Biochar concrete: a new technique for carbon sequestration

摘要: Carbon sequestration, including geological, oceanic, and terrestrial ecosystem sequestrations, plays an important role in mitigating global warming. However, the applications of geological and oceanic sequestrations are limited owing to high costs and technique complexity. In this study, a new sequestration technique,biochar concrete, was developed. Nine different percentages (0%-30%) of biochar were used to replace cement in concrete production, and the performance and carbon sequestration of the resulting concrete were investigated. The results show that the compressive strength of the biochar concrete increased with increasing biochar amounts of 0%-5%. The strength of the biochar concrete meets the national standard for replaced cement amounts of 5%-30%. Further, the durability of the biochar concrete increased with increasing biochar amounts of 0%-25%. The porosity and water absorption of the biochar concrete exhibited a slight increase, whereas the slump experienced a slight decrease with increasing biochar amount. If biochar concrete is applied to new buildings and in the renovation of existing buildings in China, the biochar made from organic wastes that will quickly decompose and discharge 1,060,000,000 tons CO2, will be permanently sequestrated in concrete, which is equivalent to 1.5% of a standard forest area. Moreover, biochar applied to concrete can also decrease the consumption of cement; hence, saving energy and reducing the discharge of CO2 in cement production.