Effect of Biochar from Oat Hulls on the Physical Properties of Asphalt Binder

Abstract

The purpose of this study was to verify the feasibility of using biochar from oat hulls (BO) as a potential bio-modifier to improve the physical properties of conventional asphalt binder. The BO and asphalt binder were characterized by confocal (fluorescence) laser microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. Then, an asphalt binder modification procedure was established and modifications with 2.5, 5.0 and 7.5% of BO on the weight of the asphalt binder were evaluated, using a particle size < 75 µm. The physical properties of the evaluated modified asphalt binder with BO were: rotational viscosity in original and aged state, aging index, Fraass breaking point, softening point, penetration, penetration rate and storage stability. The results indicated that the BO has a porous structure, able to interact with the asphalt binder by C=O and C=C bonds. In addition, modification of the asphalt binder with BO increases the rotational viscosity related to high-temperature rutting resistance. The results obtained from the Fraass breaking point and softening point indicated that the use of BO extends the viscoelastic range of the asphalt binder. In addition, the evaluated modifications present low susceptibility to aging and good storage stability.