help please im new! dusty concrete floor - sealed with granocryl is this ok?

[jools]

Hello all!

I'm new here (first post) so i hope it isn't a dumb question, please help!

I've had an extension build with a concrete floor. the surface of the concrete is very dusty, you can just sweep and sweep and the piles of dust just keep coming!

I was advised to seal the floor with a stabalizer (which i've just done).

Not knowing anything about stabalizers, I opted for Granocryl masionary stabalizer (made my leyland paints). The label says it penetrates concrete, binds loose and chalky surfaces, and provides a sound base for water bourne masonary paints. It was the nearest thing I could see for my requirements to seal the floor and bind the dust, so I bought it and have given the floor 2 neat coats.

It's only now I've found this forum, that i am starting to worry if i've done the right thing! (or not)!

Part of the extension is going to be a utility room with a tiled floor. i have bought 300x600 porcelean tiles. I've not got any adheasive or grout yet.

My questions

will the granocryl stabalizer be ok to tile on to??? (it dosen't mention tiling on the tin).

will I need to use a seperate primer??

and any other advise on adheasive and grouts would be most welocme. (area is 3m x 5m)


Thanks so much

Jools:smilewinkgrin:

 

[White Room]

I've done similar with sbr but don't know of the product you have used but sounds credible.

I would have poured some so it penetrated deep into the screed.

Does it feel like it firmed up the surface.

 

[jools]

Hello, thanks for yor reply.

I've only just done it today, so not sure of results yet. It hasn't left a glossy smooth surface or film on top, so I am assuming that it has penetated. I thought about pouring lots on, trouble is it anit cheap and althought the area I am tiling is only 5x3m the whole area is 30sqm. I have used it librally (as stated on tin) and its had 2 coats. but the tin said it would cover 6-8 meters per litre, i was lucky to get 6 metres out of a FIVE litre tin (and ive used 5 tins of 5L so far)!

My main concern was would this Granocryl product be ok and compatable to tile onto?

Will I need a seperate primer, and will this be ok now ive already sealed it with something else?

(I read the thread about PVA sealing being a no no and then started to read about all the different stabalizers and primers, so i hope I've used the right (or at least compatible) stuff?

Thanks again and any more advice on compatability most welcome

Jools

 

[White Room]

I just tried to do a search on it and can't find nothing

Sounds like you have used enough anyway..

I would use an sbr sealer before you tile.

 

[Ajax123]

Think granocryl is an acrylic dust stabiliser. If the concrete itself is sound then it should work but the dusting at the concrete surface is a defect in itself and needs to b e investigated,

The usual cause of dusting like this is the concrete dessicating or drying out too quickly from the surface. It is also often accompanied by cracks but not always. It is the reason why concretes should be cured to keep in the moisture but it is what it is so you now need to deal with it.

Firstly on the basis of the defect you would have presumably been better to get the builder back to sort it. but again it is what it is.

Now then the only way to be sure what you have done has worked and not just created a shell on the top of the concrete will be to carry out a surface tensile strength test but you won't have the gear to do that. My suggestion would be to speak to someone like BAL or Ultra and see if they can help you with this. It will mean using their adhesive of course.

My gut feeling with this type of product on this type of problem is that it won't have stabilised the concrete deeply enough I am sorry to say...based on experience. You may need to run a floor scarrifier over the concrete to reopen the surface and use a low viscosity penetrating epoxy. These are not cheap but they will do the job. The other option is to take to top surface off the concrete to remove the sealer and get hold of some Lithurin DiHydrochloride salts...most good concrete suppliers wil be able to source this for you as it is a standard repair for dessicated concrete. I know that Lafarge can get it so if you need a contact to talk to let me know

Sorry to be negative but if you have just created a hard shell on top of a weak concrete your tiles will stick to the top of the concrete but will fail due to the concrete itself breaking just below the shell. The other alternative might be to screw hardibacker board down over the whole lot to give you a firmly fixed sub base....assuming you can get screws and plugs to hold in the concrete.

For simplicity I personally would do the latter...in fact I did on my utility room floor recently.

 

[jools]

Hello,

Thanks for your reply,

The concrete slab itself is rock hard, I had to drill it to put studs down for interior walls. Infact it was easier to drill the concrete blocks on the walls than the floor slab.

Its just the surface that is dusty, as it was left to go off with a bit of water on top. The surface was chalky, but the stabilizer has worked relatively well, just painting the untiled area with floor paint now.

I was more concerned weather the Granocryl Stabilizer was (tile friendly), as a sealer, or whether it was compatible with primers (such as the Bal STR that was mentioned above) by Whitebeam.

Thanks again

Jools