Effect of Biochar Quality in the Performance of Biochar-Modified Binder: Fid-Bau Portal

Effect of Biochar Quality in the Performance of Biochar-Modified Binder

Sanchez, Xiomara / Varamini, Sina / Bronson, Benjamin

The use of sustainable additives in asphalt is gaining increasing interest, considering Canada’s carbon reduction strategies. Biochar could be one of the additives allowing mix designers to reduce the equivalent carbon of a mixture. Biochar is an additive obtained from renewable sources, but the effect on the performance of asphalt is not thoroughly understood, especially considering that feedstock sources and pyrolysis technologies are diverse, yielding biochars with different chemical and physical characteristics. In this study, the effect of two different types of wood biochar on the characteristics of asphalt cement at varying percentages of 5% and 10% biochar by the weight of the binder was investigated. The binder grade of PG 58-28 was used with no prior modifications (i.e. straight-run asphalt). Binder characterization included a frequency sweep test of the original, short-term aged and long-term aged binder at temperatures from 45 to 75 °C to study the viscoelastic properties. Additionally, Fourier Transformed Infrared Spectroscopy (FTIR) was used to determine the impact of aging on the unmodified and the four Biochar-Modified Binders (BMB). The results indicate that the biochar seems to impart high-temperature stiffness, resulting in increased rutting performance as indicated by the Superpave parameter of G*/sin(delta). However, intermediate-temperature stiffness was increased, implying that it is likely more susceptible to fatigue cracking. Also, the content and type of biochar impact its effect on the oxidative ageing of the binders. Overall, this study demonstrated that the type of biochar influences the performance of the binder, and those parameters should be considered to understand the effect and determine the dosage of biochar to asphalt.