Floor tile adhesive won't go off

[anta]

In a shower room at a small campsite on a farm. We've made a sloped concrete floor for the shower which I've put floor tiles onto using waterproof tile adhesive and grout. That appears to have worked absolutely fine. The sloping shower floor is separated from the rest of the cubical by a small two brick high wall. I've used the same adhesive and same tiles to tile the sides and top of this wall, using plastic tile edging strips at each top edge. This is basically a step into the shower. For some reason the adhesive under the tiles on the top surface of this wall hasn't set after nearly 3 weeks. On the sides it's stuck to the point where my fingers can't remove the tiles. The bricks are some left over block paving bricks from another job. The adhesive had set on the cement between the bricks, but not on the top of the bricks themselves.

Any suggestions as to what's going on?

Ant

 

[joe-90]

You've used the wrong adhesive. You should have used a dry cement based adhesive that sets chemically.

Think about this: When you put the lid on your tub of adhesive it doesn't set, right? Well if you use a type of brick that doesn't allow moisture ingress then it works like a lid on a tub and that's why it hasn't gone off. That's also why it has gone off on the mortar course.

 

[anta]

OK - I see your logic. So why has it set on the sides? Has the moisture of the adhesive effectively run down and soaked into the concrete floor either side?

Ant

 

[joe-90]

Dunno but it's either gone somewhere or dried in the atmosphere. That's how the stuff sets. You have to lose the water content.

 

[roughcaster]

Joe90 wrote,

You've used the wrong adhesive. You should have used a dry cement based adhesive that sets chemically.

Joe's right.

Roughcaster.

 

[jefoss]

did you tile then grout straight away?

 

[anta]

did you tile then grout straight away?

No. I left it 24 hrs but realised that these particular tiles hadn't set. Left it another 48 hrs and it seemed ok so I grouted it all. That was 2 weeks ago.

Hey ho. I'll know next time. I need to find a small quantity of cement based floor tile adhesive now as there's only 1.5m x 15cm to do.

Ant

 

[gcol]

You can always stick the tiles down with a grab adhesive like Gripfill if it's just a small area.