Dutch microbiologist developed self-healing concrete

Henk Jonkers of Delft Technical University has developed a system to automatically seal cracks in concrete . In manufacturing, capsules containing bacteria and nutrients are used as one of the material ingredients. In the normal state, the bacteria are inactive. After a crack appears in the concrete, the water that comes in dissolves the capsules and causes the bacteria to live. In the process of life they produce limestone, which clogs the cracks.


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Concrete has been used as a building material for more than 6000 years, since the time of Ancient Mesopotamia. And so far it is the most popular building material , allowing to quickly build buildings of various forms , and even use 3D printing technology for this. Usually reinforced concrete is used for buildings - a combination of metal reinforcement and concrete.

The lack of concrete is that over time, cracks appear in it. When water gets inside through them, the fittings rust and the design loses durability. In winter, the water freezing in cracks expands them and accelerates the wear process. Now they are struggling with this, using various coatings and impregnations, and adding extra reinforcement in attempts to reduce the load on the concrete.



And anyway, sooner or later you have to carry out a long and expensive repair of concrete structures. And buildings that are, for example, under water, or stored inside hazardous materials (toxic industrial waste, radioactive waste) are generally very difficult or impossible to repair.

In 2006, a construction technologist turned to microbiologist Jonkers asking if bacteria could be adapted to create self-healing concrete. He managed to solve this problem in three years - and this was quite difficult. The bacterium must survive in a very tough environment - concrete is like stone, it is dry, and besides, it is very alkaline. Bacteria need to somehow survive inside the material for years.





Jonkers turned to bacteria of the genus Bacillus , which can exist in an alkaline environment, and their spores have survived for decades without food and water. It remained only to provide them with food. Plain sugar would reduce the strength of concrete. After a long search, it was decided to use calcium lactate , and enclose the bacteria along with their food in capsules of biodegradable plastic.

Water entering the crevices dissolves plastic, and bacteria begin to multiply, eat calcium lactate and produce limestone. Since this process occurs in places where cracks have appeared, limestone covers them, preventing further destruction of concrete.



This invention can open a new page in construction, allowing you to build buildings, bridges and other structures that will be cheaper in construction, will require much less repair and will last much longer.