Concrete leaves behind a huge carbon footprint, so any technology that improves its capabilities and makes this definitely longer lasting concrete has the potential to do a lot of good for the environment.
This has led to the creation of self-healing concrete, which repairs its own cracks within 24 hours using carbon dioxide absorbed from the atmosphere. Tiny cracks appearing in concrete may not look serious, but they can bring serious consequences, such as compromising the structural integrity of a building, and if water gets into them, the strength of the concrete is also compromised. This is why scientists came up with the idea of creating a self-healing concrete that will repair the damage as long as it is small and relatively easy to do so. They’ve tested a lot of interesting solutions over the years, so we’ve already seen ideas for filling cracks with sodium silicate, bacteria, and even fungi.
Now another one is coming to them, and its creators at Worcester Polytechnic Institute assure us that it’s cheaper and more effective. And interestingly, the researchers here were inspired by the human body, or more specifically, by an enzyme in red cells called carbonic anhydrase, which is able to rapidly transfer carbon dioxide from cells into the blood. – We turned to nature looking for the fastest transfer of CO2 and that is the CA enzyme. The enzyme in our bodies reacts surprisingly quickly, so it could be used as an efficient mechanism to repair and strengthen concrete structures, explains study author Nima Rahbar. For things to have a chance to work, however, the enzyme must be added to the cement before it is mixed with water and poured onto the target site.
If this happens, when a small crack appears in the concrete, the enzyme reacts with CO2 in the air to produce calcium carbonate crystals that mimic the characteristics of concrete and immediately refill the cracks. In tests, the researchers demonstrated that their solution could repair microcracks in concrete in just 24 hours, which is a major advance because the previously mentioned bacteria were more expensive to use and took as long as a month to repair. And while the amount of CO2 absorbed in the process is small and probably insignificant in global terms, in the long run it could have a huge environmental impact by extending the life of a material whose production is not very eco-friendly. Especially since, according to its authors, it extends the life of concrete from 20 to even… 80 years!