Desulfurized rubber (DR) and low-density polyethylene (LDPE) were used to modify bitumen. The basic physical properties, rheological properties, chemical composition, thermogravimetric behavior, and morphological characteristics were determined and evaluated to analyze the performance and mechanism of DR and LDPE compound-modified asphalt. A series of experiments (e.g., conventional test methods, rotational viscosity, storage stability, and dynamic shear rheometer tests), Fourier transform infrared spectroscopy, thermogravimetric analysis-differential scanning calorimetry, fluorescence microscopy, and atomic force microscopy were conducted. The results revealed that DR-modified asphalt (DRMA) had increases in the penetration, ductility, softening point, and penetration index by 30.2, 22.3, 3.5, and 11.1%, respectively, over the crumb rubber-modified asphalt (CRMA). The compatibility between the asphalt and modifier is better for DRMA than for CRMA. These findings indicate that DRMA has a better pavement performance than CRMA. Furthermore, compared with DR-modified bitumen, LDPE inclusions increased the value of G*/sin δ by at least 75.9% and improved the thermal properties. Morphological observations confirmed that the DR/LDPE additives were better dispersed than crumb rubber and formed a more homogeneous phase separation in the asphalt.

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The objective of this research is to investigate the physiochemical and rheological properties of waste cooking oil (WCO)/styrene‐b‐butadiene‐b‐styrene/ethylene vinyl acetate (SBS/EVA) composite modified asphalt. A petroleum asphalt composite modified with SBS/EVA and oil/SBS/EVA were prepared to undergo the physical, rheological, and microscopic experiments. Comparing these tests results with the properties of unmodified petroleum asphalt, SBS and EVA cause an improvement in pavement performance, but weaken the storage stability. Although the high‐temperature performance undermined by the addition of WCO, the thermal stability, fatigue property, and low temperature crack resistance improved obviously. In addition, WCO mainly composed by low‐weight components, and these can supplement the light components in the polymer‐modified asphalt. EVA could increase the percentage of large molecular size of asphalt, while WCO relieves this trend. The reactions between WCO and these polymers (SBS and EVA) are physical reactions. Atomic force microscopy morphology results reflect that SBS and EVA increase the surface complexity and roughness, and WCO makes the asphalt surface smooth. This indicates WCO increases the dispersion of polymers in asphalt. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48828.

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The aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel‐permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti‐cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high‐average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.