Bamboo-ash concrete absorbs carbon dioxide and exceeds standards
Researchers tested concrete mixes with bamboo biochar replacing cement at up to 1.5% and zeolite replacing fine aggregate at up to 50%.
Researchers at Mepco Schlenk Engineering College in India have developed a concrete mixture that not only captures carbon dioxide but also improves upon the strength of conventional concrete. This innovation utilizes zeolite and bamboo biochar, two materials known for their gas-adsorption properties, to enhance the environmental profile of concrete, a material traditionally associated with high CO₂ emissions.
Concrete production is a major source of carbon emissions due to the energy-intensive process of heating raw materials and the chemical reactions involved in producing clinker. The Indian research team, led by civil engineer Srinivasan Revathi, explored the potential of zeolite and bamboo biochar to address these issues. Zeolite, a volcanic mineral, and bamboo biochar, a carbon-rich material, were integrated into the concrete mix, replacing traditional components without compromising structural integrity.
The team tested various formulations of M35 grade concrete, commonly used in infrastructure. The optimal mix, designated ZB5, included 50% zeolite as a fine aggregate replacement and 1% bamboo biochar as a cement substitute. This formulation achieved a compressive strength of 38.49 MPa, a 7.48% increase over standard concrete, and a split tensile strength of 4.39 MPa, a 15% improvement.
Beyond strength, ZB5 demonstrated notable carbon-capture capabilities. In a controlled environment, the mixture absorbed 1.2 grams of CO₂ per day, with carbon penetration reaching 15 millimeters over a week. The combination of zeolite's microporous structure and bamboo biochar's carbon content facilitates this dual function, allowing the concrete to serve as both a building material and a carbon sink.
The researchers suggest that ZB5 could be particularly effective in applications like concrete pavements, highway parapet walls, and sewer pipelines, where CO₂ levels are elevated. These structures would not only fulfill their engineering roles but also contribute to environmental remediation by absorbing carbon from the atmosphere.
While the current findings are promising, further research is needed to assess the long-term durability and carbon absorption of ZB5 in real-world conditions. Future studies will explore the material's performance across different grades and mortar types, as well as the potential benefits of pre-soaking the biochar. If successful, this approach could transform the construction industry by providing materials that actively reduce environmental impact.
The study results are detailed in the publication: Srinivasan Revathi, Dobson Alice Elizabeth Tania, Sutharson Ancy Shadin, Jegatheesan Keerthana. Effect of zeolite and bamboo biochar as CO2 absorbant in concrete. Carbon Research, 2024; 3 (1) DOI: 10.1007/s44246-024-00116-1.
Source: Biochar Feed