Concrete is the most common building material in the whole world, and indeed a long-lasting one. But it’s not indestructible, and when it cracks under pressure from, for instance, change in temperature, air or moisture, it’s both dangerous as well as expensive to fix. Cracks developed in concrete allow penetration of salt and water through it that can corrode the steel reinforcements inside it. No one wants a bridge, skyscraper or a dam to suddenly break apart. So, a technique was needed to be developed to cease the cracking and the job was done by two of the researchers at TU Delft, which is a renowned college in Netherlands. They invented a special type of concrete which can heal itself by the use of bacteria which is termed as Bio Concrete. It is also known as self healing concrete or bacterial concrete.
As the pH value of concrete is very high, only the so-called alkaliphilic bacteria are able to survive in this condition. Moreover, the bacteria have to be able to survive the concrete mixer and then they have to wait for years before being able to carry out their restoration work. Bacteria of the bacillus species are perfect for the job. They can survive for decades in a kind of sleep mode, without food or oxygen. In concrete, they will only come to life if water and oxygen are added to it. In other words, if a crack appears in the concrete, they will be able to multiply and produce limestone, thereby closing the cracks. Once the crack is closed up completely, moisture can no longer get into the concrete, so it will not weaken. This type of technique can be used in hydraulic structures like dam.