Revelation and characterization of selective absorption behavior of bitumen to basic oxygen furnace slag

Abstract Previous studies have indicated that not all bituminous components are assimilated into the porous structure of the aggregates. However, the absorption of bitumen to basic oxygen furnace (BOF) slag with outburst pore characteristic is still not clear. To further understand the service characteristics and improve the application quality of BOF slag, the absorption behavior of bituminous components to BOF slag was explored in this paper. Dynamic shear rheological (DSR) and contact angle measurement instrument were firstly applied to evaluate complex modulus and surface energy of bituminous components. The morphology and pore characteristics of Sg and Sh slags were investigated by SEM and X-ray computed tomography (CT). Then ultraviolet analyzer was conducted to observe fluorescence distribution of BOF slags soaked in bitumen-toluene for revelation of selective absorption behavior. Subsequently, the distribution law of bituminous components in the pore of the BOF slag were characterized by nanoindentation instrument. The results show that connected pores existing in BOF slag have remarkable absorption effect on bitumen through CT image acquisition. The fluorescence effect only appearing on the surface of BOF slag soaked for 90d has verified selective absorption behavior of bitumen. Bituminous components with larger modulus and lower surface energy tend to distribute at the outer layer of BOF slag pores, while lightweight components like saturates and aromatics are inclined to deposit at the inter layer. The modulus interval of bitumen area on the surface of Sh slag is smaller than that of Sg slag, which is ascribed to that Sh slag provided with abundant pore structures and smaller pore diameter ranging from 1 to 15 μm can selectively absorb more light components.