I have a big hole in my kitchen floor (inserting a beam and post to take down a load bearing wall), and I'm now left with having to fill this hole (after dumping around 300 mm of concrete on the post footing).
It's a floating concrete floor and the hole is right between two of the concrete beams (500 mm apart). On each beam there is a small (20 mm) lip. The floor is beam and block (except instead of blocks it's just polystyrene insulation blocks) with the concrete poured on top.
I've heard two suggestions on how to fix the hole:
1) Cut the edges of the hole clean, then cut and put a 40/50 mm thick concrete slab (council slab) on the lip, DPM, celotex insulation 100/80mm, another DPS sheet, and then 40-50 mm of concrete (with mesh) on top.
2) There is about 400 mm of air between the ground and the bottom of the floor. dump hardcore in the hole until it's level with the floor, then basically just add a bunch of concrete and the 100 mm insulation.
I'm putting laminate flooring (so I'm doing a DMP paint, and then adding plastic DMP sheeting) and would like to not have to wait forever for a very thick layer of concrete to dry out (which could take months), as we are eager to start working on making the room habitable.
I'm a bit worried that the 20 mm lip supporting the concrete slab (Option 1) will cause a very high load along the middle of the slab, which might cause it to snap like a KitKat. Maybe adding the hardcore (Option 2) would be a good idea to support the slab? or having a steel plate cut?
Any suggestions or comments will be appreciated.