A new kind of concrete made from waste concrete and carbon dioxide from the air

The concrete industry is enormous. But, this industry is responsible for around 7% of the world’s carbon dioxide emissions. A large proportion of this 7% is due to the necessary use of calcium, which is usually obtained by burning limestone.

Now, scientists at the University of Tokyo have found a new way to reduce emission levels caused by concrete. Their solution is a new kind of concrete made from waste concrete and carbon dioxide from the air or industrial exhaust gases. Dubbed Calcium carbonate concrete, the concrete shows a future construction material, especially in places where natural resources are limited.

The way includes using waste concrete and captured carbon dioxide and combining them in a novel process into a usable form of concrete called calcium carbonate concrete.

Professor Ippei Maruyama from the Department of Architecture at the University of Tokyo said, “Our concept is to acquire calcium from discarded concrete, which is otherwise going to waste. We combine this with carbon dioxide from the 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.”

Professor Takafumi Noguchi, from the Department of Architecture at the University of Tokyo, said, “It is exciting to make progress in this area, but there are still many challenges to overcome. 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.”

Journal reference:

1. Ippei Maruyama, Wataru Kotaka, Bui Ngoc Kien, Ryo Kurihara, Manabu Kanematsu, Hikotsugu Hyodo, Hiroshi Hirao, Ryoma Kitagaki, Masaki Tamura, Masato Tsujino, Satoshi Fujimoto and Takafumi Noguchi, “A New concept of calcium carbonate concrete using demolished concrete and CO2,” Science: October 8, 2021, DOI: 10.3151/jact.19.1052.