Bamboo-derived Biochar as Partial Cement Replacement in Concrete for Carbon Dioxide Capturing and Sequestration

Abstract

Global urbanization has contributed to heightened carbon dioxide (CO₂) emissions due to extensive cement production for construction purposes. This research explores the viability of biochar as a means of sequestering CO₂. Biochar, a solid material derived from the thermochemical conversion of biomass in a low-oxygen environment, exhibits promising carbon capture capabilities. The primary objective of this study is to develop a concrete mixture design incorporating chemically-activated bamboo biochar as a partial replacement for cement and to assess its capability in capturing and sequestering CO₂. Bamboo biochar was produced at 300 °C and activated using sodium hydroxide. Cement replacement levels of 2 %, 5 %, and 8 % by weight were employed. Cylindrical concrete samples were subjected to compressive testing at 7 and 28 days, while the ability of biochar concrete to adsorb CO₂ was evaluated using an MQ135 gas sensor test. The carbonation depth was determined after subjecting the specimens to a one-month exposure to CO₂. The compressive strength test results confirmed that the 7-day strength of biochar-incorporated concrete was minimally below the standard strength while the 28-day strength was significantly higher. Meanwhile, the gas sensor test affirmed the effectiveness of biochar concrete in adsorbing CO₂, as evidenced by the increase in carbonation depth. These results indicate the potential of bamboo biochar as partial cement replacement in concrete to sequester CO₂ without majorly affecting its compressive strength.