I'm trying to make floor tiles which should look similar to attached picture. I sliced a wood about 6mm thick and wanted to glue them to the mdf base. However when I put PVA glue on a wood slices, they bent. Corners of slices raised from a base from 3 to 7 mm. Bending is really huge and caused by the moisture of glue. So with such a deformation gluing is not possible at all. I tried to straighten slices with a board on top of them and clamps but only crack a couple of them.
So the question is how to prevent wood bending? or is there other way to attach slices to a base?
PS: as mentioned in comments, each tile is supposed to be a rectangular about 800x400mm, these sizes could vary. Slices (open grain pieces) are going to have width about 60-85mm (85 is the capability of a saw) and length 60-100mm.