https://www.nedo.go.jp/news/press/AA5_101955.html
As part of the “Establishment of Carbonation Technology Using Diverse Calcium Sources” initiative, Sumitomo Osaka Cement Co., Ltd. and Taisei Corporation have completed a demonstration regarding the manufacturability, productivity, quality, and durability of CO2-sequestering concrete products made using “artificial limestone,” a key output of this Project.
CO2-sequestering concrete products—capable of sequestering up to approximately 110 kg of CO2 per cubic meter—were utilized in a public works project directly supervised by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). Monitoring conducted over a period of approximately three years demonstrated that the concrete successfully achieves a balance between environmental performance and structural performance.
Moving forward, the companies will work to further advance this technology, expand its scope of application, and establish relevant guidelines. They will conduct additional on-site construction across diverse environments and conditions while continuing technological development to achieve further CO2 reductions, thereby contributing to the reduction of greenhouse gas emissions in the social infrastructure sector and the realization of carbon neutrality by 2050.
Cement and concrete materials that use calcium as an alkaline source hold great promise for significant CO2 reduction; this is because they possess high CO2 sequestration potential, and the resulting carbonates are chemically stable—meaning they allow for long-term CO2 mineral sequestration. Meanwhile, the construction sector faces a demand not only to reduce CO2 emissions during material manufacturing and construction work but also to implement carbon recycling technologies that utilize captured CO2 as a resource. Concrete is an essential material for social infrastructure, making its decarbonization a critical challenge. Against this backdrop, this project has focused on developing technologies to sequester and repurpose captured CO2 as artificial limestone for use in cement and concrete materials.
In this demonstration, concrete products incorporating artificial limestone were deployed in October 2022 at two construction sites managed directly by the Ministry of Land, Infrastructure, Transport and Tourism. Selecting distinct environmental conditions—a cold region and a tunnel interior—the team implemented U-shaped gutters with removable lids at the “Naruse Dam Quarrying Site” (Akita Prefecture) and rectangular channels with vertical walls at the “Arashima No. 2 Tunnel Construction Site” (Fukui Prefecture) (see Figures 1–3). Through approximately three years of on-site monitoring and various tests, the project demonstrated the feasibility of balancing CO2 sequestration with practical utility in terms of manufacturing productivity, quality, and durability.
Four types of concrete with varying CO2 sequestration capacities were utilized, enabling selection based on specific applications and performance requirements. We confirmed that up to approximately 110 kg of CO2 can be sequestered per cubic meter of concrete, demonstrating that the material achieves a balance between environmental and structural performance.
The concrete products were manufactured using conventional equipment and production cycles, and they met the same inspection standards as standard products for shipment. We confirmed that the technology can be implemented without the need for major equipment upgrades or process changes.
We verified the durability of the CO2-sequestering concrete products while the structures were in service. Testing took place in two challenging environments: a cold region prone to freeze-thaw deterioration, and a tunnel interior where carbonation—accelerated by CO2 in vehicle exhaust—was a concern. After approximately three years of on-site monitoring and sampling tests, no cracking or surface spalling was observed, and there was no evidence of strength loss or rebar corrosion.
In parallel with this demonstration, the Green Innovation Fund project involves evaluating the material properties and workability of concrete using artificial limestone, as well as assessing the structural performance of structures built with this concrete. Efforts are also underway to formulate design methods and technical guidelines and to advance standardization. Some of the project’s findings have already been incorporated into the revised Japanese Industrial Standards (JIS) for cement, updated in March 2026. Starting this fiscal year, the project has transitioned from a commissioned project to a subsidized project (operational phase: FY2026–2030). Moving forward, we will continue to advance this technology, expand its scope of application, and develop relevant guidelines during this project phase. We will further accelerate the effective utilization of CO2—aiming for full-scale adoption in social infrastructure sectors, including public works—thereby contributing to the realization of a carbon-neutral society.