Cement is one of the industries with the carbon footprint of the highest planet: a report of 2018 prepared by Chatham House estimated that this sector contributes 8% of all emissions. New scientific contributions from the Worcester Polytechnic Institute could give a sustainability twist to the sector. They have just achieved self-healing concrete thanks to an enzyme present in red blood cells.
This concrete with the ability to repair itself and fill its cracks without the need for human intervention could considerably extend the useful life of structures and reduce part of the carbon dioxide released into the atmosphere This discovery is no small feat if we consider concrete as the most widely used artificial construction material in the world: almost everything you step on in your day-to-day life is covered by this preparation: bridges, buildings, sidewalks, stations, houses, and roads. Although highly versatile, it is prone to cracking from exposure to water, thermal changes, stress, road salt, and design flaws.
The peer-reviewed study, which has been published in Applied Materials Today, focuses on using an enzyme found in red blood cells to make this self-healing building material that is 4 times more durable than its traditional variant. The savings would come from several fronts: on the one hand, the useful life of the concrete is prolonged, but at the same time, the need for costly repairs or replacements, labor, associated logistics costs, and many other expenses are also eliminated.
This enzyme automatically reacts with atmospheric carbon dioxide to create calcium carbonate crystals, which mimic concrete in the structure, strength, and other properties, filling cracks before they cause structural problems.
“The global use of concrete is ubiquitous,” says Nima Rahbar, associate professor of Civil and Environmental Engineering and lead author of the article, who celebrates this automatic repair to prevent the cracks from growing and requiring replacement. “It sounds like science fiction, but it is a real solution to a major problem in the construction industry,” he says.
The research has been inspired by the process of carbon dioxide transfer in nature. The enzyme with the key to saving our construction industry is carbonic anhydrase (CA), present in red blood cells and rapidly transferring CO₂ from cells to the bloodstream.
When it is added to concrete before mixing and pouring it, it acts as a catalyst, and when a small crack is formed in the enzymatic concrete, this ally connects with the carbon dioxide present in the air, triggering the growth of a new matrix that fills the crack.
“We look in nature to find what triggers the fastest CO2 transfer, and that is the CA enzyme,” says Rahbar, five years behind him researching this innovation. “Because the enzymes in our bodies react with amazing speed, they can be used as an effective mechanism to repair and strengthen concrete structures.”
A process that heals millimeter-scale cracks in 24 hours is quite impressive and effective. This process is extremely interesting considering that each year more than 4,000 million tons of cement are produced. Thanks to this valuable enzyme, the material will be able to preserve its resistance, water tightness, and durability.
The research prediction estimates that self-healing concrete could extend the life of a structure from 20 to 80 years.
Writer: Imaaz Nadeem