Eli5 why does wet sand stick together?

Question

Eli5 why does wet sand stick together?

In: Earth Science

Answer 1

Damp sand sticks together because water forms little grain-to-grain bridges. Surface tension–the same force that lets some insects walk on the surface of a pond–acts like rubberbands between the grains. Adding water to damp sand fills spaces between the grains. The bridges vanish and the sand begins to flow more easily.