[m4rtink]

Interesting! But what holds these blocks at the separation once the foam is no longer load bearing ? Some external bracing ?

[londons_explore]

Typically the foam is only in the middle of the concrete slab, so there are still a few inches of attachment all around all the edges with contact. There is rebar in those edges too.

[m4rtink]

Interesting, do that's how it works - thanks for the explanation! :)