Eli5 why does wet sand stick together?

Question

Eli5 why does wet sand stick together?

In: Earth Science

Answer 1

Sand particles are quite small, so they have a relatively low volume/mass compared to their surface area (square-cube law). That’s important.

Water undergoes strong cohesive (which is responsible for surface tension) forces with itself due to hydrogen bonds, and it also has strong adhesive (sticking) forces as a result of induced interactions with silicon dioxide – also called wetting. These forces help the light sand particles to stick together, especially when you look at the scale where water is extremely effective for this purpose – as opposed to say ball bearings, pebbles, or golf balls.