https://www.nedo.go.jp/news/press/AA5_101721.html

In  Japan, approximately 8 million tons or approximately 20% of domestic cement demand are used annually for ground improvement.

Takenaka, Kajima and Denka Corporation are developing carbon negative concrete CUCO® that emits virtually no carbon dioxide (CO2) during the concrete manufacturing process.  Takenaka Corporation has recently developed a “CUCO®-CO2 fixation ground improvement method which uses CO2 fixation fine powder (CCU material) made by carbonating fine powder recycled from concrete demolition debris. This reduced CO2 emissions by approximately 5% compared to conventional ground improvement methods. The carbon negative concrete being developed by CUCO® uses technology to “fix” CO2, that is, fixes CO2 in the calcium contained in construction waste (concrete demolition debris) discharged when demolishing concrete and demolished soil improvement materials. CO2 is stored by reusing it as concrete aggregate and CCU material.

This method was applied to part of the ground improvement at the Mitsubishi Miraikan  for the 2025 Japan World Expo (Osaka/Kansai Expo). It was applied to approximately 200m2 of the approximately 600m2 ground improvement area, and it was confirmed that it met the performance requirements as a ground improvement body. The amount of CO2 fixed was approximately 160 kg, reducing CO2 emissions by approximately 5% compared to conventional ground improvement methods.

Image: Mitsubishi Miraikan and photos of ground improvement construction