Evil black stuff

[AMc]

I'm currently pulling up a floor laid over the brick/pamments/pamments in the old kitchen. The pamments are coming up for a clean before insulation and underfloor heating goes in and they get relaid.

I originally thought it was concrete but as I've removed filthy, grey sections to get to undisturbed ones I've discovered it's red gunk with some shiny stone embedded in it. It seems to be stuck/sealed to the pamments below with smelly black tar/bitumen.

Quick questions -
What the hell is the red gunk?
What's the quickest/cleanest/greenest way to clean the pamments ready for reuse?

 

[Nemesis]

Terrazzo? On a screed?

http://www.premfloor.co.uk/terrazzo-floors.html

 

[chuckey]

The red stuff I think is latex reinforced cement. I had this laid on top of limestone flags, when a chisel was inserted in the joint between it and a flag, the whole room size sheet lifted and was flexible. 99% of it came away cleanly from the flags. its a crude form of DPC.
Frank

 

[AMc]

I thought that Terrazzo was a (very) modern & (very) expensive material and this is in a 1950's/60's conversion in a farm house with PVC tiles stuck to it?

Latex reinforced concrete is new to me - its certainly coming up easily in quite large chunks and seems quite light and flexible. It was mainly the bright red colour that surprised me.

I just need to know what to use to remove the evil black gunk left behind. Something to remove tar used before I lift them or lift them and clean them with a pressure washer afterwards perhaps?

All contributions gratefully received etc.

 

[Nemesis]

No, terrazzo isn't that modern - but it wasn't clear to me that these are plastic tiles, they look like terrazzo, (although on second look too thin) so presumably are made to look like that. Here's a bit of history:

http://www.tricontracting.co.uk/index.php?content=products&area=terazzo-history

Whatever the red stuff, it's presumably sonme sort of levelling screed, although the embedded stones are a mystery and its composition could be anything, (ours seemed to be sawdust mixed with some agent to bind it) as long as it's coming up OK I wouldn't worry. Hopefully no asbestos but...

Have a look on the tilessoc site for ways to clean unglazed ceramic flooring, and ask Strippers about products to remove bitumen.

 

[AMc]

Hopefully no asbestos but...

Definitely no asbestos as a £600 survey showed Asbestos reinforced water tank and asbestos reinforced bath panels are the only things I need to worry about.

Thanks for the terrazzo link

 

[Nemesis]

I meant in the flooring mix. But it's unlikely.

 

[PC]

Looks like a Magnesite floor screed.

Thin screed, Red in colour.

PC

 

[Nemesis]

Interesting! Thanks PC.

http://www.enigmatist.com/free/john49/tbsfaq.htm

Magnesite is only likely in old houses (pre about 1920) on ground floors. Normally coloured coral pink or verdigris. A small lump, when held in a gas flame will glow brightly, like a gas mantle, at the edges.

The dates may be out of kilter though.


Magnesite (Magnesium Oxychloride) Flooring

Magnesite flooring is not commonly used at the current time but was very popular for domestic applications in the period 1920 to 1940, and for Local Authority housing between 1945 and 1960. It is usually a reddish pink colour although some floors were coloured using pigments. It was commonly applied on top of concrete ground floor slabs. Magnesite flooring was made from a mixture of calcined magnesite and magnesium chloride solution with various fillers (e.g. wood flour, sawdust, asbestos). It was typically laid between 10 and 25mm thick, but two coat applications could be up to 50mm thick. Magnesite floorings are very vulnerable to dampness and if there is any doubt about moisture protection, it should be replaced. Chlorides may migrate from the magnesite into the concrete below and corrode any reinforcement or gas and water pipes. Most magnesite floors are now coming to the end of their life, only if they can be guaranteed to remain unaffected by moisture can they be used as a screed to receive other floorings, otherwise the flooring should be replaced.

Identification: It is easy to confuse magnesite with a pigmented sand/cement screed; however the following features can aid identification. Magnesite flooring is electrically conductive and so an electrical resistance moisture meter will give a full scale damp reading even when the material is bone dry. Also, a small lump when held in gas flame will glow brightly, like a gas mantle at the edges.

Further reading: PYE, PW and HARRISON, HW. Floors and Flooring, BRE, 2003.

The information contained in this nugget has been provided by The Concrete Society technical staff.


Wonder what ours was. Yellow. But looked as though it contained sawdust. The asbestos suggestion is worrying, and did occur to me when we chipped away at it, but mostly we have dug it up now. Laid on top of stone flags.

 

[AMc]

I'll get my multimeter on a chunk later on!

Interesting - suggests that part of the previous renovation is older than we thought. It's all coming up anyway. Thanks again!

 

[PC]

Thanks Nemesis

I do have my use's but dont guarantee to get it right all the time!

PC

 

[Nemesis]

It sounds interesting stuff, I think my ma in law maybe had it, used to do it over with Cardinal Red.
Sad though - the original floors under so much of these later screeds were far superior, really. But not nice and modern, of course!

 

[Gareth Hughes]

Magnesite flooring is electrically conductive and so an electrical resistance moisture meter will give a full scale damp reading even when the material is bone dry.

I wonder how much pointles and unneccessary work that little quirk has led to?

 

[AMc]

Chunks I stuck my multimeter wouldn't give me a resistance reading even on 2000KOhms and wouldn't conduct 9V from a PP3 battery either down to the 200mV range. So whatever it is it isn't conductive.

Here's a better picture of a piece about 2" across.

 

[Nemesis]

Actually, the pic is a cross.

Tiny red one, nowhere near 2" across!



No doubt that glitch can be mended. (and indeed now has been...)

So - looks like it's not the stuff PC mentioned, although that's an interesting diversion into building materials.

 

[AMc]

Actually, the pic is a cross.

Tiny red one, nowhere near 2" across!

Ho Ho Hi
I was trying to work out why it wasn't showing up - then finally twigged that although I'd tagged the page properly I'd neglected to actually upload the new image to the server - doh!

Still I'm only mildly interested in the red stuff I'm pulling up - more interested in how to get the pitch/tar/bitumen off the floor that remains. Knowing what it is would help, but I suspect trial and hopefully no error are going to be needed.

 

[Nemesis]

Strippers of Sudbury does a remover that removes bitumastic paint, so I suggest a call to them. Try a small area first though!

The tilesoc has some information on care of tiles, yours are unglazed and similar to encaustic.

http://www.tilesoc.org.uk/tile-ceramic-conservation.htm

I'd take care with the red stuff though, you never know what contains asbestos. See above. It was used in all sorts of products. Nasty.

 

[AMc]

I can be confident it doesn't contain asbestos because a sample was tested when the whole project was surveyed (see earlier post) - I just never found out what it was.

It took less than an hour to lift the whole kitchen's worth, it came up in great big heavy sheets, some a couple of feet square. I'll give it a couple of days to dry out, then sweep and see how bad the problem is before I buy a bunch of specialist cleaners. There is always the option of cleaning after I've pulled them up which may be easier.

 

[AMc]

As an addendum - the bitumen stuff dried after a few weeks on pallets outside and a pressure wash was all that was needed.