Re-grouting slates for a kitchen - How do i re-grout/cement irregular slate

[Donald]

I have a slate slab floor in my kitchen, laid by someone else, on a sand base and grouted with a sand and cement mix. After three years the floor has settled and there are quite a few cracks and breakages in the cement mix grout. I plan to lift all the sand/cement mix up and to re grout but I want something that is a) pretty permanent and b) flexible enough to cope with any further movement, is that possible?

[lutonlagerlout]

flexible tile grout
LLL

[Donald]

And that despite the size of slabs? Some are 500mm x 1000mm and 100mm thick. Not all are uniform in size either. Still, shouldn't shift too much

[cookiewales]

its a fail take up and relay on solid bed you can use a stone lifter