It is of great benefit to the environment and the economy to use discarded tires pyrolysis carbon black (TPCB) nanoparticles as a modifier for asphalt binders. A base asphalt binder with 60/80 penetration (GF-70) was selected to prepare the TPCB-modified asphalt binder (TPCB/GF-70) with a 15% dosage of TPCB by the melt blending method. The test instruments, such as Fourier transform infrared spectroscopy, laser particle size analyzer, and thermogravimetric analyzer, were used to study the characteristics of TPCB. The physical performance of GF-70 and TPCB/GF-70 were tested and the rheological properties were also tested with a dynamic shear rheometer to investigate TPCB’s effect on the performance of GF-70. In addition, the aromatic hydrocarbon oil (AHO) was used as the softening agent for TPCB/GF-70. The pavement performance of AC-13 and AC-20 was studied to evaluate the comprehensive effect of TPCB and AHO on the pavement performance of asphalt mixtures. Results show that a 15% dosage of TPCB can significantly improve the anti-rutting performance of GF-70, and decrease the low-temperature performance of GF-70 within one PG grade. AHO can obviously improve the low-temperature performance of TPCB/GF-70, but does not significantly decrease the high-temperature performance. With the addition of AHO and a 0.1% higher oil aggregate ratio, TPCB tends to significantly improve the anti-rutting performance and the low-temperature performance of TPCB-modified mixtures; the moisture stability of TPCB and AHO composite modified mixtures satisfies the requirement of water stability.

A composite-modified asphalt was developed by incorporating tire pyrolytic carbon black (TPCB) with a silane coupling agent (SCA) to enhance its ductility and storage stability. The functional binding between asphalt and TPCB was improved by the addition of SCA. The gray correlation comprehensive evaluation method is incorporated into the response surface methodology (RSM), leading to an improved RSM. The improved RSM was employed to optimize the content of the modifier and the preparation process to enhance overall performance. A central composite design-based experiment was conducted to optimize the penetration, softening point, 10°C ductility, Brookfield rotational viscosity, and storage stability indicators of modified asphalt. The response surface of the gray comprehensive evaluation value of the evaluation indicators was calculated using the gray correlation analysis method, and a second-order regression model was established between independent variables such as TPCB, SCA content, and shear time factor and the gray comprehensive evaluation value. This model analyzed the impact of a single variable and variable interaction on the performance of the TPCB/SCA composite-modified asphalt. The optimized model results showed that the preparation parameters that optimize the expected comprehensive performance of the composite-modified asphalt are 9.2% TPCB content, 2.1% SCA content, and a shear time of 56.3 min. Finally, the TPCB/SCA composite-modified asphalt prepared with the improved RSM exhibited the highest gray comprehensive evaluation value and the best overall performance, indicating the feasibility of the optimized preparation parameters with the improved RSM.

This research focuses on the aging resistance properties of asphalt, which are crucial for determining the lifespan of asphalt pavement. To combat aging, waste tire pyrolysis oil (TPO) is often added to asphalt, enhancing its resistance to aging but compromising high-temperature performance. This study offered a pioneering solution by integrating TPO with polyphosphoric acid (PPA) to address these issues. In this study, we conducted a series of tests to characterize the properties of PPA/TPO modified asphalt, including temperature sweep and bending beam rheometer tests. The results demonstrated that the presence of PPA in the PPA/TPO modified asphalt could improve its high-temperature performance while maintaining its low-temperature properties. Moreover, PPA in the PPA/TPO modified asphalt enhanced the modified asphalt’s resistance to fatigue and deformation during the aging process, while the presence of TPO effectively reduced the impact of thermo-oxidative aging on the modified asphalt during the aging process. Additionally, physicochemical interactions between the base asphalt and modifiers were observed before and after aging. In summary, this study had offered an innovative method to enhance the anti-aging properties of asphalt, and had provided more options for sustainable, environmentally friendly roads.

To develop a novel self-healing asphalt binder and address the challenge of poor performance of waste tire pyrolysis oil-modified asphalt at high temperatures, this study employed polyphosphoric acid and waste tire pyrolysis oil for composite modification of asphalt. Subsequently, comprehensive evaluations of the modified asphalt were conducted using experimental techniques such as temperature sweep, time sweep, differential scanning calorimetry, Fourier-transform infrared spectroscopy, and fluorescence microscopy. The entropy weight method was utilized to determine the optimal dosage of modifiers in the asphalt binder and evaluate the comprehensive performance of the modified asphalt. Experimental results indicate that the introduction of polyphosphoric acid not only effectively maintains the self-healing properties of the modified asphalt but also significantly improves the negative impact of waste tire pyrolysis oil on the high-temperature performance of the asphalt binder. Analysis using the entropy weight method revealed that the optimal dosages of 2% polyphosphoric acid and 4% waste tire pyrolysis oil served as modifiers, resulting in the superior overall performance of the modified asphalt at these concentrations. In conclusion, the development of polyphosphoric acid/waste tire pyrolysis oil composite modifiers offer a novel avenue for the sustainable enhancement of asphalt modification.