Biochar-Enhanced Carbon-Negative and Sustainable Cement Composites: A Scientometric Review

The increasing demand for cement, which is being driven by global urbanization and infrastructure expansion, necessitates sustainable alternatives to be used as construction materials. Cement-based composites, a prevalent construction material, are known for their high carbon footprint. Consequently, exploring sustainable alternatives is urgently needed to curb the environmental impact of the construction sector by capturing carbon dioxide (CO2). Thus, utilizing biochar (BC) in cement-based composites, either as additive or cement, and in aggregate replacement could be a green approach, by producing enhanced composites with the capabilities of CO2 sequestration. This review investigates the BC-modified cement composites by performing a scientometric assessment of the Scopus database and a thorough manual review. A scientometric assessment of Scopus-indexed publications retrieved from 2010–2024 was conducted to highlight key research trends, including influential authors, frequently cited works, countries, and institutions. The findings provide a comprehensive overview of the current situation of BC research and applications in cement-based composites for sustainable construction. The assessment revealed that the Construction and Building Materials journal was the most prolific source of publications (n = 34), followed by Gupta, with S as the most prolific author (n = 11), and China as the leading country in the field (n = 56). It also highlights the emerging areas for the use of BC in the construction sector for sequestering CO2 and potential future directions. Additionally, the review discusses BC sources and BC production technologies and characteristics. It also discusses the influence of BC inclusion on the fresh properties, its mechanical properties, durability characteristics, carbon capture capabilities, and the environmental impacts of modified cement-based composites. It has been noted that BC addition to cement-based composites from 1% to 2% can increase its mechanical performance, whereas, beyond a 5% to 6% replacement, they experienced a decline compared to non-modified composites. BC addition has reduced the flow characteristics of the modified composites due to its porous morphology and hydrophobic nature but has shown improved internal curing and reduced shrinkage. It also improved the microstructure of the cement-based composite through pore refinement, due to the filling ability of the BC particles attributed to its specific surface area and size. Additionally, the carbon sequestration potential of BC can be exploited in cement-based composites to create low carbon or carbon-negative building materials with improved mechanical and durability characteristics. The study also highlights the future directions for further studies and implementation strategies of BC as a sustainable construction material at a large scale.