American researchers at Worcester Polytechnic Institute (WPI) used an enzyme found in red blood cells to create self-healing concrete.
The tiny cracks that form in concrete may not pose an immediate problem to the structural integrity of the structure. But as water penetrates the breaks, the strength of the structure decreases dramatically. The idea behind self-healing concrete is to intervene while the cracks are still tiny. The new technology seals the material to prevent not only catastrophic collapse but also costly maintenance or complete replacement of concrete structures.
To solve the problem, scientists were inspired by the work of the human body; namely by the work of an enzyme in red blood cells called carbonic anhydrase. It is able to rapidly transfer CO₂ from cells to the bloodstream.
The team added an enzyme to the concrete powder before mixing and pouring the material. The experiment showed that when a small crack forms in concrete, carbonic anhydrase interacts with CO₂ in the air. As a result, calcium carbonate crystals are formed, which mimic the characteristics of concrete and quickly fill the crack in the structure.
In tests, scientists have demonstrated that their alloyed concrete repairs millimeter-sized cracks in 24 hours.