Tiles Lifting, concrete floor with asphalt

[Dawz84]

I'm having an issue with my kitchen tiles a few years after installation. The house is 1950s and, like many at the time has a concrete floor with asphalt top layer that is 2 to 3cm thick. Acts to stop rising damp and levels the concrete.

When my kitchen was fitted they created channels in the floor for electrics, drainage, water etc. They infilled these with some sort of compound. It looks like a concrete mix; I remember it dried fast (hours). They laid tiles over this, and what I've noticed is the floor is lifting in area's these channels are (not everywhere) and, in some cases, where this "concrete" has been poured. It was also used to fill holes where the old internal walls were that we had removed.

Now on inspection, what I think is happening is the Asphalt has a different rate of expansion (or possibly reacting with the concrete) and where its against these channels its got no where to go and thus lifts the tiles.

The obvious solution in my mind is to chase a gap for expansion around the channels, then use some sort of flexible waterproof screed/adhesive to put the tiles back down. Or do I fill the expansion gap with a bit of cork/foam board?

I could be wrong; maybe the concrete mixture simply wasn't primed? causing some delamination issues in these areas? Perhaps a mixture of both?

Thanks for the help.

[dewaltdisney]

It is probably self leveling compound, a quick drying cement based mix often used as a tiling base for floors. I don't like pipes and wires buried and I would be looking at a solution to replace the floor in a way to give access. Whether thiis would be to reroute the services to the edge or to have a vinyl floor on ply you can pull up if necessary. Just my view.

DWD