fixing to paving slab

[marcros]

I need to fix a flange to a paving slab. The flange is about 10mm thick with 2 large holes (17mm?) predrilled, the slab is only about 20mm thick. what is the best way of doing it?

I cannot use through fixings because the slab has no clearance underneath. It is being used as a parasol stand/guide through the centre of a table. Into the flange is a piece of tube which is fixed at the other end into a flange secured to the underside of the top. The base itself is a Gabon basket filled with stone, which sits on the slab. I haven't filled this yet, but I would think that there will be 50-75kg of stone in there, based on 2-3 DIY size bags.

I haven't used many anchor bolts, but they always seem much longer than this.

 

[gregmcateer]

Can you post a photo?

 

[marcros]

no, but

The finished table will look like https://www.containerwatergardens.net/w ... or-bar.jpg

but with a hole in the middle for the parasol. To keep the hole open, I am going to have a pipe down the middle, so have got

1 of https://www.keyclampstore.com/base-plate-60mm-132-60-e at the bottom (to be fixed to slab) 1 of https://www.keyclampstore.com/wall-plate-60mm-131-60-e at the top, and a length of tube in between.

I am thinking that some form of resin and a threaded rod might be the way forward.

 

[Rorschach]

20mm thick is too thin for anything other than a through fixing, can you make clearance?

 

[gregmcateer]

If the top is supported sufficiently and secured by the basket, could the flange be 'glued' with e.g. epoxy resin, to the underside, as it shouldn't be doing and major work - just locating and stabilising the pipe?

 

[marcros]

I did wonder that, although if buying the resin, the extra effort to glue and to glue in a bit of threaded rod may be worth it.

 

[MusicMan]

I would use a threaded insert to take an M10 bolt, plus resin. You'd get a bit of mechanical grip by the screw of the insert. As suggested, also spread resin on the flange itself. Perhaps cover the assembly with sand before the stones go in to get an even pressure. The threads on the insert have a deeper profile than regular threaded rod, so give a bit more grip.

https://www.amazon.co.uk/PACK-20mm-DRIV ... B075B3XP15

 

[novocaine]

I wouldn't use a flange at all, I'd overbore the hole and use a bushing.
you could use your wall bracket upside down, I'd most likely countersink it in to the surface to give a nice flat top. then glue it in with a decent external grab adhesive.
As i'm cheap I'm be more inclind to use a random bit of pipe myself.

 

[marcros]

I could have used a random bit of pipe, but I would have had to buy it. I am envious of everybody with plenty of scrap and offcuts, and these little places that will weld for a packet of biscuits!!!!

this was the cheapest option I had, and was actually cheaper than the links.

 

[novocaine]

it's ok, I often wish I had other folks stuff too. then I go in the workshop and wish I had less "stuff".
still think you'd be better with it flipped over and set in the slab rather than trying to bond it to the top.

 

[Lazurus]

I did a similar thing with 4 x gazeebo legs, I simply used big rawlplugs and stainless roofing screws, worked a treat

 

[MusicMan]

The 10 mm bolts in threaded inserts will stop sideways and vertical movement. You are only protecting against the leverage of a sideways force on the tube. I am sure that the weight of the stones in the gabon will do this, but if you want some belt and braces, then you could slosh some concrete mix around the flange and base, thus building up the thickness on top.

Keith