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To achieve efficient utilization of reclaimed asphalt pavement (RAP) materials, a bioregenerant (BR) was developed in this research, and waste vegetable oil (WVO), alkylphenol polyoxyethylene ether (APEO), plasticizer [tributyl acetylcitrate (ATBC)] and tackifying resin (FTR) were chosen as components of the regenerant. The composition ratio of BR was designed based on the response surface method (RSM), and the optimal BR dosage and the regeneration effect of BR on the bioregenerated mixture (BRM) with different RAP contents were determined and investigated. Results showed that the optimal composition ratio of BR was found to be WVO-APEO-ATBC-FTR=100:2:23:10. The addition of BR significantly reduced the high-temperature stability and aging resistance of the mixture, but improved its low-temperature cracking resistance and fatigue resistance. Additionally, BR prominently contributed to the improvement for the water stability of the regenerated mixture, and its regeneration effect was found to be similar to that of two commercial regenerants, although excessive BR led to the decline of water stability. Moreover, the high-temperature stability and aging resistance of BRM when mixed with 20%, 30%, and 40% RAP were similar to those of the new asphalt mixture (NAM). At 20%, 30%, and 40% RAP content, both the low-temperature cracking resistance and fatigue resistance of BRM met the requirements. However, when the RAP content exceeded 40%, the water stability of BRM went beyond the specification limit. Taking into account the overall road performance, it is suggested that the optimal BR dosage is 5%–9%, and the maximum RAP content ensuring the road performance of BRM meets the requirements is 40%. These research findings will contribute to addressing the stacking problem of reclaimed asphalt pavement materials and environmental pollution, aligning with green and environmentally friendly sustainable development principles. [ABSTRACT FROM AUTHOR]

The research aims to illuminate the interfacial fusion mechanism of rejuvenator-aged asphalt to guide the development of high-performance rejuvenators and foster the high-value utilization of waste asphalt pavement materials. In the research, the contact angle between rejuvenator and aged asphalt was measured to assess its interface wettability, and the permeability and contributing factors in aged asphalt were profiled based on the permeation test and permeation degree parameter. Concurrently, the molecular dynamics simulations of the fusion behavior between rejuvenator and aged asphalt were conducted to comprehend the fusion mechanism deeply. Results reveal that thermal oxygen and photo-oxygen aging enhanced the asphalt mixture's hydrophobicity with similar effects, and they also had comparable impacts on the wettability of rejuvenator-aged asphalt interface. A more considerable asphalt aging eventuated a more challenging for the rejuvenator to wet the asphalt surface naturally. Waste vegetable oil rejuvenators tended to have a superior wetting effect on the aged asphalt surface compared to mineral oil rejuvenators. Higher permeation temperatures and permeation durations facilitated the rejuvenator's fusion with aged asphalt, and the permeability varied across different rejuvenators, hinging on the rejuvenator's permeation performance and composition. The rejuvenator's permeation process into light aged asphalt or aged matrix asphalt was prone to occur. The aging effect of asphalt negatively impacted the fusion process of the layered system. Compared to oleic acid, aromatic hydrocarbons exhibited superior permeation ability and better fusion effect with aged asphalt. Rejuvenator composition materials yielding high permeation and fusion effects should display the following characteristics: lower viscosity, weak molecular polarity, small molecular weight, linear molecular structure, or end phenyl ring structure. • Aging eventuated a more challenging for rejuvenator to wet the asphalt surface. • The wetting effect of waste vegetable oil rejuvenators was superior to that of mineral oil rejuvenators. • The rejuvenator's permeation process into light aged asphalt or aged matrix asphalt was prone to occur. • Compared to oleic acid, aromatic hydrocarbons exhibited superior fusion effect with aged asphalt. [ABSTRACT FROM AUTHOR]

In order to develop an environment-friendly asphalt rejuvenator, waste vegetable oil (WVO) was selected as the base oil. The composition of the rejuvenator was first designed based on the response surface methodology (RSM), and 16 groups of rejuvenator samples were obtained. Then, these samples were used to regenerate aged asphalt and 16 groups of rejuvenated asphalt samples were prepared. Afterward, the viscous, conventional, rheological, and fatigue resistance properties of these rejuvenated asphalts were measured and evaluated, and the optimal composition of rejuvenator was determined. Results show that the addition of WVO-based rejuvenator can reduce the viscosity and softening point of aged asphalt, increase its penetration and ductility, and restore the physical properties and viscosity of aged asphalt to that of original asphalt. With the addition of WVO-based rejuvenator, the high-temperature performance of aged asphalt gradually declined, but the rejuvenator with optimal composition can restore its high-temperature performance to the similar level as original asphalt. The addition of WVO-based rejuvenator can evidently improve the fatigue damage resistance and low-temperature cracking resistance of aged asphalt, achieving a good regeneration effect. The fitting equation based on RSM can achieve an accurate and reliable prediction on the viscous, conventional, rheological, and fatigue damage properties of rejuvenated asphalt. According to the results of model optimization, the optimal composition of WVO-based rejuvenator is recommended as WVO:Dibutyl phthalate (DBP):antiaging agent (AA) = 90:9:1. [ABSTRACT FROM AUTHOR]

