bathroom floor tiles coming loose

[uzairfarooqi]

Hi everyone, I saw a couple of similar posts on this but since my situation is somewhat unique I figured I should start a new thread. I'll keep it short but let me know if you need me to provide any additional information. My girlfriend uses an electric wheelchair. For a few months now the grout around the tiles, in the area of the bathroom she drives in to use the sink, has been breaking off. Some of the chipped pieces have slid under the tiles which cause the tiles to also wobble if you stand on the edges and its only getting worse. Any advice on how I could fix this and what I should be using so the problem doesn't just come back later on? As you may be able to tell I'm not much of a DIY man so a "tiles for dummies" language would be most welcome
Here are some pictures of the tiles: https://www.dropbox.com/sh/pfkf6zj5xuy27rf/tsqaq1ZQfN?m
Any help would be greatly appreciated.
Thank you.

 

[Rookery]

Its almost certainly caused by movement and/or inadequate fixing. The only lasting solution is to take the tiles up and start again.

 

[Del W]

More than likely theres movement(up and down) in the floor.Maybe the tiles were not fixed properly or the floor that the tiles are fixed to is not supported enough.

 

[Ajax123]

What are the tiles stuck to and with what were they stuck??

 

[kilty55]

definately lift the tiles and find what the substrate is for starters then re assess and re tile if suitable

 

[uzairfarooqi]

I see. Yes I figured I would probably need to take them out and do it over because they're in pretty bad shape by now. In that case could you advise me on what product to use around the tiles to fix them in place? (I had looked at a liquid cement crack filler earlier but I'm not sure if its cement that's used for this.) Also would I need to apply something underneath the tiles?

@Ajax123 The floor beneath is concrete, or at least it appears to be to me. I'll attach a picture of the floor and the underside of the tile in case that helps. If you meant to ask what was used around the tiles to stick them in place, I don't know unfortunately. I did not have them done myself.

https://www.dropbox.com/s/8izupxma6ilhcjt/2012-07-21 14.35.50.jpg?m
https://www.dropbox.com/s/roga9qklvb9n1un/2012-07-21 14.36.40.jpg?m

 

[White Room]

Was the tile that came up have any adhesive on the back of it.....

 

[Qwerty]

Looks to me that the adhesive bond has failed......or the wrong adhesive or prep (not primed) used. How many more have failed or sound hollow?

 

[uzairfarooqi]

There's three of them that can easily be lifted off. Its the ones that see action when she turns her chair towards the sink. If the black substance at the back of the tile, which felt almost rubbery, was the failed adhesive then yes adhesive had been used. Once again I'll stress my ignorance in DIY but I'm sure it comes off naturally in my description

So am I far off in guessing I'll need to remove the previous adhesive off the back of the tile, apply new one, clear the floor, replace tile and fill the edges with..something?

 

[AliGage]

Have a scrape at the floor and see if there's any gluey residue. I would hazard a guess from your pictures that the floor used to have lino or vinyl glued down. When the tiles were "fixed" the glue rewsidue wasn't removed. The adhesive is still all stuck to the back of the tile from your pictures. So something's there that is stopping the adhesive bonding to the concrete. The back of the tile, showing the adhesive, looks free from dust and particles from the floor. So yeah, i'd put my money on glue being on the floor.

Tiles need to come up. Floor needs cleaning. You should be able to scrape it up with a blade. Any stubborn bits get a heat gun or blow torch on it.
Prime the floor with SBR (not PVA) and re-tile with a good, single part adhesive.
I would look into fitting a de-coupling membrane to be on the safe side.