Cut down aerated concrete wall, now it looks like hell

[firefly]

Hello!
I hope this is the right part of the forum.

I cut down a lightweight concrete wall in the hallway where a doorway used to be to create a bit more open space.
The problem is that it became very uneven, and on one side a lightweight concrete block fell out. What is the easiest way to attach this?



On the other side, it looked easier until I noticed that the walls before/after the section I removed are different. About a 1.5 cm height difference. Chisel out the mortar that protrudes and try to make a smooth transition with filler? Alternatively, plasterboard?
I'm a novice at this, so all opinions are appreciated.

 

[Plutus]

Avoid putting it back, fill with expanding foam. and as you said, smooth out and spackle.

 

[Exostor]

Expanding foam is likely to burst the wall piece on the right that is still intact. Instead, fill it in with joint compound or C-bruk.

 

[Nerre]

Gypsum plaster is very nice to work with, I noticed when I patched cracks in the basement's lightweight concrete wall.

 

[Direktörpelle]

Plaster! The downside is the drying time

 

[MaZtoR]

I also cast my vote for gipsbruk. Gypsum can be applied in thicknesses between 2-60mm per batch without reinforcement. Absolutely wonderful to work with.

 

[firefly]

Thanks a lot for the tips I assume the plaster is sandable? I bought a chisel to clean out the "groove" shown in picture 2. But it wasn't very effective. Feels like a jackhammer is a bit overkill..?

 

[Claesk]

Can't you embed a plasterboard? That way it becomes smooth immediately. It can be difficult to spackle evenly.

 

[ByggaNytt]

Gypsum filler is not directly sandable but works excellently for filling and can then be topped with a more easily sandable sand filler!