How CO2 Emissions Can Be Reduced With Self-Healing Concrete

Fascinating facts about nature and sustainability

Published in

Climate Conscious

3 min readFeb 25, 2022

Dandelion growing from cracked concrete — A dandelion growing in cracked concrete (credit: Evgenii Emelianov on Shutterstock)

Conventional concrete is one of the most used building materials in the world. Over 30 million tons of concrete are being produced and used every year. This is about the weight of six Pyramids of Giza. A major disadvantage of this building material is that it is environmentally unfriendly: the production of cement, which is a main component of concrete, uses 10–15% of total industrial energy and causes 5–8% of the CO2 emissions caused by humans.

Another major disadvantage is that conventional concrete easily cracks. Cracks can appear when the temperature changes and the concrete expands or contracts. Gases such as air and liquids such as rain can flow in, causing the concrete structure to decay. Not only does the concrete not last as long, but also the metal inside the concrete can rust. This means that (micro-)cracks can cause structural failure and make the building less durable and safe.

One solution is to renovate and restore the concrete structure by closing the cracks. But this is not easy, as cracks are not always well-visible. Also, this requires continuous maintenance and costs a lot of money. So, to make sure the structure is more durable and safe, and make concrete more environmentally friendly, self-healing concrete has been developed. This is how concrete can heal itself and reduce CO2 emissions:

How concrete can heal itself

Conventional concrete is not able to heal itself, but bioconcrete can. Bioconcrete is concrete that contains bacteria in the form of spores. When these spores get into contact with water, because water flows in a crack, they become active and produce crystals made of calcium carbonate. Calcium carbonate is a well-known substance, as eggshells mostly consist of it and it is used as a meal supplement to treat calcium deficits. The number of crystals produced by these bacteria grows until the whole crack is closed.

Picture of concrete with cracks that are closed with carbon carbonate. — Concrete that has healed itself (credit: studiojaskrawo on Shutterstock)

How self-healing concrete reduces CO2 emissions

Closing cracks with calcium carbonate is environmentally friendly, not only because it is natural, but it also helps reduce CO2 emissions. CO2 emissions are reduced, because:

The life span of concrete structures increases, so less concrete needs to be produced. As mentioned before, producing cement causes a lot of CO2 emissions.
The concrete does not need inspection and restoration, which also requires material and energy.
CO2 is consumed in the calcium carbonate: carbon dioxide and calcium hydroxide (slaked lime) form calcium carbonate and water as can be seen in the chemical reaction CO2 + Ca (OH)2 → CaCO3 + H2O.

Conclusion

So, CO2 emissions can be reduced with self-healing concrete, as less concrete needs to be produced, no material and energy are needed for inspections and restoration, and CO2 is consumed to produce the material that closes the cracks.

About the author

Dr. Erlijn van Genuchten is a an internationally recognized environmental sustainability expert. She is a science communicator, helpings scientists in the fields of nature and sustainability increase the outreach of their results and allowing us all to put scientific insights into practice and contribute to a sustainable future. Erlijn has inspired thousands of people around the world — for example — by supporting the United Nations with her expertise, her book “A Guide to A Healthier Planet” published by Springer Nature, and her posts on social media.