Plant waste in construction: a review of the use of biochar as a sustainable additive in cement

Currently, cement manufacturing accounts for approximately 8% of global carbon emissions, and the continuously increasing demand driven by population growth makes it impossible to halt production. At the same time, nature offers abundant renewable resources that can be reused to mitigate this environmental challenge. This study presents a systematic review of experimental investigations evaluating the partial replacement of Portland cement with biochar in mortar production. The review compiles and analyzes the tests and findings reported by several authors, focusing on key parameters such as aggregate granulometry, feedstock type used for biochar production, replacement ratios, water absorption, compressive and tensile strength, permeability, and microstructural behavior assessed through X-ray diffraction (XRD) and thermogravimetric and analysis (TGA). The results were compared with the limits established by current construction standards, emphasizing the types of biochar that demonstrated the most favorable performance in mechanical and durability properties.