Identifying material on masonry wall

[phloaw]

The inner side of an exterior wall in my house has, behind the plasterboard, a kind of masonry which I'd like to identify.
I attach pictures.
It looks like concrete but it's quite easy to drill: I can very easily drill it with a 2mm wood/metal drill bit in a HAND (i.e., not electric) drill.
This material is at least 5cm thick (maybe more), as inferred from the hole I drilled.
So, what's the name of that substance? Is it safe to hang heavy stuff (e.g., a radiator) to it using rawlplugs?

Thanks!

[tonyshouse]

Looks like an aerated concrete block, I hate them. Easy to drill and fix to 5.5 hole not on hammer red plug no10 (4mm) screw 50mm ok for rad, dont overtighten 

[phloaw]

18 minutes ago, tonyshouse said:

Looks like an aerated concrete block, I hate them. Easy to drill and fix to 5.5 hole not on hammer red plug no10 (4mm) screw 50mm ok for rad, dont overtighten 

Thank you! I was also fearing Thermalite, but wanted additional opinions.

I've seen there are special plugs for Thermalite, as opposed to normal rawlplugs: would you recommend them?

PS: the total radiator weight should be between 30 and 40kg.

 

[markc]

Although a rad can be heavy, its mass is close to the wall and the fixings are predominantly in shear. Had you been fixing shelf brackets that put the fixings more in tension then things can get messy ... and broken when they hit the floor.

P.S. tall `designer` rads look like climbing frames to kids and this becomes a whole different story for fixings.

[ToughButterCup]

8 minutes ago, markc said:

...

P.S. tall `designer` rads look like climbing frames to kids and this becomes a whole different story for fixings.

 

A Post Scriptum can sometimes become essential knowledge. Thanks ?