Pulled up some old self adhesive vinyl tiles in a porch today, thin layer of self levelling compound came up with them, leaving a sub floor of really friable concrete screed. Could be crumbled in your fingers.
Tried PVA, helped a little but I conclude that whoever laid the screed didn't use the right mix in the first place.
No point trying to lay anything on top of the screed, so any alternatives to digging it all out & starting again?
More PVA, different mix (I used 5-1)?
Sounds OK. It must actually soak in -- is the floor sufficiently porous? Did you leave it to fully dry? (Possibly hard to tell if it soaked in - might need to check a day later. Soaked-in isn't the same as dried.)
About a gallon of diluted PVA.
Let it soak right in.
>On Thu, 23 Apr 2009 17:10:55 GMT, "The Medway Handyman" had this to say:
Angle grinder.
HTH -
Like a sponge.
Ah. Left it for about 2 hours, maybe it had just soaked in.
pour until no more will go in, and leave a week.,
I'd use cement slurry with pva in it as well. The cement is waterproof, pva isnt. Its also stronger.
NT
Cement or mortar slurry?
Cement - its works as a tanking solution when mixed with PVA in some cases IIUC.
John Rumm coughed up some electrons that declared:
Think I'll try that on some loose patches on my floor (some bits seem as described here - 99% sand 1% cement).
If the floor is damp and needs tanking, use EVA rather than PVA in the slurry. (It's usually sold as Exterior PVA.) SBR is another choice, or a proprietry tanking cement.
Andrew Gabriel coughed up some electrons that declared:
Of course - I know EVA as a woodglue. Never thought of it in the same general purpose light as PVA
I'll look up that tanking cement - sounds interesting - ta
No sign of damp, but I reckon the same bloke mixed it.
just cement & water. On 2nd thoughts I'd maybe leave out the pva altogether, it will only thicken the mix up and retard the cement penetration, and cement does a far better job of cnsolidating a floor than pva ever will.
NT
just cement & water. On 2nd thoughts I'd maybe leave out the pva altogether, it will only thicken the mix up and retard the cement penetration, and cement does a far better job of cnsolidating a floor than pva ever will.
NT
Maybe someone could advise me here... I want to make a very weak mortar mix, bare minimum cement content, to make blocks that will be cast in plastic containers, and stay in them forever more. They'll only ever see trivial loads, theyre just static weights effectively. It doesnt matter a monkeys if they crack into 8 pieces, the only requirement is they dont disintegrate so badly that they empty themselves out through 5mm holes. How weak a mix can I go? 12:1?
NT
You're kidding of course. Have you ever tried it? There's a good reason why these additives are so widely used. No floor covering manufacturer will guarantee their products without proper screeding.
Probably... they say 10:1 is enough to stop the sand migrating under the influence of water under paths etc, so since yours won't be getting wet, a tad weaker would not hurt. (then again the difference in cost of materials between 12:1 and 10:1 is going to be next to nothing)
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