Assessing Rejuvenator Efficiency in Recycled Asphalt Using Gel Permeation Chromatography

The use of recycled materials in asphalt mixtures contributes to reducing costs and enhancing the longevity of road infrastructure. However, due to the presence of aged binder in reclaimed asphalt, additives known as rejuvenators are required to restore the lost properties of the binder. Researchers at Islamic Azad University (Tehran, Iran) evaluated the effects of various rejuvenators on the mechanical, rheological, and chemical properties of recycled asphalt mixtures to identify the most effective option for enhancing durability and performance. Various tests were conducted, including gel permeation chromatography (GPC), to assess the performance of different rejuvenators. A paper based on this research was published in Scientific Reports (1).

The authors write, “In recent years, greater attention to environmental issues and the depletion of natural resources has driven various industries toward using recycled materials and optimizing production processes. One key sector in this regard is road construction and asphalt production. Given the widespread need for construction and continuous road maintenance, recycled asphalt has emerged as a viable solution to reduce the consumption of natural resources and lower operational costs. Recycled asphalt is produced by reprocessing old asphalt mixtures and adding rejuvenators to restore their mechanical and functional properties.” (1)

Rejuvenators are defined as substances applied to restore the chemical and performance properties of asphalt mixtures. Rejuvenators are effective because they diminish the hardening effects and changes in aged asphalt’s chemical composition. These substances are primarily made up of maltenes, which play a significant role in influencing the properties of crude oils and derived products, and aromatic compounds, which replenish the maltenes lost from aged asphalt and restore much of the substance’s original characteristics. Aromatic compounds improve the rejuvenator’s compatibility with asphaltenes in bitumen, ensuring uniform distribution within the mixture (2-6).

Analysis indicated that rejuvenators with lower oxidation levels and specific compositions, such as WEG1, WCO, and WED1, demonstrated better performance in maintaining stiffness and preventing cracking. In addition, all the evaluated rejuvenator compositions exhibited satisfactory performance at high temperatures. Furthermore, findings revealed that different rejuvenators can have varying effects on the surface structure and material behavior. Results showed that the best performances are observed among the WEG3 and WED2 samples, with WEG3 exhibiting the best overall performance in improving the mechanical and rheological properties of recycled asphalt mixtures (1).

“This work advances the field by integrating molecular weight analysis and statistical validation, demonstrating that recycled materials like motor oil and cooking oil can perform as well or better than commercial rejuvenators. The findings emphasize the critical role of chemical composition and oxidation level in selecting optimal rejuvenators for recycled asphalt mixtures,” the authors wrote (1).

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References

1. Sabaei, M.; Hosseini, S. A.; Salami, B. et al. Performance Evaluation of Rejuvenators in Recycled Asphalt Mixtures Based on Mechanical and Rheological Properties. Sci. Rep. 2025, 15 (1), 39223. DOI: 10.1038/s41598-025-21557-7
2. Loise, V. et al. A Review on Bitumen Rejuvenation: Mechanisms, Materials, Methods and Perspectives, Appl. Sci. 2019, 9 (20), 4316. DOI: 10.3390/app9204316
3. Zaumanis, M.; Mallick, R. B.; Frank, R. Evaluation of Rejuvenator’s Effectiveness with Conventional Mix Testing for 100% Reclaimed Asphalt Pavement Mixtures. Transp. Res. Rec. 2013, 2370 (1), 17–25. DOI: 10.3141/2370-03
4. Im, S.; Zhou, F.; Lee, R. et al. Impacts of Rejuvenators on Performance and Engineering Properties of Asphalt Mixtures Containing Recycled Materials. Constr. Build. Mater. 2014, 53, 596–603. DOI: 10.1016/j.conbuildmat.2013.12.025
5. Shen, J.; Amirkhanian, S.; Tang, B. Effects of Rejuvenator on Performance-Based Properties of Rejuvenated Asphalt Binder and Mixtures. Constr. Build. Mater. 2007, 21 (5), 958–964. DOI: 10.1016/j.conbuildmat.2006.03.006
6. Maltenes. ScienceDirect website. https://www.sciencedirect.com/topics/engineering/maltenes (accessed 2025-11-11)