Abstract
To improve the performance of petroleum asphalt, bio-char was used as a modifier for a petroleum asphalt binder, in this study. The rheological properties of bio-char modified asphalt binders were compared with different particle sizes and contents, with one control and one flake graphite modified asphalt binder. Specifically, the bio-char modifiers with two particle sizes (ranging from 75 μm–150 μm and less than 75 μm) and three contents of 2%, 4%, and 8% were added into the asphalt binder. A flake graphite powder with particle sizes less than 75 μm was used as a comparison modifier. The Scanning Electron Microscopy (SEM) image showed the porous structure and rough surface of bio-char as well as dense structure and smooth surface of flake graphite. A Rotational Viscosity (RV) test, Dynamic Shear Rheometer (DSR) test, aging test, and Bending Beam Rheometer (BBR) test were performed to evaluate the properties of bio-char modified asphalt in this study. Both modifiers could improve the rotational viscosities of the asphalt binders. The porous structure and rough surface of bio-char lead to larger adhesion interaction in asphalt binder than the smooth flake graphite. As a result, the bio-char modified asphalts had better high-temperature rutting resistance and anti-aging properties than the graphite modified asphalt, especially for the binders with the smaller-sized and higher content of bio-char particles. Furthermore, the asphalt binder modified by the bio-char with sizes less than 75 μm and about 4% content could also achieve a better low-temperature crack resistance, in comparison to other modified asphalt binders. Thus, this type of bio-char particles is recommended as a favorable modifier for asphalt binder.
Highlights
Bio-char has been studied since the 20th century [1]
The rheological properties were evaluated in the laboratory, and the effect of microscopic morphology, the particle size and the content of bio-char in the properties of bio-char modified asphalt binder, were researched in this study
The Dynamic Shear Rheometer (DSR) test can be conducted to determine the rheological behavior of asphalt binders in varying temperature and frequency conditions [40,41]
Summary
Bio-char has been studied since the 20th century [1] It is a product rich in carbon consisting of organic compounds, generally produced by pyrolysis technology [2,3]. It is likely that bio-char can be used as a modifier for asphalt modification, to reduce environmental impacts and human health concerns. With the addition of carbon fiber, the high-temperature properties and rutting resistance of asphalt binder, as well as the alleviation of the aging and oxidation processes, were improved [26,27]. A limited number of studies have focused on the performance evaluation of modified asphalt by using bio-char from waste wood as a modifier. The rheological properties of asphalt binder modified by bio-char, with different particle sizes, were evaluated in this study
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