Bio concrete repairs itself from damage by yourself


01/11/2012

Experimental concrete, which is self-plug the emerging cracks in it, will be tested in the open air.

This concrete contains limestone-producing bacteria, which are activated by corrosive rainwater penetrating inside. This material may extend the service life of concrete, allowing significant savings.

This work is carried out in the Delft University of Technology, The Netherlands.

This idea originated with microbiologist Henk Jonkers and concrete technology specialist Eric hose.

If all goes as planned, the commercialization of the system will begin in 2-3 years.

Concrete is the most widely used construction material in the world. But he is prone to cracking, so the need to strengthen the structure with steel.

"Microcracks" are expected result of solidification and does not directly lead to a loss of strength. Cracks of about 0.2 mm are within the permitted rules in the concrete industry. But over time, the water and dissolved therein aggressive chemicals fall into them and corrode the concrete. "To extend the life of concrete structures, it is important to patch up these cracks," - said Jonkers.

Spores of bacteria and nutrients they need added in pellet form to a concrete mixture. But first growth process, these organisms require water. These spores are activated only when rainwater enters the cracks, then this harmless bacterium belonging to the genus of bacilli (Bacillus genus), starts to consume nutrients and produce limestone.

Food for bacteria - is a component of milk called calcium lactate. The microorganisms in the granules quietly tolerate highly alkaline environment of concrete.

"In the laboratory we were able to show that this concrete repairs itself, even when the value of cracks in 0.5 mm, which is three times higher than normal," - said Jonkers. "Now we are expanding. We need to make self-healing agent in large quantities to begin tests in the open air with different designs, different types of concrete, which will test the idea in practice."

At the moment the team is working to reduce the cost of the process. They expect that the improved system will be ready in six months.

Need to conduct surveillance of concrete for at least two years to be convinced of the efficiency of this idea. "After that, if the good results, we can begin the commercialization of the product," - said the researchers.

Even if the reducing agent increases the concrete rates of 50%, this will be only 1-2% of the total cost. The content and maintenance - the lion’s share of the total cost, so scientists expect large savings from the extension of the durability of concrete.

Original: Bbc.co.uk


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