By KAI ICHINO/ Staff Writer
October 28, 2024 at 08:00 JST
A concrete material, created by compressing calcium carbonate, is named “calcium carbonate concrete (CCC)” by its development team. Photo taken Sept. 30 at the University of Tokyo (Kai Ichino)
Researchers in Japan found a way to make concrete that effectively emits no carbon dioxide (CO2) during the production process.
The team of scientists, primarily from the University of Tokyo and Hokkaido University, said the substance absorbs more CO2 than it releases.
They are now seeking to gain Building Standards Law certification for the material with an eye toward putting the material into practical use for construction by fiscal 2029.
“The minimum requirement for commercialization has already been fulfilled,” said Takafumi Noguchi, a professor of studies on construction materials at the University of Tokyo, who is part of the team.
The production of cement, a key ingredient for concrete, inevitably leads to CO2 emissions.
To make concrete, limestone, or calcium carbonate, is mixed with clay and other materials and then calcined at high temperatures, so CO2 is released via the thermal decomposition of calcium carbonate.
Additionally, burning fossil fuels to achieve the required calcination temperature of 1,450 degrees results in further CO2 emissions.
Because of that, CO2 emissions linked to the cement industry account for 4 percent of the overall total nationwide.
The research team started looking at ways to develop a concrete variant whose manufacturing process does not entail high-temperature calcination.
Under this alternative production method, concrete waste is pulverized and exposed to CO2, with the aim of creating calcium carbonate from the calcium in the waste.
It is then shaped and compressed so the calcium carbonate particles bond and solidify. Heat is applied in the final stage to complete the process.
The scientists discovered that the concrete material produced using this technique emits less CO2 than it absorbs.
In their Sept. 30 announcement, the team members told a news conference that their type of concrete meets the strength criteria specified by the Building Standards Law.
The researchers are now evaluating the concrete material’s performance when combined with steel pipes and other fittings for use in building pillars.
Noguchi said the team will work to improve production efficiency while ensuring there is no compromise in quality of the material.
PHOTO CAPTION
A concrete material, created by compressing calcium carbonate, is named “calcium carbonate concrete (CCC)” by its development team. Photo taken Sept. 30 at the University of Tokyo (Kai Ichino)
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