Kajima CO2-SUICOM Carbon-Capturing Concrete

Kajima Corporation is a Japanese general contractor that runs the Kajima Concrete Base programme of low-carbon concrete technologies. CO2-SUICOM, which Kajima describes as the world's first carbon-capturing concrete, was jointly developed with The Chugoku Electric Power Co., Denka and Landes Co. and is cited in Japan's Green Growth Strategy for carbon neutrality by 2050.

More than half of the cement is replaced with gamma-C2S, a material that hardens by reacting with CO2 instead of water, plus low-CO2 industrial by-products. After mixing, precast elements are cured in a chamber fed with CO2-rich gas such as thermal power plant exhaust, so the concrete captures and permanently traps CO2. Products include paving blocks, stay-in-place formwork for bridge piers and large block retaining walls, and the CUCO-SUICOM variant uses CO2 captured from the air by Kawasaki Heavy Industries' direct air capture system. Buyers are expressway operators, public works owners and developers.

• Gamma-C2S binder: replaces more than half of cement with a material that hardens by absorbing CO2.
• CO2 curing chamber: precast elements cure in CO2-rich exhaust gas such as from thermal power plants.
• Carbon-negative balance: about minus 18 kg CO2 per cubic metre net emissions.
• CO2-SUICOM (E) grade: surface-layer carbonation enables large precast members to cure in a short time.
• Product range: paving blocks, stay-in-place pier formwork and large block retaining walls.
• DAC-based CUCO-SUICOM: blocks made with CO2 captured from the atmosphere with Kawasaki Heavy Industries.

Expressway and bridge projects in Vietnam can use CO2-SUICOM retaining wall blocks and stay-in-place pier formwork to lower embodied carbon. Coal power plants can partner with precast factories to route flue gas into curing chambers. Urban developers can lay carbon-negative paving blocks in public spaces and industrial parks.

Per cubic metre, CO2-SUICOM emits about 197 kg less CO2 in manufacturing than standard concrete and traps about 109 kg more, a total cut of about 306 kg and net emissions of about minus 18 kg. Each large retaining wall block in the new E grade cuts about 72 kg of CO2. Stay-in-place formwork removes the need for stripping and speeds pier construction. CO2 from power plant exhaust or the air becomes a permanent part of the structure.

Asian governments are pairing carbon neutrality targets with carbon capture and utilisation programmes, and concrete products that permanently store CO2 are a visible use for captured carbon. Vietnam, with many coal power plants and large precast demand for expressways and urban infrastructure, is a candidate market for technologies that turn power plant flue gas into precast concrete.

Kajima Corporation is a major Japanese general contractor. CO2-SUICOM was co-developed with The Chugoku Electric Power Co., Denka and Landes Co.; Kajima also conducts joint research with Nippon Concrete Industries. The DAC-based CUCO-SUICOM work is part of a NEDO Green Innovation Fund project with Kawasaki Heavy Industries showcased at Expo 2025 Osaka.