Hi, I would like to know what mortar to use for a part of a wall where I want to place bottle bottoms (2 united backgrounds each other) as bricks. As the glass does not expand, I would like to know if I should avoid putting lime, and if I should add some type of hydrophobic to the water of the mixture, thanks The photo is an example of what I would like to do

And you put the mixture hydrophobic to avoid water ingress in the interior of the wall.