What keeps sandcastles standing?

  title={What keeps sandcastles standing?},
  author={Daniel Hornbaker and R{\'e}ka Albert and Istvan Albert and A. L. Barab{\'a}si and Peter Schiffer},
Any child playing on the beach knows that the physical properties of wet and dry sand are very different. Wet sand can be used to build sharp-featured sandcastles that would be unstable in dry sand. We have now quantified the effect of adding small quantities of liquid to a granular medium. Nanometre-scale layers of liquid on millimetre-scale grains dramatically increase the repose angle (the steepest stable slope that the substance can form) and allow the development of long-range correlations… CONTINUE READING