Everyone knows the secret to building sandcastles is a little water. But while too little leaves the sand useless, too much makes it heavy enough to cause disastrous landslides. Fortunately, scientists have unravelled the secrets behind sandcastle building for you.
While it might sound flippant, building the best structures out of sand is a tricky civil engineering problem. That’s why a team of scientists set to a complex series of experiments involving theoretical and practical modelling of sand castles.
By testing different levels of sand wetness, they studied how columns of sand buckled as they were built higher and higher. Eventually, they found that there’s an optimum sand wetness: you should be aiming to have a liquid volume fraction of 1 per cent. That means that, by volume, you need to combine 99 parts of perfectly dry sand with 1 part water to build the ultimate castle. Learn more here or here.