Rheological properties and modification mechanism analysis of coffee grounds modified asphalt.

Coffee grounds were thermally degraded to produce spent coffee grounds biochar (SBC), which was used for the bio-modification of asphalt. Rheological experiments and microscopic structure tests were conducted to investigate the effects of SBC on the high and low temperature rheological properties of asphalt and its modification mechanism. A 9% SBC content was selected to prepare asphalt mixtures, and their road performance was analyzed. The results showed that the irregular, rough, and porous structure of SBC could improve the high-temperature resistance to rutting and deformation of asphalt binder, and it was highly compatible with asphalt. The modification mechanism of SBC-modified asphalt was a physical filling effect rather than chemical modification. The road performance of asphalt mixtures showed that SBC could improve the resistance to water damage and high-temperature deformation of asphalt. Consistent with BBR rheological tests, SBC had a certain negative effect on the low-temperature performance of asphalt, but this effect was controllable. [ABSTRACT FROM AUTHOR]