Volume 1 Issue 1 (2025): In Progress

The environmental burden of cement production, responsible for nearly 7% of global CO₂ emissions, has intensified the search for low-carbon, resource-efficient alternatives in the construction sector. Biochar, a carbon-rich byproduct derived from the thermochemical conversion of agricultural and urban biomass, has emerged as a multifunctional additive in both cementitious and non-cementitious systems. Its high porosity, alkaline pH, and stable carbon content enable improvements in hydration, mechanical strength, thermal insulation, and durability, while simultaneously offering long-term carbon sequestration. This review critically evaluates the morphological, physicochemical, and functional characteristics of biochar and its effects on cement-based materials, drawing from over 127 published studies. It also highlights the potential of hydrochar, produced through hydrothermal carbonization, as a complementary material in low-carbon construction systems, although research in this area remains limited. Key parameters such as feedstock type, pyrolysis conditions, particle size, and dosage are identified as major factors influencing performance. Beyond technical performance, the use of biochar aligns with circular economy principles by valorizing organic waste streams, reducing reliance on virgin cement and aggregate resources, and enabling industrial symbiosis. Emerging applications in thermal and acoustic panels, multifunctional coatings, and lightweight composites further reinforce its versatility. However, challenges remain regarding workability, performance variability, scalability, and the lack of standardized production and application protocols. Future directions include the standardization of biochar characteristics, large-scale durability validation, integration with life cycle assessment (LCA), development of technical guidelines, and cost–benefit analyses. Overall, biochar and hydrochar represent viable strategies to decarbonize the construction sector and promote sustainable material flows in alignment with global climate and resource-efficiency goals.

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