In view of the fact that biochar can absorb 23% of its carbon dioxide by weight from the air, in a proof of concept study, scientists from Washington State University injected environment-friendly biochar into ordinary cement to obtain a new type of environmental cement with negative carbon, and its strength is equivalent to ordinary cement. This research achievement, published in the latest issue of the Materials Express magazine, is expected to significantly reduce carbon emissions in the cement industry. The annual production of concrete worldwide exceeds 4 billion tons. Manufacturing ordinary cement requires high temperature and combustion of fuel, and the limestone used in cement production also decomposes to produce carbon dioxide. Therefore, the cement industry is one of the most energy and carbon intensive industries among all manufacturing industries, and its carbon dioxide emissions account for about 8% of the global total carbon emissions from human activities. Previously, scientists had added biochar (a type of charcoal made from organic waste) to cement in the hope of making it more environmentally friendly and reducing carbon footprint. However, the results showed that even adding 3% biochar significantly reduced the strength of cement. In the latest study, after strengthening biochar with cement wastewater, scientists at Washington State University added up to 30% biochar to the cement mixture. Research has shown that after 28 days, the compressive strength of the obtained paste is equivalent to that of ordinary cement. The research team explained that the alkalinity of cement wastewater is strong, but it is also a valuable source of calcium. A synergistic effect occurs between highly alkaline wastewater containing a large amount of calcium and biochar rich in many pores, causing calcium carbonate to precipitate on or into biochar, enhancing its performance while also enabling it to capture carbon dioxide from the air. Researchers say that most teams can only add 3% biochar to cement, but they have shown that higher doses of biochar can be added to cement. Their newly developed new type of cement may be able to store carbon dioxide for a lifetime. When used on roads, the 'lifespan' of these cement is 30 years, and when used on bridges, its lifespan is 75 years. (New News Agency)
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