Concrete floor levelling - Cement / PVA slurry?

[Mike]

Hi Found this great old thread which seems to be the answer to my problem of levelling a concrete floor where thickness required is too much to use standard self-levelling compound and too little for standard screed. Relevant bits:

" The only real solution is to bring the whole floor up to the same level. There are lots of ways of doing this for a 10mm level difference. You could use a runny concrete slurry as a thick self levelling compound (most self levelling compounds can only be used up to around 3-4mm thick, which is why you have to make your own slurry)." "We did this in one of the rooms in our last house. Just mixed up a slurry using cement and fine sand (1:4), using PVA in the gauging water (around 1:4 PVA:water). Worked great."

Just wondering if anyone has tried the 'PVA cement slurry' as described and knows how wet you can get away with making the mix without problems. My plan is to mix it properly runny so that it does actually self-level but unsure if this will compromise set strength? A ratio of pva water : dry mix would be really useful if anyone knows? Thanks in advance for any help.

[Andrew Mawson]

problem

Not quite the same, but I have a concrete path round my workshop that had to have ends that feather to virtually no thickness so I could roll a pallet lifter on it. I used sharp sand, generous cement (1:4 I think) and a very good dolop of PVA in the mix. Adjacent concrete was first brushed with 2:1 water:pva to give a bond. So far it has stood up to heavy wear very well and not cracked away as I expected despite loads of well over a ton rolling on it. As an aside, I had just laid it and cleaned up when we had heavy rain, which gave it a very attractive dappled (or as I call it non-slip) finish !!!

AWEM

[Stuart Noble]

Alas, nothing sets level by itself. If it's too runny, the sand and cement will settle out under the water in a random fashion. IME the 1:4 PVA works fine, even down to a feather edge, but it has to be thickish i.e. it just about slides off a metal trowel and lands with a thud rather than a splat (very technical :-)). I suggest using the bagged general purpose mortar for this, or plasterers sand if you're mixing your own. Sharp sand can be a bit too coarse. The most useful tool for levelling is a length of wood a foot or so shorter than the width of your room

but unsure if this will compromise set strength? A

[John Rumm]

The latex mix you get from wickes can be used mixed with sharp sand to fill deeper sections first. Then just screed the lot with a normal latex mix after that has started to go off. I have feathered that down to nothing without any problems.