Reply With QuoteThis so needs to be nominated for an IgNobel.
Then again, this does has potential relevance in terms of concrete production.
Cool find.
How to construct the perfect sandcastle
Maryam Pakpour, Mehdi Habibi, Peder Møller & Daniel Bonn
Scientific Reports 2, Article number: 549 doi:10.1038/srep00549
Received 11 June 2012
Accepted 17 July 2012
Published 02 August 2012
Just a bit of water enables one to turn a pile of dry sand into a spectacular sandcastle. Too much water however will destabilize the material, as is seen in landslides.
Here we investigated the stability of wet sand columns to account for the maximum height of sandcastles. We find that the columns become unstable to elastic buckling under their own weight.
This allows to account for the maximum height of the sand column; it is found to increase as the 2/3 power of the base radius of the column.
Measuring the elastic modulus of the wet sand, we find that the optimum strength is achieved at a very low liquid volume fraction of about 1%.
Knowing the modulus we can quantitatively account for the measured sandcastle heights.
Introduction
The formation of capillary bridges between sand grains are the cause of the stiffness of sculptured wet sand in a sandcastle, as opposed to dry sand which can hardly or not support its own weight.
Qualitatively, the liquid leads to the formation of capillary bridges between the sand grains, and the curvature of the liquid interface leads to a capillary pressure causing a force of attraction between the grains. This then creates a network of grains connected by pendular bridges, and allows, for example, creating complex structures such as sandcastles.
Not many quantitative studies on the mechanical properties of wet sand exist, in spite of the fact that the handling and flow of granular materials is responsible for roughly 10% of the world energy consumption.
Since in many cases the humidity in the air is sufficient for liquid bridges to form between sand grains, one would expect the mechanical behavior to be well known.
This is not the case, in spite of the fact that the stability of wet granular packings is of paramount importance for civil engineering purposes and that the adhesive forces due to the presence of liquid bridges are also extremely important in geophysical applications (i.e., soil stability), of which sandcastles are merely an unusual example.
More: http://www.nature.com/srep/2012/1208...srep00549.html
Creative Commons Attribution-Noncommercial-ShareAlike 3.0 Licence
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareALike 3.0 Unported License.
To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/
Last edited by Lt-Col A. Tack; 08-04-2012 at 11:50 PM.
This so needs to be nominated for an IgNobel.
Then again, this does has potential relevance in terms of concrete production.
Cool find.
This will come in handy.
The object of the first post is to provide background information on the activity that so many kids now enjoy thoughtlessly.
It's no longer acceptable to just enjoy building stuff out of wet sand.
Last edited by Lt-Col A. Tack; 08-05-2012 at 02:54 PM.
Why would it need to be nominated for an IgNobel?Originally Posted by IraGlacialis
Because it is one of those studies that would, upon first glance, make people screech about useless research grants and such. "Because what purpose does studying sandcastles help with starving Africans?"
That, and IgNobels aren't just awarded to "useless" projects but are also awarded to things that are just plain unique and/or awesome (eg: the peace prize for the mayor who runs over parking violators with a tank).
Well no point using dry sand it's not going to hold is it duhhhhhhhhhhh .. everytime when i made a sand castle when i went to the beach when i young .. always used the wet sand .. held every time ..
christ you don't need a scientific mind to figure that out ffs ..
Your point is duly noted Ira
Posting Permissions
