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Scientists turn sand to stone
ScienceNetwork WA   
Wednesday, 06 May 2009
istock_sandcastle.jpg
Research from Murdoch University could
one day turn sandcastles into livable
homes using the new technology.
Image: iStockphoto

Imagine being able to make spray-on roads across the desert, or being able to take a sandcastle home from the beach in the form of a solid rock sculpture. 

These are just two possibilities presented by a new treatment for sand pioneered by Murdoch University’s Dr Ralf Cord-Ruwisch. 

The treatment alters the consistency of sand, doing anything from solidifying it slightly to changing it into a substance as hard as marble. It blends a calcium solution, bacteria and other inexpensive compounds, forcing the bacteria to form carbonate precipitates with the calcium. This creates calcium carbonate, also called calcite, identical to limestone.

“Hopefully it will be civil engineering technology,” says Dr Cord-Ruwisch.

“We can say ‘this sand is too soft’, and then we can make it harder. The soil can be turned from a soft sand into something more like sticky sand, or we can turn it into rock.”

There are many potential applications for this product, says Dr Cord-Ruwisch, with a number of industries already indicating their interest.

“It could be used as a mining application,” he says.

“It doesn't need oxygenation. In theory we could solidify the sea bed before drilling for oil. We could also drill tunnels in the sand, we could make the sand harder so it doesn't cave in.

“Countries like Holland also have shown interest in solidifying their dikes. Dikes would normally be made of rocks, solid stuff, but Holland is a bit like Perth in that they only have sand.

“While dikes made from sand are long lasting, there are certain risks if water intrudes into the dike sand and lubricates the sand particles so they start shifting against each other. Then you can have some instability of the dikes.

“So they really depend on the dikes holding.”

Dr Cord-Ruwisch and his team of researchers have already performed a number of trials with the product, testing the extent to which it can be used.

“The biggest block we have made so far was in a shipping container, just to prove that it can not only work in the laboratory,” he says.

“When we tried to push it in the lab by taking beach sand and treating it many times, maybe ten times, we found that it turns harder each time.

“At the very end, it turned into something resembling marble more than sandstone.

“If you wanted, you could take a piece of Rainbow Beach sand, a beach in Queensland where the wind over time has layered different colours of sand on top of each other, and you could carve a decorative column out of it.

“You could make a sandcastle, set it solid and take it home.”


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