With concrete being one of the most used materials in the world from buildings to roads, it doesn’t matter how careful you are when mixing it, or how much you reinforce it, cracking has always been a problem with no fix in sight, until now, that is.
In the Netherlands, Professor Henk Jonkers from the Delft University of Technology explained to CNN: “The problem with cracks in concrete is leakage. If you have cracks, water comes through—in your basements, in a parking garage. Secondly, if this water gets to the steel reinforcements—in concrete we have all these steel re-bars; if they corrode, the structure collapses.”
Hendrik Marius Jonkers—Self-healing concrete containing bacteria:
Jonkers, who is a microbiologist, and his team have come up with an entirely new way of combating the problems.
“We have invented bio-concrete; that’s concrete that heals itself using bacteria,” he says.
The bio-concrete is mixed much the same as regular concrete, with one extra ingredient—the “healing agent.” This agent dissolves and becomes active after the concrete sets, and only if the concrete cracks and water gets in.
It wasn’t until in 2006 after a concrete technologist asked Jonkers if there was a possibility to use bacteria to make a self-healing concrete did he begin to work on the idea. It took him three years to solve the problem.
“You need bacteria that can survive the harsh environment of concrete,” says Jonkers. “It’s a rock-like, stone-like material, very dry.”
Self-healing concrete with the use of bacteria, with Dr Erik Schlangen from the Delft University of Technology:
Because concrete is very alkaline, Jonkers chose the bacillus bacteria for the job. This is because they thrive in alkaline conditions and produce spores that can survive for decades without food or oxygen.
“The next challenge was not only to have the bacteria active in concrete, but also to make them produce repair material for the concrete—and that is limestone,” Jonkers explains.
Dutch scientists create “self healing” concrete:
For the bacilli to produce limestone, it needs a food source. Jonkers looked at sugar, but this would have just made the concrete soft and weak. In the end, Jonkers chose calcium lactate, setting the bacteria and calcium lactate into capsules made from biodegradable plastic, and adding the capsules to the wet concrete mix. The bacteria then germinate, multiply, and feed on the lactate, and in doing so they combine the calcium with carbonate ions to form calcite, or limestone, which closes up the cracks, said CNN.
Jonkers has hopes that his concrete will be the start of a new age of biological buildings.
I’m not totally convinced yet; concrete has been tested over many years, and is still being tested today. Maybe in a few years of being tested I may change my mind on using it for buildings.