Evolution of selective absorption for bitumen from Basic Oxygen Furnace Slag (BOF) during aging and rejuvenation in bituminous mixtures.

• Three layers of bituminous films at different stages of aging and rejuvenation were obtained by staged extraction method. • The selective absorption of bitumen by BOF is significantly higher than that by natural aggregate. The selective absorption of bitumen by aggregates exhibits a time-dependent effect. • The selective absorption of bitumen by aggregates is most significant during the short-term aging process. • Bitumen delamination occurs due to selective absorption of bitumen by aggregates, resulting in little effect on the road performance of bituminous mixtures. The selective absorption of bitumen by BOF has been systematically studied by previous scholars. However, there is still a lack of research on the selective absorption of bitumen by BOF at different aging stages. Hence, this issue deserves systematic investigation. Also in order to understand how to improve the pavement performance of BOF based bituminous pavement, this study is designed to explore the selective absorption behavior of BOF to bitumen components at different aging and rejuvenation stages. The protocols of short-term aging, PAV aging, and second PAV aging were subjected to specimens to simulate different service time of bituminous pavement. The complex modulus, phase angle, chemical composition and four component contents of different stages and layers of bituminous samples were analyzed by dynamic shear rheometer and Fourier infrared spectroscopy and thin layer chromatography with flame ionization detection. The road performance of the bituminous mixtures at different stages was also investigated. The results show that the BOF and natural aggregates all reveal selective absorption of bitumen, while BOF demonstrates a more significant effect for bitumen than natural aggregates. The selective absorption of bitumen by aggregates exhibits a time-dependent effect, resulting in the strongest selective absorption at the stage of short-term aging. Bitumen layers display multi layered system due to selective absorption of bitumen by aggregates, while effects insignificantly on the road performance of bituminous mixtures. The decrease in the ability of adhesion for bitumen due to aging is the key factor affecting performance of bituminous mixtures. [ABSTRACT FROM AUTHOR]