A Review on Biochar-Concrete: Production, Properties, and Sustainability

Abstract

The construction industry is a major contributor to global CO₂ emissions, with concrete production alone accounting for nearly 7% of anthropogenic output. As the need for sustainable materials grows, biochar-concrete composites have emerged as a promising solution, offering both performance enhancement and long-term carbon sequestration. Biochar, produced through biomass pyrolysis, exhibits properties such as high porosity, a stable carbon structure, and reactive surface groups, which enhance mechanical performance and provide environmental benefits when used appropriately in concrete. Its effectiveness depends on factors such as feedstock type, pyrolysis temperature, and processing conditions, which influence its physical and chemical characteristics. While low-temperature biochars enhance bonding, high-temperature ones offer better durability and stability. Incorporation at optimal dosages (1–5%) can improve strength, reduce shrinkage, and enhance insulation, although excessive amounts may negatively impact workability and integrity. Biochar’s role in sustainability is further supported by its potential for carbon storage and alignment with circular economy goals. Proper feedstock selection and process control are crucial to ensure both safety and optimal performance. This review consolidates current research, highlights existing knowledge gaps, and proposes future directions for the use of biochar in cement-based systems.