Performance Testing of Hot Mix Asphalt Containing Biochar

In recent years, researchers have been able to identify asphalt binder additives, such as polymers and bio-binder, that can enhance the rheological and mechanical properties of asphalt binders. Earlier studies show that utilizing bio-binder as a partial replacement for asphalt binder has shown promising results in both mechanical and sustainability aspects. Biochar additions improved binder viscosity and low-temperature characteristics. Biochar, which is a byproduct of producing bio-binder, has shown enhanced rheological and mechanical properties when used as an additive to the asphalt binder. In this study, the mechanical properties of asphalt mixtures containing Biochar were investigated. In addition, its color degradation was investigated. The Semi-Circular Bending (SCB) test proved to be a suitable test method to analyze the fracture properties of asphalt mixtures. Similarly, the Hamburg Wheel Tracking (HWT) test is efficient in testing for and analyzing the rutting and moisture susceptibility of asphalt mixtures. This study used the SCB and HWT tests to investigate the mechanical properties of asphalt mixtures containing Biochar. The study incorporated conventional (virgin) and rubberized mixtures and investigated the effect of aging as well. The SCB results suggest that adding Biochar helped attain higher strain energy values for virgin and rubberized mixtures after aging. The HWT results showed that the addition of Biochar helped achieve lower rut depth for non-aged mixtures. After aging, and since Biochar reduces the effect of aging, aged Biochar mixtures achieved higher rut depth (less hardening) compared to virgin aged mixtures. As for color degradation, the addition of Biochar helped to decrease the color degradation of the asphalt mixture compared to the control mixture