Application potential analysis of biochar as a carbon capture material in cementitious composites: A review

In recent years, emissions of carbon dioxide in the atmosphere have been increasing, leading to increasingly severe global warming. In the construction industry, the increase in cement production is one of the main sources of CO2 emissions. Cementitious composites can sequester CO2 in calcium carbonate precipitates through carbonation reactions, but their carbon sequestration efficiency is very low due to the slow diffusion rate of CO2 in the cement matrix. To reduce the net CO2 emissions during concrete production, a feasible option is to enhance its carbon capture performance through accelerated carbonation curing (ACC) and CO2 capture and storage (CCS) technologies. Biochar has a strong adsorption capacity for CO2, its production process is green and low-carbon, and its production cost is low, which has high economic benefits. Many studies have applied biochar as cementitious composites in the construction industry to improve the mechanical properties, durability and functionality of cementitious composites. Additionally, biochar is a potential carbon capture material that can effectively improve the carbon sequestration performance of cementitious composites. In this review, the latest research progress of biochar in cementitious composites in recent years is reviewed, and the mechanical prop-erties, durability and carbon sequestration performance of biochar-cementitious composites were analyzed. Additionally, the mechanism of the synergistic effect of biochar and the carbonization reaction in concrete and the effect on the carbon capture ability of cementitious composites were also investigated.