'patching' a concrete floor

[Neal Harwood]

I am about to lay some laminate flooring in the basement The current floor is nice level concrete, but with a few bits of damage(?) these are shallow 'puddles'(i.e. holes where water would form puddles, if there were any water) - no more than 1 cm deep, but one is about 4 cm across.

I would like to 'patch' these holes somehow, before laying the underlay and flooring on top.

1)should I use ordinary cement? I am worried this might not stick, and as a result come loose and cause bumps under the floor.

2) Should I use something else? Some kind of hard, adhesive filler? Recommendations?

Neal

[chris French]

In message , Jan Wysocki writes

for shallower depressions I would use self levelling compound - which is just a cement based mixture that can be used in quite thin layers.

[Jan Wysocki]

Yes, use cement with sand to make a render: Spray the depression with diluted PVA adhesive to ensure a good bond. (Add enough water to make the PVA flow easily, or you could just brush it onto a small hole.) Mix 1 part cement to 4 parts builders sand by volume, then add enough water to make it thoroughly damp, but without excess water. If you squeeze the mix, there should be no excess water if there is, then mix in more cement and sand. trowel it into the hole and press and wipe with plenty of pressure to make it smooth and level. Cover with plastic sheeting for 24 hours to allow it to set without drying out.

Well, for a small hole "Plastic Padding", exterior Polyfilla or anything that sets hard, sticks to concrete and resists damp should do.

[stuart noble]

A PVA mortar works just as well if there are no damp problems and saves you buying 20kgs of the stuff.

[Grunff]

PVA mortar is great, but the only thing you can't do with it is feather it really thin, because you're limited by the sand grain size. Cement based self levelling uses much finer dust than soft sand, so allows you to feather it down to almost nothing.

[stuart noble]

I don't think the self-levelling stuff is cement based. Cement coloured certainly, but some strange kind of mineral that IIRC doesn't set without the latex binder.

[David]

In article , stuart noble >it really thin, because you're limited by the sand grain size. Cement

It is based on cement, sometimes a blend of OPC and HAC, the material is a concoction of water reducers, super plasticers, accelerators, polymers and (done correctly!) will far out perform a latex screed, show me a latex screed that will go down at 3mm thick and take forklift traffic without failing and I'll bare me bum in Burtons window

[stuart noble]

But the self-levelling products I've seen and used ARE latex screed. What product(s) are you referring to?

[Grunff]

The one I used wasn't. It was just cement based with a fine filler. I can't remember who makes it - came from local builders merchant. It was definitely non-latex, I've seen those, and they have a very different texture.

[David]

In article , stuart noble >>certainly, but some strange kind of mineral that IIRC doesn't set without

A latex screed is a sand/cement with a liquid added as well as water to give a workable screed to be trowelled on. Self levellers are not latex based, the term is polymer modified and latex is far from being the only polymer

[stuart noble]

The self levelling screeds I've used contain no sand, and no cement although, as I've said, they are similar to the colour of cement. The dry ingredients did not set when mixed with water alone.

These were based on a styrene butadene coploymer, which is what we in the UK call latex.

[David]

In article , stuart noble although, as I've said, they are similar to the colour of cement. The dry

You're not talking about resin screeds are you i.e. epoxy, polyurethane etc. I don't know of any powder screeds that are not based on cement, the polymer additives are inert and won't cause anything to set as such you may get a certain amount of hardness when the liquid dries out and sticks the particles together

err no we don't, latex has become a bit of a generic term and it certainly isn't just Styrene Butadiene Rubber, there is Styrene Butadiene Latex which is used for carpet backing etc but not as an additive in floor screeds.

[chris French]

In message , stuart noble although, as I've said, they are similar to the colour of cement. The dry

The stuff I used most recently was Evostick Self Levelling Floor Compound - it certainly was cement based (+ whatever else goes in them) and I certainly did just mix it with water, and it certainly did set :-)

Obviously different types of products here.

[stuart noble]

Last time I bought some, Builder Center did two types of self levelling screed. One was a powder with no liquid additive (I guess incorporating a dry PVA), and the other came with 5L of the above polymer (aka SBR).

[David]

In article , stuart noble writes

The "just add water" types do indeed have a powder polymer in them of which there are many, when formulating there are so many different ways to go and chemist would tend to have their favourite suppliers or type of polymer and would use that as a starting point.

[stuart noble]

By its price I would guess that SBR gives the best performance but cannot be incorporated in a dry form.