Floor Slab

[karoo]

Hi,

Just had builders to lay an internal slab laid in my new kitchen extension and I am not very happy with it. Its been down about 2 weeks now and although I expected it may be dusty I can actually rub it with my finger and rub a groove into it untill I hit aggregate. I don't know if the mix is weak but is there any treatment that can be applied to repair the surface and consolidate it and give a hard wearing surface?

Thanks for any input

Karoo

 

[^woody^]

That is normal

 

[karoo]

Thanks for the reply Woody but I proberly could describe it better. Even brushing it with a soft brush brings it up, its not dust but granular like sand. I suspect that if I tiled the floor once the adhesive had set the tile would lift as there is nothing solid for the adhesive to stick too.

Hope this helps

 

[theoldun]

That is normal

Well woody, without wishing to correct you, all we will say is that if by some chance, we had laid a C20P slab, be it ready mix or site mix and after 14 days we could rub a groove in the surface with our fingers, then we would be looking to take out the defective concrete and replacing.
Regards oldun

 

[karoo]

Well, my original question still stands. Does anybody know if there are any products that can be applied over the surface that will repair this problem without having to remove and relay the slab?

Thanks for any advice

 

[noseall]

There are concrete sealers available but why bother?

If it is your intention to leave the floor exposed for whatever reason then drop an old rug over it for now.

And if the above was the case, then why did you not go for a separate screed instead of a trowelled slab? It is not easy to get a decent finish on concrete without the aid of a powerfloat and a skilled concrete bloke.

 

[karoo]

Thanks for the reply Noseall but as I stated if I applied ceramic tiles to the slab the (concrete surface can be rubbed away even with the flat of the hand) I would think I would be able to lift them once the tile adhesive had set as a finger can rub a groove into the surface there would be nothing for the adhesive to bond/hold on to. Thats why I would like to know if anyone knows of any product that will "repair" the surface.

Thanks

 

[^woody^]

It's not clear why your builder just laid a concrete slab without a screed surface or if no screed is to be used, without towelling it smooth which would then form a harder surface.

You may have a poor specification

You can get dust-proofers and sealers to harden the surface. Or you could apply self leveller before your floor finish

The point is, a grainy surface does not necessarily mean a defective slab

 

[simonjay]

Thanks for the reply Noseall but as I stated if I applied ceramic tiles to the slab the (concrete surface can be rubbed away even with the flat of the hand) I would think I would be able to lift them once the tile adhesive had set as a finger can rub a groove into the surface there would be nothing for the adhesive to bond/hold on to. Thats why I would like to know if anyone knows of any product that will "repair" the surface.

Thanks

Sounds like whatever it is, it may be a little dusty or sandy.
Does it seem stronger once you to get to aggregate ?

Screed or whatever should be primed with 4:1 SBR to water to stablize before tiling, and that would solve any problems with tile adhesive.

Simon.

 

[karoo]

Thanks simon, it does get better as you hit the aggregate.

What is SBR?

Thanks to everyone else for your input