Factorio Forums

If you place quality concrete or refined concrete (and I assume similar with stone bricks) and then pick them up again (mining) they come back as normal quality. This doesn't seem like it should be the intended behavior though I can understand that from the perspective of the game once it's laid down there isn't a practical difference.

If this IS the intended behavior maybe due to an engine limitation, like the game just can't keep track of quality tiles, then I would suggest just not allowing them to be placed on the ground, since if you have rare concrete there's no reason to be placing that as a tile.

As far as I can tell this happens every time, very repeatable.

This is not a bug. The tips & tricks about "Quality" actually say that this is intended behavior:

Quality improves certain aspects of entities, items and equipment.
[…]
Items that can be used as buildable tiles can benefit from quality only as a part of other recipes. They revert to normal quality upon being placed as tiles.