Kajima Corporation (President: Hiromasa Amano), together with Denka Company Limited (President: Toshio Imai) and Takenaka Corporation (President: Masato Sasaki), is developing this technology as the managing company of a consortium implementing the New Energy and Industrial Technology Development Organization's (NEDO) “Green Innovation Fund Project—Project for Development of Concrete Manufacturing Technology Using CO₂—”. As the first result of these efforts, CUCO-SUICOM Formwork, which is made of carbon-negative concrete that emits virtually zero or less CO₂ during the manufacturing process, has now been applied to construction sites for the first time.

The CUCO-SUICOM Formwork is made of concrete that contributes to achieving carbon neutrality by 2050 by improving on CO₂-SUICOM, a technology developed by Kajima Corporation and others that fixes CO₂ in concrete and enables further reduction of CO₂ emissions. Recently, the Ministry of Economy, Trade and Industry (METI), NEDO, and the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) collaborated to apply the CUCO-SUICOM Formwork as a buried formwork*¹ in the construction of a water discharge tunnel ordered by MLIT, which reduced CO₂ emissions by 677 kg/m³ compared with the use of conventional high strength panels, achieving a carbon negative of -62 kg/m³ in real emissions.

*1 Buried formwork is a formwork that is used as part of the structure without being removed after concrete is placed.

Overview of concrete used for CUCO-SUICOM Formwork

CO₂ reduction and fixation are maximized by combining the two technologies of CO₂-SUICOM, which reduces CO₂ by replacing part of the cement with industrial by-products[1] and CO₂ absorption and fixation in concrete through carbonation curing using a special admixture (γ-C₂S)[2], with calcium carbonate, a CCU (CO₂ capture and storage) powder[3].

Application to actual construction

This time, “CUCO-SUICOM Formwork” was applied as a buried formwork in Spillway Tunnel Construction. Among concrete materials, replacing cement with blast furnace slag fine powder, an industrial byproduct, reduced CO₂ emissions by 409 kg/m³, and using special admixture γ-C₂S and calcium carbonate successfully absorbed and fixed 268 kg/m³ of CO₂, for a total reduction of 677 kg/m³ of CO₂ emissions. As a result, the new panel has achieved -62 kg/m³ of CO₂ emissions, which is less than zero in real terms, compared to the use of ordinary high-strength panels (615 kg/m³ of CO₂ emissions).

Since one cedar tree absorbs approximately 14 kg of CO₂ per year, this reduction is equivalent to the amount absorbed by 139 trees.

Buried formwork construction flow

[1] Buried formwork is joined together with steel to form a large format

[2] Erection of large-sized buried formwork

[3] Placement of concrete on back of buried formwork

Future Development

The Consortium CUCO will continue to work in unison to develop and improve CO₂ reduction and fixation technologies to achieve further CO₂ reduction, thereby contributing to the transition to a decarbonized society.

Outline of Construction

・Construction name:

2021-2022 Kusaka River new discharge channel control road maintenance work

・Construction site:

Okina, Hidaka-mura, Takaoka-gun, Kochi, Japan

・Client:

Ministry of Land, Infrastructure, Transport and Tourism Shikoku Regional Development Bureau

・Constructor:

Kajima Corporation

・Use :

Discharge tunnel

・Construction specifications:

(Operation tunnel) 224 m, (Tunnel gate) 1 set

・Construction period:

March 2022 - March 2023