Reclaimed asphalt pavement (RAP) has received much attention recently due to its increased use in hot mix asphalt (HMA) pavements to enhance pavement sustainability. The use of aged asphalt in RAP, which is highly oxidised and has lost its properties due to exposure to traffic loads and climatic conditions throughout its lifespan, can cause asphalt mixtures to stiffen and embrittle, thus negatively affecting the behaviour of asphalt mixtures. This issue may be resolved by including rejuvenating agents that can restore both physical and rheological properties of aged asphalt by increasing maltene fractions and decreasing asphaltene. However, the high restoration capacity of any kind of rejuvenating agent does not assure the durability of restored aged asphalt. This study explored the performance and durability of rejuvenated asphalt mixtures embedded with several types of rejuvenators identified from the extensive literature review. The study serves as a significant reference to predict future challenges in rejuvenating aged asphalt.

The properties of aged asphalt can be renewed using rejuvenating agents. Rejuvenators can improve the performance of reclaimed asphalt pavement (RAP) by reducing the asphaltene-to-maltene ratio back to their initial state. This study assessed the function of maltene as a rejuvenator to renew aged asphalt. Penetration, softening point, ductility and viscosity tests were performed to determine the ideal maltene content to be incorporated into RAP. The rejuvenated asphalt samples were evaluated using rolling thin film oven (RTFO), dynamic shear rheometer (DSR), bending beam rheometer (BBR), Fourier transform infrared (FTIR), thermogravimetric (TGA) and atomic force microscopy (AFM) measurements. The outcomes were compared with virgin and aged asphalts. Both oxygenated groups and asphaltene content decreased by adding 12% maltene. Essentially, DSR, BBR, TGA, and AFM analyses divulged the comparable performance of rejuvenated asphalt with virgin asphalt, signifying the potency of maltene for practical applications.

Rejuvenating agents are considered desirable options in rejuvenating recycled asphalt’s properties. Hence, the capability of integrating waste engine oil (WEO) and maltene to rejuvenate the traits of recycled asphalt was investigated. The penetration, softening point, ductility and viscosity were measured to determine an ideal amount of hybrid rejuvenating agent. Then, the rejuvenated asphalt was evaluated against different samples through maltene to asphaltene ratio, rolling thin film oven (RTFO), storage stability, dynamic shear rheometer (DSR) and bend beam rheometer (BBR) tests. Later, the Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and contact angle were employed. Based on the physical tests and the statistical analysis, the properties of recycled samples were restored approximately to that of the virgin asphalt by adding appropriate doses of hybrid rejuvenating agent. Meanwhile, the DSR and BBR results reported comparable performance between the rejuvenated and virgin samples. The hybrid rejuvenating agent has reduced the chemical ageing index and asphaltene content of the recycled asphalt. Moreover, TGA exhibited that the rejuvenated samples became more sensitive to temperature compared to recycled asphalt. In conclusion, 5% and 10% of the hybrid rejuvenating agent can renovate recycled asphalt for subsequent reuse in pavements depending on the characteristics of recycled asphalt.

Asphalt hardens as a result of an aging process. This study was undertaken to determine the effect of field aging simulated by laboratory aging method of different hot mix asphalt (HMA) mixture. Three types HMA mixtures were used for this study namely Asphaltic Concrete with 10 mm nominal maximum aggregate size (AC 10), Aspaltic Concrete 28 mm (AC 28) and Porous Asphalt 10 mm (PA 10). The resilient modulus test was carried out as an indicator of the performance at a 25 °C and 40 °C. Generally, all samples show similar trend which aged mixture produced slightly higher resilient modulus compared to unaged mixture while an increase in temperature from 25 °C to 40 °C might reduced the resilient modulus up to 88%. This study also found that the difference increment of resilient modulus after the aging process attributed by asphalt content, air void and gradation of respective mixtures.

Bitumen pavements play a critical role in modern transportation infrastructure, providing durable and reliable surfaces for roads and highways. However, traditional bitumen modifiers often rely on non-renewable resources and may contribute to environmental degradation. In response to the need for sustainable alternatives, this study explores the potential of utilizing sawdust (SD) and charcoal ash (CA) as bitumen modifiers. SD and CA were blended with bitumen grade 60/70 with 0% (control) and varied amounts of proportion using combination of SD and CA. Moreover, the sustainable modified bitumen mixture was assessed using the Marshall stability, indirect tensile strength and loss abrasion test. Specifically, adding 7SD0.5CA performs the best in stability as a sustainable modified bitumen mixture. The correlation between stability, tensile strength and loss abrasion for SD and CA modified bitumen mixture was significant, with a strong Coefficient of Determination (R2) of average 0.96 for all testing parameters. According to this study’s findings, the correlation of SD and CA content may improve the performance and engineering characteristics with respect to sustainable modified bitumen.