Possibly one of many press reports in 2012 of paper by Dutch physicists
in Nature's Scientific Reports. Synopsis:

"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."

http://www.nature.com/srep/2012/1208...srep00549.html

I remember discussing at the time the possibility of a bid for EU
funding to establish a consistent set of measurements and ratings for
beaches across all member States. But we concluded the German's would
be bound to get there first

--
Robin
reply to address is (meant to be) valid