To explore the macroproperties of biorecycled asphalt and the correlation between its components and macroproperties, the cooking-aged waste soybean oil was used as the base oil, along with mixing additives, to prepare the biorejuvenator, and a total of six biorejuvenators with different component ratios were first developed. Then, using these rejuvenators, six biorecycled asphalts were prepared and their chemical components and viscosity and a series of pavement properties were measured and evaluated. Finally, using the gray correlation theory, gray correlation analysis between macroproperties and four components was conducted for recycled asphalts. Results show that the addition of biorejuvenator can adjust the component distribution in the aged asphalt, and the components in the aged asphalt can be gradually restored to the original level, thus achieving the regeneration of aged asphalt. Biorejuvenator can restore the penetration, softening point, ductility, and viscosity of aged asphalt to the same level as original asphalt. Further, the biorejuvenator with appropriate composition can restore the rheological parameters such as G* , δ , Jnr , Nf , S , and m of aged asphalt to the level consistent with that of original asphalt. And it can significantly improve the low-temperature and fatigue properties of aged asphalt, while ensuring that the high-temperature performance of regenerated asphalt meets the specification requirements. Overall, the regeneration effects of R5 [base oil: dibutyl phthalate (DBP): antiaging agent: stabilizer=88∶10∶1∶1 ] and R6 (base oil: DBP: antiaging agent: stabilizer=90∶8∶1∶1) are optimal, which can guarantee that the pavement performance of recycled asphalt basically meets the requirements of original asphalt. The gray correlation analysis shows that the change of the four components of biorecycled asphalt will significantly affect its viscosity, high- and low-temperature performance, and fatigue behavior. The seven indexes of δ , softening point, penetration, m , viscosity, S , and Nf2.5 demonstrate a higher gray correlation with the four components of asphalt (all exceed 0.6), followed by ductility, Jnr0.1 , and Jnr3.2. However, G* correlates poorly with the four components of asphalt, whose gray correlation degree is not more than 0.4. [ABSTRACT FROM AUTHOR]

• Bio-rejuvenators include wood fiber, animal manure and waste oil types. • Bio-rejuvenator improves cracking resistance and moisture resistance. • Bio-rejuvenator reduces high temperature performance of aged asphalt. • Bio-rejuvenator restores the composition and performance of aged asphalt. To make full use of massive waste asphalt materials produced in the road construction and maintenance, and to solve the problems of low efficiency and poor environmental protection of petroleum-based rejuvenators, bio-rejuvenator was proposed to regenerate the waste asphalt materials. The bio-rejuvenator is a green, environmental protection and renewable material, which has a very wide application prospect in the regeneration. For the purpose of promoting the later research and application of bio-rejuvenator, this review summarizes the research progress of bio- rejuvenator in the regeneration of waste asphalt materials. The review results show that the bio-rejuvenator can significantly improve the low-temperature performance of waste asphalt binder, and restore its high-temperature performance to the level consistent with the virgin asphalt. Moreover, the bio-rejuvenator of waste oil type is studied most at present, and its optimum dosage is kept within about 18%, followed by wood fiber type, with a recommended optimum dosage of 5% ~ 20%. There are relatively few studies regarding animal manure type-rejuvenator, and the optimal dosage of swine manure-based bio-rejuvenator is approximately 5% ~ 10%. The addition of bio-rejuvenators can restore the chemical composition and pavement performance of aged asphalt, and achieve its regeneration. Among them, these four bio-rejuvenators of waste soybean oil (WSO), tung oil (TO), waste vegetable oil (WVO) and waste cooking oil (WCO) can significantly decrease the functional group index of aged asphalt, and WCO and 9% waste pig fat (WPF) can restore the four component content distribution of aged asphalt to the same level as virgin asphalt. Furthermore, the bio-rejuvenated asphalt mixture possesses good low-temperature crack resistance, moisture resistance and fatigue crack resistance; moreover, an appropriate amount of bio-rejuvenator can restore the high-temperature stability of the old asphalt mixture to the same level as that of fresh asphalt mixture. Future researches should be executed from the following aspects: further explore how to raise the utilization rate of waste asphalt material meanwhile guaranteeing the sufficient performance of bio-rejuvenated mixture; further explore the regeneration mechanism of bio-rejuvenator on aged asphalt from the micro- even nano-scale as well as the regeneration effect of bio-rejuvenators from other biomass sources; investigate its application in warm-mixed rejuvenated asphalt mixture while focusing on the regeneration of hot-mixed asphalt mixture by bio-rejuvenator; further research regarding fatigue property of rejuvenated asphalt mixture should be conducted and fatigue life prediction model should be also investigated; forming a unifying technical specification for bio-regeneration technology to standardize its application in the regeneration of waste asphalt materials. [ABSTRACT FROM AUTHOR]