2025 Expo to exhibit carbon-capturing concrete dome

The special concrete hardens by capturing CO2 in the air and will reduce CO2 emissions in its construction phase by 70 percent compared with a structure built with conventional concrete, according to construction firm Kajima Corp.

But by far most of the CO2 emissions are not caused in the construction phase; they come from the production of cement which uses fossil fuels to heat limestone to 1400 degrees to produce a chemical reaction which itself produces CO2. Kajima's process may reduce the emissions in the construction phase but it is a misrepresentation to suggest that it is a construction method that will capture carbon and even make much dent on the contribution of concrete pouring to CO2 production.