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In recent times both natural and synthetic rubber were blended with bitumen with the hope of producing a more durable hot mix asphalt. Although the application of natural rubber (NR) in bitumen modification have started long time ago prior to crumb rubber; only few literatures that completely characterised its performance are found today. This review aims to remind researchers and paving agencies on the benefits of NR rubberised asphalt. The study draw attention to NR production process and its unique properties, how NR was used to solve four major asphalt pavement failures namely rutting, fatigue, thermal cracking, and moisture susceptibility. It also presents barriers limiting the application of NR in bitumen modification with possible solution. Lastly, the concept of applying NR in warm mix asphalt was introduced.

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.

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High demand for asphalt binders in road construction verifies the need of finding alternative materials through asphalt pavement recycling. This paper investigated the impact of different rejuvenators on the performance of an aged asphalt binder. Virgin Olive oil, virgin cooking oil, waste cooking oil, virgin engine oil, and waste engine oil were added to a 30/40 penetration grade aged asphalt binder at a fixed oil content of 4% for all types. The wet method was used to blend the rejuvenators and aged asphalt binder. The physical, rheological, and chemical properties of the rejuvenated asphalt binder were evaluated using several laboratory tests which include penetration, softening point, bleeding, loss on heating, storage stability, penetration index, ductility, viscosity, dynamic shear rheometer, and Fourier transform infrared spectroscopy. The outcomes of the physical properties showed that the olive, waste, and virgin cooking rejuvenators can restore the aged asphalt binder to a penetration grade of 60/70. In contrast, the virgin and waste engine oil required a more quantity of oil to rejuvenate the aged asphalt binder. A sufficient amount of rejuvenator could regenerate the (G*/sin δ), (δ°), and (G*) for the aged asphalt binder. The addition of virgin olive and cooking oils in aged asphalt led to a rutting issue. No chemical reactions were observed with the addition of rejuvenators but they give an impact on reducing the oxidation level of the aged asphalt binder. As a result, further research should be performed on waste cooking oil given that it is inexpensive and provides excellent performance results. Doi: 10.28991/cej-2021-03091669 Full Text: PDF

In recent years, flexible pavement construction technology has relied heavily on the use of reclaimed asphalt pavement (RAP). However, the brittle nature of RAP, which stems from the use of an aged asphalt, has introduced numerous complexities into the process, with important implications to pavement service life. The properties of the aged asphalt can be rejuvenated to improve the performance and the behavior of RAP mixtures. This paper presents a review of past works that have used rejuvenating materials with RAP, including their benefits and drawbacks, as well as the optimal approach to increase RAP content in asphaltic mixtures. The method of rejuvenating aged asphalt and the mechanism of rejuvenation are also reviewed. The findings of this review can be used to predict the current and future challenges in the regeneration of RAP mixtures using rejuvenating materials.

Highlights• Hybrid rejuvenator with CR and WEO was used to restore the aged binder • Adding 100% RAP increased the stiffness and rutting resistance • Proper use of WEO-CR rejuvenator enhanced the performance