How do clays bind?

After a small definition of capillary bridges, let’s what is the macro effect on those glass plate.

So the water (forming capillary bridges), stick the plates together with strength strong enough to withstand several grams in this configuration.
Compared with the clays plate’s grains surface, those glass plate’s surfaces are 100 000 000x smaller.
So with the same surface of clay grains, there are one hundred million times more capillary bridges.
And because the grains are smaller, the strength of a capillary bridge is much more important compared to the grains weigh.
So imagine how strong can be the stick of clays binders!

Fresh clays mortars are sticking enough to withstand a 2-3kg block on a vertical wall.

Same vision at a very smaller scale.