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Dutch develop self-healing bio-concrete

Dutch researchers have invented a biological concrete that can seal its own cracks, preventing water ingress and corrosion of reinforcement.

The technique uses a special strain of mineral-eating bacterium that can tolerate high alkaline environments such as those found in concrete. Millions of dormant bacteria are incorporated in the aggregate during concrete production along with packets of chemical “feed”.

If the concrete is cracked and oxygen and water are introduced, the bacteria become activated. The bacteria then convert the feed into calcite, which seals the crack. Once plugged the bacteria return to their dormant state.

Delft University of Technology in Holland has successfully trialled the concrete and is working to make it commercially viable. The bacteria and feed currently costs €80 (£78) per cubic metre, roughly doubling the price of per cubic metre of concrete.

The work has been led by research scientist Henk Jonkers. He said the cost of the bacteria is small in terms of overall construction costs, but is still keen to make it more competitive.

He is working with industry partners to cut the cost of the bacteria and feed mix to £17/m3. If costs can be brought down, Jonkers believes the technique will first be used in tunnel lining segments.

“It took me over a year to come up with the right combination that would not adversely affect the concrete properties.”

Henk Jonkers

“It’s difficult to persuade industry to invest in the upfront cost,” said Jonkers. “We hope to have something suitable on the market within two years for the tunnel sealant and are developing ways to reduce the cost to about £17/m3,” he added.

Jonkers and his team has spent four years perfecting the technique. “It took me over a year to come up with the right combination that would not adversely affect the concrete properties, then another three years of testing,” he said.

“The new concrete would be perfect for structures which are difficult to maintain, like underground buildings, motorways or oil rigs,” said Jonkers.

“It is extremely durable. The bacteria are specially adapted to extremely alkaline environments, and can survive dormant inside the concrete for up to 50 years.”

Readers' comments (6)

  • This sounds great. No more cracks in the dykes.

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  • How does this compare with Xypex that I understand provides a self healing ability by the formation of non-soluable crystals?

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  • Sounds like a good thing. I hope it is taken further & hope to see this form of autogenesis in use on appropriate structures.

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  • This sounds like a great alternative to the 75mm plus cover to reinforcement that we now need to incorporate in our highway structures. However, it assumes that the bactieria which love high alkalinity can cope with de-icing salts and/or carbonation. Can they survive in other aggresive environents too?

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  • Simon Dunn

    Its great to see self healing concrete get a mention in NCE. Having been working on self healing materials here in the UK (Cardiff University) for 3 years, the issue of cost is one which does plague such a concept. However, when you take into account the "Life Cost" of a structure constructed using such a material they do become more attractive. With reduced maintenance, longer life and less material required (reduced cover for example) the life cost of a self healing concrete is very likely to be less than traditional concrete, however the problem lies in convincing clients and engineers to outlay a larger initial cost for a long term gain. Furthermore self healing concretes not only have improved economic sustainability but also improved environmental sustainability (reduced material, better durability etc) and social sustainability (reduced congestion/loss of use of structure due to maintenance etc). So self healing concrete seems to tick all the boxes for sustainability and application but why is it that such projects in the UK struggle to find research money?

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  • Sounds good on the face of it however what impact does the Bacteria have on Health & Safety. Some people are allergic to certain strains. Also I agree that there will be an uphill battle to get more spent for long term gain as we find when offering better quality coatings to the industry. The opposition is that short term cost savings matter now and short sitedness is a big issue.

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