Science of The Total Environment

Volume 804, 15 January 2022, 150194

Biochar for asphalt modification: A case of high-temperature properties improvement

Feng Ma^a Jiasheng Dai^a Zhen Fu^b Chen Li^a Yalu Wen^a Meng Jia^a Yujie Wang^a

KeShi^a

https://doi.org/10.1016/j.scitotenv.2021.150194Get rights and content
Link here

Highlights

•Biochar greatly increases the proportion of viscous components in the binder.
•Incorporating biochar into the binder improves high-temperature properties by approximately 35%.
•Biochar with fibrous porous structure forms a skeleton and hardening zone in the binder.
•Biochar modified binder is recommended to apply in subtropical and tropical regions.

Abstract

Biochar has been utilized as a renewable biomass resource to develop sustainable and eco-friendly pavements. This study focuses on the influence of biochar as an asphalt modifier on the improvement of high-temperature performance of asphalt. A series of tests were performed to comprehensively evaluate the high-temperature performance of the biochar modified binder. The interaction mechanism between the biochar and the binder was explored using scanning electron microscopy and Fourier-transform infrared spectroscopy (FTIR). The results indicated that the complex modulus and penetration of the biochar-modified asphalt binder could be increased by up to 35% and 36.5%, respectively, compared with those in case of the matrix asphalt, thereby improving the deformation resistance. In addition, the observed increase in the complex modulus, rutting factor, and viscosity–temperature index contributed to the improvement of temperature sensitivity and anti-rutting properties. These relationships are attributed to the fact that biochar has a fibrous porous structure and forms a skeleton and stiffening zone in the binder. Although biochar has a negative effect on the low-temperature properties of the binder, this can be alleviated by controlling the biochar content. Moreover, the FTIR results showed that no new chemical functional groups appeared after the incorporation of biochar into the binder. The internal chemical environment of the biochar-modified asphalt binder was different from that of the matrix asphalt. In conclusion, biochar is feasible as a modifier for binders owing to its high-temperature properties.

Graphical abstract