A new kind of concrete could reduce emissions from the construction industry. Calcium carbonate concrete is made from waste concrete and carbon dioxide from the air or industrial exhaust gases. It shows promise as a future construction material, especially in places where natural resources are limited.
The modern world is built from concrete. Every tall building in every city on Earth uses the durable and versatile material to give it shape and strength.
The concrete industry therefore is enormous, and this comes at a cost: It is estimated that around 7 percent of the world’s carbon dioxide emissions come from the manufacture and use of cement, the main component of concrete. And a large proportion of this 7 percent is due to the necessary use of calcium, which is usually obtained 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 found a way to take waste concrete and captured carbon dioxide, and combine them in a novel process into a usable form of concrete called calcium carbonate concrete.
Inspired by the way some aquatic organisms harden into fossils over time, Maruyama wondered if the same process that forms hard calcium carbonate deposits from dead organic matter could be applied to concrete.
Calcium is essential for the reaction between cement and water to form concrete, and Maruyama saw this as an opportunity to investigate a less carbon-intensive way of performing the same function.
“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.”
Calcium carbonate is a very stable material, so makes for a durable construction material. And the ability to recycle large quantities of material and waste is a great benefit. However, calcium carbonate concrete cannot replace typical concrete at present.
It is not quite as strong as typical concrete, though for some construction projects, such as small houses, this would not be a problem. Also at present, only small blocks a few centimeters in length have been made.
“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.”
- 33Recently, laser scientists at the Center for Relativistic Laser Science (CoReLS) within the Institute for Basic Science (IBS) in South Korea realized the unprecedented laser intensity of 1023 W/cm2. This has been a milestone that has been pursued for almost two decades by many laser institutes around the world. An…
- 33In a new study, North Carolina State University researchers found that an outdoor science program was linked to higher average science grades and an increase in a measure of science knowledge for a group of fifth grade girls in North Carolina. The findings, published in the International Journal of Science Education,…
- 30Science & Technology News aims to be one of the top and most trusted information providers in the sector. We publish stories ranging from technological advancements here on Earth and up to what is beyond in the realms of the unknown galaxies – and everything in between. This news website is…