Dutch microbiologist has developed self-healing concrete

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



Concrete has been used as a building material for over 6000 years, since the time of Ancient Mesopotamia. And until now, it is the most popular building material that allows you to quickly erect buildings of various shapes , and even use 3D printing technology for this . Typically, buildings use reinforced concrete - a combination of metal reinforcement and concrete.

The disadvantage of concrete is that cracks appear in it over time. When water penetrates through them, the reinforcement rusts and the structure loses its strength. 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 concrete.



And all the same, sooner or later it is necessary to carry out a long and expensive repair of concrete structures. And buildings that are, for example, under water, or that store harmful materials inside (toxic industrial wastes, radioactive wastes) are generally very difficult or impossible to repair.

In 2006, a construction engineer turned to the microbiologist Jonkers with a question whether bacteria could be adapted to create self-healing concrete. He managed to solve this problem in three years - and it was quite difficult. The bacterium must survive in a very harsh environment - concrete looks like stone, it is dry, and also it is very alkaline. Bacteria must somehow survive inside the material for years.





Jonkers turned to bacteria of the genus Bacillusthat can exist in an alkaline environment, and their spores survive for decades without food and water. It only remained to provide them with food. Simple 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 biodegradable plastic capsules.

The water entering the slots dissolves the plastic, and the bacteria begin to multiply, eat calcium lactate and produce limestone. Since this process occurs in the places where cracks appeared, limestone closes 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 cost less in construction, will require much less repair and will last much longer.