Unusual material under floor, somewhat like pumice stone or sponge...

[hdad]

What could this be?
It's under the floor along with sawdust. When you step on it, it turns to powder.

 

[skutten11]

Some slag product with a lot of air in it, people used whatever was available to insulate in the past, maybe from a blast furnace or so, do you have any idea if there has been anything like that in the area?

 

[banjoragge]

Lightweight concrete crusher. Check out this thread https://www.byggahus.se/forum/threads/taeta-mellan-platta-och-syll-foer-ventilerat-golv.299233/

 

[Stickan56]

It is pumice stone. In old houses, you can find peat, straw, coal dust, etc. in the floor structures.

Stickan

 

[Gunnar_A]

When my father built a villa in the early 1950s, this was used as insulation under the basement floor slab, between the ground and the floor so to speak. It was then called slag, but I don't know what kind of slag. I remember it smelled a bit like poop.

 

[raveper]

When we were small, we used to draw on asphalt with similar material. I thought it was pumice. The other day it struck me that the blue variant must have been blåbetong...

 

[BirgitS]

Here are many pictures of pumice: https://commons.wikimedia.org/wiki/Category:Pumice and I don't think it's very similar to TS:bild.

 

[Nils82]

Granulate. A slag product that was a very common insulation material in the past. Used in both houses and apartments. I can imagine that it was very cheap and easy to handle.

 

[Wikstroem]

I think it looks like perlite. Used, albeit to a limited extent, as an insulating material in houses both in the past and now.

 

[irihenke]

What could this be?
It is under the floor together with sawdust. If you step on it, it turns into powder.

Are you going to tear up a lot of floors?
A bit curious about the condition. Moisture stains?
A bit embarrassing to admit, but I've never seen it in any construction before.
A lot of other insulation, but not this one.

 

[Stickan56]

Granulate. A byproduct that was a very common insulation material in the past. Used in both houses and apartments. I can imagine it was very cheap and easy to handle.

What do you mean granulate. It only tells about the form of the material, not what substance it consists of.

 

[Nils82]

What do you mean granulat. That only tells us the shape of the material, not what substance it consists of.

Sure, sure.....remove the word granulat in my post if that feels better.

 

[hdad]

are you going to tear up a lot of flooring?
a little curious about the condition. moisture stains?
a bit embarrassing to admit but haven't seen it in any construction before.
lots of other insulation but not this one

The floor that has been torn up is about 25sqm, framed on concrete above a basement. No moisture or anything else.

 

[En glad jävel]

Around Västerås, it is a very common material in floor constructions from the 40s and 50s. It is a by-product from the industry, in Västerås from Metallverken, called granulated blast furnace slag or simply "granulation." I am not aware of it being dangerous in any way, but given its origin, wearing a respirator is recommended if you are going to shovel it around. If it becomes moist, it is aggressive towards metal (pipes).
/Jävel