Thermal Storage Stability of Bio-Oil Modified Asphalt

This study investigates and evaluates the storage stability of asphalt binder modified by bio-oil at high temperature. Five bio-asphalts are prepared by adding 10, 15, 20, 25, and 30% bio-oil into 70# petroleum asphalt. The bioasphalts are statically stored for 48 h at four different temperatures: 120, 140, 160, and 180°C. The softening point test, rotational viscosity test, dynamic shear rheometer (DSR) test, and Fourier transform infrared spectroscopy (FTIR) test are applied. The top and bottom sections of samples after thermal storage are analyzed for thermal storage stability from three aspects: physical properties, rheological properties, and functional group composition. The results show that after thermal storage, the bioasphalts segregated and the softening point, viscosity, and antirutting factor of the bottom sections are larger than those of the top sections. The viscosities of the top and bottom sections of bioasphalt with 20% bio-oil are 0.507 and 0.643 Pa·s, respectively, under the storage temperature of 140°C. Moreover, the thermal storage stability of bioasphalts decreases with an increase in bio-oil content and storage temperature. Furthermore, based on rheological properties and functional group analysis, it is found that physical segregation and chemical reactions occurred, such as carbonation reactions, reactions between the oligomers, and volatilization of aromatic compounds. Overall, it is recommended that the storage temperature should be kept below 160°C and the bio-oil content should be less than 25%.