Biochars from Cotton Seed, Camelia Seed Shell, and Coffee Ground in Modification of Asphalt: Fundamental Properties, Rheological Performance, and Inhibition of VOC Emissions

With the increasing requirement for asphalt modification, a new environmentally friendly asphalt modifier is needed. In this study, three varieties of biomass, cotton seed (CO), camelia seed shell (CA), and coffee ground (CG), were chosen for biochar preparation and asphalt modification to find an environmentally friendly asphalt modifier. A segregation test was applied to evaluate the storage stability of the modified asphalt. A dynamic shear rheometer (DSR) temperature sweep and frequency sweep were used to characterize the high-temperature performance. The low-temperature performance was evaluated by the bending beam rheometer (BBR) test. The DSR results indicate that the rutting factor increase for modified asphalt at high temperatures is CO ≈ CG > CA, and a high temperature could reflect the biochar's properties better in modified asphalt. Furthermore, the low-temperature deterioration is well controlled in CO and CA biochar-modified asphalt. Finally, the volatile organic compound (VOC) emission behavior was evaluated using gas chromatography-mass spectrometry (GC-MS).