As part of NEDO’s Green Innovation Fund project “Development of concrete manufacturing technology using CO2”, Takenaka Corporation, together with Kajima Corporation and Denka Corporation, will develop carbon negative concrete that emits less than zero carbon dioxide (CO2) during the concrete manufacturing process. They have developed a concrete product called CUCO-precast material for construction that reduces, fixes, and absorbs CO2. This material can reduce CO2 emitted during the manufacturing stage by more than 80% compared to general concrete.
This material is available in four types with different combinations of technologies that reduce, fix, and absorb CO2, and all of them will be used in the Event Hall Building at the Osaka/Kansai Expo 2025.
The three main technologies applied to this material are:
 Technology to reduce CO2 emissions
This technology reduces CO2 emissions by approximately 60% by applying ECM cement, which uses pulverized blast furnace slag powder, which has low CO2 emissions, instead of regular cement.
 Technology to fix CO2
This technology stores CO2 by fixing CO2 in the calcium contained in concrete demolished materials and using it as concrete aggregate or fine powder (CCU material).
 Technology to absorb CO2
This technology absorbs and fixes CO2 after hardening by mixing LEAF, a special admixture with cement that has the properties of efficiently absorbing CO2 and making the hardened material dense.
CUCO is a registered trademark of Takenaka Corporation, Kajima Corporation, and Denka Corporation.
Blast furnace slag powder is a slag produced during the production of pig iron in blast furnaces at steel plants is quenched with water and pulverized.
ECM Cement: ECM stands for Energy/CO2 Minimum, and is a cement that reduces energy consumption and CO2 emissions during manufacturing by replacing approximately 60% of regular cement with pulverized blast furnace slag, an industrial byproduct. This is a registered trademark of Takenaka Corporation.
CCU material stands for Carbon Capture and Utilization, and in this technology it refers to concrete materials manufactured by utilizing (fixing) CO2 as a resource.
LEAF is an abbreviation for Long-life, Environment, Add, Functions, and is a special admixture that has the property of densifying the hardened material by efficiently absorbing CO2 and hardening.