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Self-healing Concrete using Bacteria to prevent ingress of water.

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  • havewala
    Self-healing Concrete using Bacteria to prevent ingress of water.
    Message 1 of 1 , Jun 4, 2013
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      Self-healing Concrete using Bacteria to prevent ingress of water.

      http://www.bath.ac.uk/news/2013/05/30/micro-capsules-and-bacteria-to-be-used-in-self-healing-concrete/

      Micro-capsules and bacteria to be used in self-healing concrete

      30 May 2013

      A new research project involving researchers from Bath aims to develop
      novel self-healing concrete that uses an inbuilt immune system to
      close its own wounds and prevent deterioration.

      The life of concrete structures is reduced when the material cracks
      and water is able to get at the steel reinforcement, causing rust and
      degradation.

      The project is funded by a £2m EPSRC grant, matched by an additional
      industrial contribution of just over £1 million, and will involve our
      researchers in collaboration with Cardiff University (the lead
      partner) and the University of Cambridge.

      Our team here at Bath aims to develop a concrete mix that contains
      bacteria within microcapsules, which will germinate when water enters
      a crack in the concrete to produce limestone (calcite), plugging the
      crack before water and oxygen has a chance to corrode the steel
      reinforcement.

      Self-healing concrete could vastly increase the life of concrete
      structures, and would remove the need for repairs, reducing the
      lifetime cost of a structure by up to 50 per cent.

      Over seven per cent of the world’s CO2 emissions are caused by cement
      production, so reducing the amount required by extending the lifetime
      of structures and removing the need for repairs will have a
      significant environmental impact.

      Dr Richard Cooper, from the Department of Biology & Biochemistry,
      said: “Cement is highly alkaline, making it a hostile environment for
      bacteria. We’ll be assessing different species of bacteria to find one
      that is able to form abundant spores and which will survive and
      germinate in this environment. The work will involve finding
      alkaline-tolerant isolates and testing their biology and physiology.”

      Dr Kevin Paine, from the Department of Architecture & Civil
      Engineering, said: “Concrete densifies as it hardens, so the pore size
      decreases to a level where bacteria may be crushed. We’re looking at
      enclosing the bacteria in micro-capsules, along with nutrients and
      calcium lactate which the bacteria will convert when water becomes
      present and use to fill cracks in the concrete.”

      Dr Andrew Heath, also from the Department of Architecture & Civil
      Engineering, said: “Self-healing materials are particularly suited to
      situations where safe access for maintenance is costly, so the outputs
      of this extended research programme could reduce the life-cycle costs
      of infrastructure.”

      Dr Cooper added: “Including bacteria in concrete offers a double layer
      of protection in preventing steel corrosion. Not only do the bacteria
      work to plug cracks in the concrete, the process of doing so uses
      oxygen present which would otherwise be involved in the corrosion
      process of the steel bars.”

      The research team will assess the survival of different species of
      bacteria in the concrete over time. They’ll allow the concrete to
      mature over certain time periods and then grind it down to create a
      suspension which can be assessed by biologists for surviving bacteria.
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