Help!: Possible adhesive problem... advice needed

[BigBob]

Hi all, first post, great site

Picked up a lot of useful tips on here that have enabled me to successfully (touch wood) tile my bathroom walls and so feeling full of beans decided to have a go at the floor. Starting to regret it... A bit of info:

The floor is screed with black asphalt/bitumen residue from old thermoplastic tiles so I've removed as much residue as possible and put down an SBR slurry coat.
The tiles are vitrified, glazed ceramic (33x33cm). The adhesive is Keraflex Maxi.

I only had time to put down about a square metre or so on Friday and kept the family off them until Sunday night when my eagle-eyed son helpfully pointed out that one of the tiles was wonky. I decided to lift it to relay it and expected it to be a difficult job but it came up very easily and the adhesive underneath had a crumbly, biscuity texture and scraped up with no problems. Thinking this must be a problem with the adhesive I tried another tile and it popped up easily again. So, question is, is this down to wrong bad adhesive/substrate/tile combination? Or does it take Keraflex a really long time to cure fully? Please help before I go back in the bathroom and start popping up the rest (it's like picking at a scab, I can't stop!). Any help appreciated.

[Del W]

Welcome to TF.Did you mix it correctly? Is the addy out of date?

[BigBob]

Cheers and thanks for the quick response Del - I mixed it as per bag instructions and the addy was produced 3 months ago. I just gave Mapei a ring and they reckon that it's most likely the case that it is just taking longer to dry out due to the cold weather (and my bathroom rad was removed last week). The technical chap recommended heating the room up a bit and leaving it for a few more days and then trying to lift another one to compare. I'll kick myself if it's that as I've given the radiator to the tat-man! Ever had any issues with temperature?

[Del W]

Why not give rapid set ago,just mix small qtys,

[Dave]

Slow setting adhesive times are based on 20dgs cels, so yes it will take longer to dry and gain tensile strength...if the room is cold.. it can double the setting time if cold and the substrate is not that porous... the crumbly effect will be the adhesive starting to set but still soft enough to break up..

IMO i would have left it longer and try to introduce heat into the room to aid drying..

[mhtiler]

i would use RAPID set flexible ,never had any problem,hope this helps.

[BigBob]

Brilliant, thanks to you all for the input. I'm a bit more reassured that the adhesive is working (slowly!) - my only previous experience with similar adhesive was with BAL SPF and that seemed to go rock hard fairly quickly but then again it was a couple of months ago when the temperature was higher etc.

Is the rapid set OK with vitrified tiles? If so I'll nip out and buy some (Keraquick? - seems to be popular across the forum). In the meantime I'll turn the heating up a bit and keep an eye on the laid tiles.

[AliGage]

This is your first time tiling a bathroom floor? Can i suggest that if you are going to use rapid set adhesive then set out and cut all your floor tiles ready before mixing up. Use your spacers as you would when fixing. Lift the tiles once they are all cut, remember the order you lift them. I usually place a bit of masking tape on the face of the tile and number them in an order.
I suggest this because rapid set can go off rather quickly. You won't need time to cut or negotiate any issues whilst you have your mix sat there going off in your bucket.

[andy8758]

Rapid set adhesive is an excellent tool to help tilers with specific needs i.e. complete job in a day, allow floor to be walked on soon after tiling, allow fix and grout in a day, tile ceilings (recesses and around windows rapid set is very useful with heavy tiles where adhesive grip may be compromised). The temperature of the water used to mix the adhesive is as important as ambient temperature and even on a cold day/in a cold room setting times can be improved simply by mixing adhesive in hot water - but beware the open time may reduce dramatically too - mix small amounts only - and complete awkward cutting before mixing.