How to handle natural stone slabs for a terrace?

Hi, a question for the pros, we had a terrace made of travertine by a company, they laid the slabs (30x60cm) in gravel. Do they now still have to be swept in with quartz sand and then vibrated again? Our terrace builder said it's not necessary, besides he doesn't have a roller vibrator for such slabs anyway.

Best regards & thanks

Terrace slabs are not vibrated, they break that way. And for the joints, crushed sand/gravel is used, not quartz sand (even though many do it that way).

Thank you, I had read that there is a special roller vibrator for that, the problem for me is that after almost a year, some slabs have settled quite a bit by 3 - 5mm.

That is the disadvantage of installation in gravel and almost unavoidable.

That is the disadvantage of installation in split and almost unavoidable.

I knew that, but not that extreme and so much, but the terrace builder has to fix that, right? It's not even a year old yet.

And for the joints, you use crushed sand/gravel, not quartz sand (even though many do it that way).

Our garden and landscaping contractor said that the fine gravel wedges itself into the joints, reduces wobbling, and only then gives stability to the surface. And make sure to sweep again nicely, about 3-5 times, at intervals of 4 weeks.