Glue for a stone slab?

[bungeejumper]

Dammit, dammit, dammit. We bought half a dozen beautiful square limestone slabs the other day for the princely ransom of fifteen quid! About two square metres in all, and just 40mm thick, which is ideal for a small pergola arch. And as I was cutting them to size with the diamond disc, a pre-existing crack opened up in one of them, and so now it's in two pieces which, naturally, fit together invisibly. Grrrr.

Since the slabs are square and clean, the memsahib would rather go for a near-seamless join than to mortar them up and let the crack show. We'd originally planned to bed them into sand, but it wouldn't be that much of a bother to lay them into a wet concrete screed instead. The question is, is it worth trying to repair the break first, and with what?

The only glue I'd trust to stick (clean) stone is the all-American Gorilla Glue, which is really pretty good in my experience. The problem is that it expands as it sets, so that would rather knacker the idea of a seamless join. I've used PVA successfully in the past, but this time I'd want a bit of strength in the join. Any suggestions? Attach a bridging piece of stone underneath, for instance?

TIA

BJ

[ReformedCharacter]

Araldite?

RC

[pochisoldi]

Drill holes in either side and install dowels made of a suitable material?
Care would have to be taken to ensure that water cannot penetrate the dowel holes to avoid freeze/thaw damage.

[kiloran]

I've no experience of this, but it sounds like you are on a loser.... the crack is bound to show over time.

I cannot see glue working for long. Perhaps metal straps on the underside, held by screws? But careful when you are drilling the screw holes

--kiloran

[Dod101]

Return it to the supplier and see if they will replace it, for free is poss.

Dod

[bungeejumper]

Return it to the supplier and see if they will replace it, for free is poss.

Nice thought, but the slabs were lying in a skip at the local stone flooring specialist, who had just ripped them out of some film star's bathroom. We rescued them from the hardcore crusher!

Very many thanks for all suggestions and comments. We're now resigned to laying a concrete screed, so we can simply bed the stone onto it and then it'll be fully supported. I like the idea of pegging/pinning the break together from underneath, though. I'm having a try with the Gorilla stuff, which is fearsomely strong - the only proviso being that you have to clamp the workpiece really tight, because otherwise the glue will try to force the joint apart as it expands. Will report back on how it goes.

Thanks again!

BJ

[jfgw]

You could stick it to a cheap concrete slab. Tile adhesive should work well - the cheapest grey non-flexible sort would be sufficient.

Julian F. G. W.

[AsleepInYorkshire]

Return it to the supplier and see if they will replace it, for free is poss.

Nice thought, but the slabs were lying in a skip at the local stone flooring specialist, who had just ripped them out of some film star's bathroom. We rescued them from the hardcore crusher!

Very many thanks for all suggestions and comments. We're now resigned to laying a concrete screed, so we can simply bed the stone onto it and then it'll be fully supported. I like the idea of pegging/pinning the break together from underneath, though. I'm having a try with the Gorilla stuff, which is fearsomely strong - the only proviso being that you have to clamp the workpiece really tight, because otherwise the glue will try to force the joint apart as it expands. Will report back on how it goes.

Thanks again!

BJ

Break them all !
Not the best example but it sort of gives you the concept
https://www.youtube.com/watch?v=PE0Vtmzvlxo

AiY

[bungeejumper]

Break them all !
Not the best example but it sort of gives you the concept
https://www.youtube.com/watch?v=PE0Vtmzvlxo

I like your style. Actually we've crazy paved a couple of smallish garden areas, using old stone that's turned up in the borders (it's an old house), but this time the memsahib wants the slabs as slabs.

Have got the slab almost seamlessly together now - so far, so good - and will set a solid concrete base today, so that it doesn't have anywhere to move to. Maybe it'll work, maybe it won't. But my next job is to get the damn Gorilla Glue off my fingers!

I did have a surprise, though, when I googled Gorilla Glue - it seems that there's an entire alternative level of meaning out there. Don't bogart that joint, my friend.

BJ

[forgotusername]

I've successfully used waterproof pva to join things like broken roof tiles or terracotta pots. Once hardened and bedded on mortar, I doubt the two halves would separate and it would be practically invisible.