The surprising properties of smart concrete

Concrete is everywhere around us, it goes into the construction of ¾ of our houses. In CERIB, the Centre for Studies and Research of the Concrete Industry, a hundred engineers and researchers working to improve its properties, but they are not the only innovation in the field.

In today’s inner cities, the concrete architecture represents pollution and gray, but the concrete inventions could change that. It could become bright, durable and acquire new properties. Transform the public impression through innovative concrete spaces, this is the goal of researchers from the University of Kassel in Germany: the benches can reflect light to see better at night, the tunnel could be light to improve safety and the quayside may be reflective to better guide passengers…

The initial project, which brought together researchers from the university, was to develop a concrete that reflected light. Thus is born the first building material both reflective and non-flammable, since the duo filled ideas. To test and put into practice, the researchers created an interdisciplinary laboratory at the University of Kassel. Their goal is the development of cheap high-tech materials; that is to say, give a new functionality to simple and familiar materials such as wood, paper, stone or concrete.

Concrete is composed of cement, water, sand and gravel. On mixing these four elements concrete is obtained. You can add a variety of ingredients to this basic recipe, such as dyes or so to make reflective glass beads concrete. These beads are used to reflect the light and spread them evenly over the surface; the team developed a special form. Researchers still need a formwork for pouring the concrete into it, because it is liquid at first.

For demonstrations, the researchers prepare mini formwork manually, on an industrial scale; the process is mechanized to avoid additional costs. Following numerous experiments, the researchers have developed a new concrete called “conductive concrete,” very sensitive to touch that can turn on the light. Looking below the installation one can understand how it works: a bulb, cabals and a programming unit. What is essential is that there is only one cable connected to the concrete; the concrete is the sensor that is sensitive to touch.

Soon entire walls will be touch-sensitive, but the ideas of university researchers go even further. Their latest project is a concrete that produces electricity. How does it produce electricity? The answer is surprisingly simple. It is sufficient to cover the conductor with a layer of titanium dioxide (TiO2) and a layer of concrete blackcurrant juice, added to the end of a glass plate which serves as a second conductor and an iodine solution, a small current power can then be found, thus becomes a conductive concrete energy producer. To summarize, it is the combination of a technique that already exists: the Grätzel cell, but mixed into concrete; concrete is transformed into a photovoltaic panel. The problem for now is that the substances are depleted quickly.

For this, the German researchers went to the Netherlands to meet a Dutch researcher at the Polytechnic University of Delft; known to extend the life of concrete by incorporating bacteria. He also works on concrete, his particularity is that he is a biologist and he invented a “self-repairing concrete”, that ca repair its own cracks. How? Thanks to bacteria capable of producing limestone.

The bacteria are not active at the beginning, they are asleep, but if the concrete develops cracks, water gets inside and awakens bacteria, and then they start to eat the food (already mixed into the concrete during its formation) and transforms it into limestone that fills the crack.

The Dutch researcher also has different bacteria that produce light and electricity that could help German researchers solve their problems with photovoltaic concrete. In case of power failure, when people are in the dark, these bacteria could provide signals on the walls and for example indicate the exit of a building or perhaps other cosmetic applications.

If the project of both universities succeeded, the facades would soon be capable to fed buildings with energy, it remains to be seen when this innovation will be found on the market.

 

Hakim BouarabaHakim BOUARABA

Etudiant en Master 2 Commerce électronique à l’Université de Strasbourg, je suis passionné par le domaine du numérique, les innovations technologiques et le droit de l’internet.

 

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