Anhydrite screed question - TilersForums.com

[Matthew77]

It's the same one as the link that Radim just put up.
What adhesive have you been advised to use on the job?

There were a few suggestions but I decided to go with Anhyfix by tilemaster as it was fast setting and I already use their level flex leveller and ultimate flex adhesive on certain jobs and have been very happy with both of those products.

So the machine Radim posted is a sander that uses silicone carbide type abrasives which is the same abrasive pads i started using originally at a 60grit these seem to be doing nothing now!

 

[judge]

Ive not had one job where the latience has been removed.Only the jobs that ive been involved with from the start and removed it myself after 7 days.Nobody seems to advise on latience removal.I still get "i was told a mm a day to dry !" with most the jobs i look at.:smilewinkgrin:Oh,ask your local hire company if they can get you an"STR" with a copper plate.

 

[Matthew77]

Would anyone be able to please explain to me why if the laitance is stuck so well to the screed that the sanding pads are having real trouble removing it why it can't be tiled onto....then I can relay this information back to every other trade that asked me every 10 mins why i can't just tile straight onto it as "its obviously fine to tile onto"?

 

[Matthew77]

Ive not had one job where the latience has been removed.Only the jobs that ive been involved with from the start and removed it myself after 7 days.Nobody seems to advise on latience removal.I still get "i was told a mm a day to dry !" with most the jobs i look at.:smilewinkgrin:Oh,ask your local hire company if they can get you an"STR" with a copper plate.

yeah I get the classic "its defiantly dry now" after 2 weeks, which I reply "nah its defiantly not dry yet" which then comes" we've had the window open, Its defiantly dry"

Could you please explain what an STR is?

thanks

 

[Stef]

Would anyone be able to please explain to me why if the laitance is stuck so well to the screed that the sanding pads are having real trouble removing it why it can't be tiled onto....then I can relay this information back to every other trade that asked me every 10 mins why i can't just tile straight onto it as "its obviously fine to tile onto"?

The surface layer is a friable layer that must be removed.
All the contaminates that are in the screed float to the surface.
I'm not exactly clued up from the real technical side of these screeds, our resident expert Ajax is the technical guy for explaining it.
I have never tiled to an calcium screed without the laitance being removed & I never will.
AnhyFix is the adhesive to use, it's sticks like the proverbial.

 

[Matthew77]

The surface layer is a friable layer that must be removed.
All the contaminates that are in the screed float to the surface.
I'm not exactly clued up from the real technical side of these screeds, our resident expert Ajax is the technical guy for explaining it.
I have never tiled to an calcium screed without the laitance being removed & I never will.
AnhyFix is the adhesive to use, it's sticks like the proverbial.

Thanks at least by the sounds of it I have chosen the right adhesive!

I don't plan on tiling onto it without the laitance being removed either as everything I've read about these screeds the emphasis seems to be on removing the laitance and making sure the screed is dry. Its a shame theres not a bit more info around regarding the importance of the removal time of the laitance as it is hard as hell now!!! I've tried floor scrapers, a saw blade in a floor scraper, wire brush attached to an angle grinder and nothing seems to want to touch it!

 

[Stef]

The link that Radim put up is a floor grinder, it's got replaceable pads on it.
If that doesn't remove the surface laitance then nothing will.

 

[judge]

Here you go mate http://www.brandontoolhire.co.uk/en/surface-preparation/534-floor-preparation-system.html

 

[Matthew77]

The link that Radim put up is a floor grinder, it's got replaceable pads on it.
If that doesn't remove the surface laitance then nothing will.

So just to clarify, in my picture the light parts on the floor are laitance free and the darker parts are the laitance that need removing? I'm only asking this as i went over the top of the darker bits (with a new sander belt on) and let it spin over the same place for a few minutes and all it seemed to do was make it darker in colour!!

 

[Matthew77]

Here you go mate http://www.brandontoolhire.co.uk/en/surface-preparation/534-floor-preparation-system.html

Thank you.