Slab will not stick down

PCAnimal · 16 May 2015

Hi, I've laid 47 sqm of patio and I've had a few which needed relaying. THe others are solid as a rock. I laid them on to compacted hardcore using 6 to 1 mix.

However for reasons which defeat me I have laid this tile 6 times and not once has it even remotely stuck down. I've tried 2 tiles but that made no difference. Can anyone suggest what I am doing wrong or more importantly what I need to do right to lay it!

On another note you see I've got some raised steps which need slabs laying on them. Should I be using a different mix for these because the base is concrete?

Many thanks

Justin View media item 94436 View media item 94437

footprints · 17 May 2015

I suspect the mix is dry and wetting the back of the slab will help.

PCAnimal · 17 May 2015

It was a wetter mix and I did wet the back of the tile.
I've been told to use a latex adhesive on the back of the slab. I've only used that for putting up tiles on the wall

footprints · 17 May 2015

You could try a bit of waterproof pva brushed on the back and maybe a bit in the mix but I can't see why it is not sticking with a damp slab and wet mix

PCAnimal · 17 May 2015

I will give this a go thank you.

When I do the steps should I use a different mix ratio?

r896neo · 18 May 2015

if you have got steps to do too then buy a tub of sbr and coat the back of the slab with a slurry of 1 part cement to 1 part sbr to 1 part water. then lay the flag while its still sticky.

For the steps do the same to the concrete base and add about 100ml of sbr to your gauge of mortar.

footprints · 18 May 2015

I tend to go 1cement to 5 sharp sand mix but some say as weak as 10 to 1 so I don't think your 6 to 1 is the problem I would use the same for steps myself.

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Slab will not stick down

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