Scientists discover why sandcastles are really child's play
London (PTI): Building sandcastles is a child's play, every beach goer knows. You just add water.
Yes, a joint team of German and Australian researchers in Germany has discovered that water is the secret behind firm sandcastles. They've revealed the way water glues sand grains together what they call a grain-liquid-air interface.
Scientists have previously claimed that the formula for the perfect sandcastle is eight parts sand to one part of water. But, this study has shown that almost any ratio is capable of achieving a sandcastle any child could be proud of.
"You don't need a recipe to build a sandcastle. Properly dry sand doesn't stick together at all. But, any kind of wet sand, from fairly wet to very wet, or in fact relatively dry, behaves almost the same way," according to Dr Adrian Sheppard of the Australian National University.
Dr Sheppard and his fellow researchers, led by Prof Stephan Herminghaus at the Max Planck Institute for Dynamics and Self-Organisation in Germany, used a bright source of X-rays -- generated by a device called synchrotron -- to probe wet sand at a microscopic level.
The strength of a sandcastle depends on how the grains interact, rather than the amount of water. According to them, the results reveal that water forms into a flexible variety of microscopic bridges and clusters holding the sand together.
"The remarkable insensitivity of the mechanical properties to the liquid content is due to the particular organisation of the liquid," the British media quoted Prof Herminghaus as saying.
The team also found that this was true whether the grains were perfect spheres or, more realistically, all uneven -- the results have been published in the latest edition of the 'Nature Materials' journal.
Sci. & Tech.