Reducing emissions from the building sector might be possible with a new type of concrete. Waste concrete and carbon dioxide from the air or from industrial exhaust gases are used to create calcium carbonate concrete.
It has potential as a building material in the future, particularly in regions with a dearth of natural resources. The concrete that makes up the modern world.
The resilient and adaptable material is used to lend shape and strength to every tall building in every city on Earth. Therefore, there is a sizable concrete business, and this has a price: The production and use of cement, which is the primary ingredient in concrete, is thought to be the source of 7% or less of the world’s carbon dioxide emissions.
And a significant percentage of this 7% is because calcium is required, which is often supplied by burning limestone.
A new way to reduce emissions levels caused by concrete use has been proposed and proven to work by Professor Ippei Maruyama and C4S (Calcium Carbonate Circulation System for Construction) project manager Professor Takafumi Noguchi, both from the Department of Architecture at the University of Tokyo. They have discovered a method to combine carbon dioxide capture and waste concrete to create calcium carbonate concrete, a useful kind of concrete.
As well as increasing the strength and size limits of calcium carbonate concrete, it would be even better if we could further reduce the energy use of the production process. However, we hope that in the coming decades, carbon-neutral calcium carbonate concrete will become the mainstream type of concrete and will be one of the solutions to climate change.Professor Takafumi Noguchi
Maruyama was intrigued by how some aquatic animals become fossilized over time and wondered if the same process could produce hard calcium carbonate deposits from organic debris in concrete.
In order for cement and water to react to make concrete, calcium is necessary. Maruyama recognized this as an opportunity to look for less-carbon-intensive ways to carry out the same job.
“Our concept is to acquire calcium from discarded concrete, which is otherwise going to waste,’’ said Maruyama. “We combine this with carbon dioxide from industrial exhaust or even from the air. And we do this at much lower temperatures than those used to extract calcium from limestone at present.”
Since calcium carbonate is a relatively stable substance, it is a reliable building ingredient. Additionally, it is quite advantageous to be able to recycle a lot of garbage and materials. Calcium carbonate concrete, however, cannot currently take the place of regular concrete.
It is not quite as strong as ordinary concrete, but this would not be a problem for some construction projects, such modest houses. Currently, only little bricks that are a few millimeters long have been created.
“It is exciting to make progress in this area, but there are still many challenges to overcome,” said Noguchi.
“As well as increasing the strength and size limits of calcium carbonate concrete, it would be even better if we could further reduce the energy use of the production process. However, we hope that in the coming decades, carbon-neutral calcium carbonate concrete will become the mainstream type of concrete and will be one of the solutions to climate change.”
Funding This research was funded by the NEDO Moonshot project, C4S Research and Development Project, Calcium Carbonate Circulation System for Construction.