV aging on rheological properties of asphalt binders based on some rheological models. • Propose some suitable evaluation indexes to quantitatively characterize the UV aging degree of asphalt binders. • Discuss the relationships among the macro properties and micro properties of asphalt binders before and after UV aging. Aiming to propose some suitable evaluation indexes to quantitatively characterize the UV aging resistance of asphalt binders, firstly, effects of UV aging on asphalt's properties were comprehensively explored from the multiple scales, including their physical rheological properties, chemical compositions and microscope morphology. The above properties of asphalt binders before and after UV aging were respectively measured with the conventional physical properties tests, dynamic shear rheometer (DSR) test, thin-layer chromatography test (TLC) test, gel permeation chromatography (GPC) test and atomic force microscopy (AFM) test. Subsequently, based on some principles for establishing evaluation indexes, such as discrimination, regularity and consistency, the optimal evaluation indexes were proposed to quantitatively characterize the UV aging resistance of asphalt binders. Finally, relationships between the physical properties, chemical compositions and micro morphology of asphalt binders were discussed with the Pearson correlation coefficient method. Test results show that UV aging has a significant effect on physical rheological properties of asphalt, and ranking of aging resistances among asphalt binders evaluated by different macro indices are nearly consistent. Among these macro indexes, the G-R parameter aging index are proved to be the evaluation index with the highest discrimination degree, followed by complex shear modulus G* aging index (60 °C, 10 rad/s, 1 %) and zero shearing viscosity ZSV aging index (60 °C). Chemical composition test results demonstrate that with the growth of UV aging degree, resins components in asphalt increase gradually, while aromatics components decrease, which results in the proportion of larger molecular size (LMS) in asphalt gradually increases. And AFM test results show that UV aging will cause the number of the "bee structure" and roughness values of asphalt gradually decrease, thus promoting the transformation of the asphalt micro structure to smooth. Pearson correlation analysis indicates the compared with the roughness R a , the Gel index I c and LMS possesses higher correlation with G-R and G* , whose R values both exceed 0.8. Thus, it may be appropriate to adopt some chemical composition evaluation indexes (such as I c , LMS) to characterize the UV aging degree of asphalt binders from the microscope perspective. [ABSTRACT FROM AUTHOR]

To promote the application of warm mix asphalt (WMA) technology in strong UV areas, warm mix SBS modified asphalt binders with better UV aging resistance were developed in this study. The conventional physical properties, viscosity-temperature characteristics, rheological properties and storage stability were carried out to analyze the performance of the prepared modified asphalt containing Sasobit and OMMT. Then, TOPSIS method was selected for multi-index optimization to optimize the dosage of OMMT and Sasobit. Subsequently, the warm mix effect, high temperature property and aging resistance of the developed modified asphalt were further evaluated. Finally, the modification mechanism was characterized with FTIR, XRD and FM. Test results show that, Sasobit can significantly improve the construction workability of asphalt, and OMMT can enhance the storage stability and UV-aging resistance. In addition, the two modifiers can both improve the high temperature property of SBS modified asphalt. Based on the multi-index optimization results, it is recommended that the optimal dosage of Sasobit and OMMT is 3% and 2%, respectively. And microstructure characterization test results reveal that the asphalt chains and polymer molecules have been successfully intercalated into the layers of OMMT molecules, and further the exfoliated structure has been formed in the composite asphalt blend, thus improving its road performance. From the above results, it can be concluded that both additives play their own advantages at their optimum dosages. • Warm mix asphalt with better aging resistance was developed. • Optimum dosages of modifiers were obtained based on multi-index optimization. • The modification mechanism of asphalt was evaluated by FTIR, XRD and FM. • Exfoliated structure has been formed in the composite asphalt blend. [ABSTRACT FROM AUTHOR]

• PRM, XT-2 and XT-3 can all improve the rheological properties of base asphalt. • HMAC should meet the requirements: G* (60 °C, 10 Hz, 0.1%) ≥ 60.0 kPa. • HMAC should meet the requirements: G*/sin δ (76 °C, 5 Hz, 0.1%) ≥ 5.0 kPa. • J nr.3.2 (76 °C) ≤ 2.0 kPa−1 can be used as a reference index to define HMAC. In order to study the high temperature rheological properties of high modulus asphalt cement (HMAC) and clarify its definition criteria, firstly, three kinds of HMAC binders were prepared with high modulus modifiers and subjected to dynamic shear rheological test (DSR), zero shear viscosity test (ZSV) and multi-stress creep recovery test (MSCR). Based on the tests and analysis, the complex shear modulus (G*), rutting factor (G*/sin δ), zero shear viscosity (ZSV) and unrecoverable creep compliance (J nr) were taken as technical indexes for the performance evaluation of HMAC. Further, through analyzing the consistency of evaluation results of different evaluation indicators and the correlation between evaluation indicators of HMAC binders and HMAC mixtures, the definition criteria of HMAC binder are eventually given. The test results show that the three high modulus modifiers can improve the viscoelastic properties and high temperature properties of the matrix asphalt, but the modification effect is slightly different; the rheological properties index can basically make a consistent evaluation of the high temperature performance of three kinds of HMAC binders, but the correlation degree is different. The dynamic stability (DS) of the mixture is well correlated with G* (60 °C, 10 Hz, 0.1%) (refers to the complex shear modulus measured at 60 °C, loading frequency 10 Hz and strain level 0.1%), G*/sin δ (76 °C, 5 Hz, 0.1%) (refers to the rutting factor measured at 76 °C, loading frequency 5 Hz and strain level 0.1%), zero shear viscosity (60 °C) and J nr. 3.2 (76 °C) (refers to the unrecoverable creep compliance measured at the stress level of 3.2kpa and the temperature of 76 °C), but the correlation of dynamic modulus (E*) with zero shear viscosity (60 °C) and J nr. 3.2 (76 °C) is poor. In summary, it is recommended that HMAC binder should meet both G*(60 °C, 10 Hz, 0.1%) ≥ 60.0 kPa and G*/sin δ (76 °C, 5 Hz, 0.1%) ≥ 5.0 kPa, and the definition criteria can be as a design basis for HMAC binder. At the same time, it is recommended to use J nr.3.2 (76 °C) to evaluate the high temperature performance of HMAC. [ABSTRACT FROM AUTHOR]