Japan creates concrete that does not emit CO2

According to a reporter in Tokyo, researchers in Japan have just announced that they have found a way to make concrete that emits almost no carbon dioxide (CO ₂ ) during the production process.

The team of scientists, mainly from the University of Tokyo and Hokkaido University, said the concrete material absorbs more CO2 _than it emits. They are now seeking approval from the Building Standards Law for the material, with the goal of putting it into practical use in construction by fiscal 2029.

Researchers in Japan have found a way to make concrete that emits almost no carbon dioxide during production. (Photo: asahi.com).

According to Takafumi Noguchi, professor of building materials research at the University of Tokyo, a member of the research team, the minimum requirements for commercializing CO2-emitting concrete _have been met.

Currently, the concrete production process cannot avoid emitting _CO2 .

• First , the production of cement, a major component of concrete, inevitably leads to CO ₂ emissions . The process of firing limestone or calcium carbonate mixed with clay and other materials to make concrete also releases CO ₂ due to the thermal decomposition of calcium carbonate.
• In addition , burning fossil fuels to reach the required firing temperature of 1,450 degrees Celsius also increases CO _{2 emissions. Therefore, CO 2} emissions from the cement industry are very large and account for about 4% of Japan's total emissions.

To reduce those emissions, scientists have sought to develop a type of concrete that does not require high-temperature firing. In this alternative production method, concrete waste is crushed and exposed to CO ₂ , which creates calcium carbonate from the calcium in the waste. The mixture is then shaped and compressed so that the calcium carbonate particles bond and solidify. Heat is used in the final stage to complete the process.

Scientists have shown that concrete produced using this technique emits less CO2 _than it absorbs.

In an October 30 announcement, team members said their concrete meets the durability criteria set by the Building Standards Act. Researchers are now evaluating the performance of the concrete material when combined with steel pipes and other accessories for use as building pillars.

Professor Noguchi said the team will work to improve production efficiency while ensuring that the quality of the material is not affected.