Interior wall in concrete house - lightweight concrete or "real" concrete?

[tacho]

Just tore out one of the door frames in our apartment built in 1950. Now I'm wondering which screw to use to attach the frame sleeves to the new frame and the choice is between concrete screws and light concrete screws (i.e. the types that don't need plugs). Attaching pictures of how the wall looks.

To an untrained eye, this looks like some form of masonry blocks, and even a brick seems to be peeking out. What do you think?

 

[Matti_75]

It looks like aerated concrete. Try sticking the knife in; if it goes in, it's aerated concrete.

 

[tacho]

Did a test by chopping a bit with a Morakniv. Even when I put in quite an effort, the tip only goes in a few millimeters. Could it really be concrete after all? Did/Do they make blocks out of anything other than aerated concrete?

 

[Stefan N]

Some form of concrete block it is, maybe prefab-block.

 

[tacho]

And thus should I not choose lättbetongskruvarna?

 

[MathiasS]

nah, regular nylon plug will be fine.

 

[tacho]

I was thinking of testing the type of screw that only requires drilling, looks like this:





There is also a variant for lättbetong, but I'm not choosing that one.

 

[MathiasS]

If you start by drilling into the block, you'll see what material it is...

 

[tacho]

Follow-up;

The walls were pretty hard concrete, definitely not lightweight concrete. However, no match for the hammer drill

I ended up using plugs and regular screws instead. Partly because I suspect the concrete screws put a lot of force on the wall (risk of cracking) and also because the ability to dismantle and adjust the frame is greater with plugs.

The result: