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Scientific News
Scientific News    Biology    Biotechnologies AUSSIE BIO-CEMENT TO SAVE DUTCH DYKES


Bio-cement in action: Grains of sand, some of which are being bridged together by microbially produced limestone crystals.An Australian researcher is using bacteria to develop a biological cement that may help patch up failing Dutch dykes, essential in protecting the land from rising sea levels.

Vicky Whiffin of
Murdoch University has been experimenting with bacteria which convert sand into sandstone, as part of her PhD research.

"With this technology, it is possible to cement material 'in-situ'," said Ms Whiffin, adding that she hopes the bio-cement will be useful in the restoration of historic buildings, mine-shafts, and other industrial structures as well as dykes.

The bacteria produce an enzyme called urease, which converts urea into ammonium ions and carbonate.

Whiffin has found that when a particular concentration of calcium is added to the reaction, calcium carbonate (limestone) is formed.

In the presence of sand, the limestone binds the sand together to form a sandstone "cement".

"All the inputs are liquid so they can be easily injected into or sprayed onto a structure that needs cementing," she said. Three applications of the bio-cement are used and each takes a day to set.

"We've already done some small scale laboratory studies, and we hope to do some pilot scale field trials in The Netherlands," she said.

Ms Whiffin found the bacteria were very useful in cementing sand samples from dykes and a Dutch company called Geodelft is now interested in raising funds for field work.

She said that one problem with using regular cement is that it is not porous and this means it does not remain structurally stable.

By controlling the amount of calcium and sand added, Ms Whiffin has been able to control the strength and porosity of the final. She can even add sand of different colours for aesthetic fit.

Overseas companies are testing the use of bio-cement in the bioremediation of waste such as disposing of strontium produced by nuclear power plants.

The bio-cement is being sprayed onto the waste to bind it and prevent it spreading into groundwater.

Ms Whiffin is supervised and funded under a joint arrangement involving Murdoch University and a company called Lithic Technology.

Source of the given news and the copyrights belong to a ABC Online News

Publishing date: June 18, 2002



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