Concrete chemical fixings-- Total numpty question.

[zzr1200]

I've never used or even seen chemical fixings being used/installed...need advice...please..

If I'm using say 14mm studding do I drill a 14mm hole in the concrete or do I drill a larger hole say a 16mm or maybe a 18mm?

I totally understand the hole must be dust free for the resin to work.

I've never liked the rawlbolt type fixings, I have used the drill the same size hole as the stud and hammer it in type (parabolt type) but even these can pull out.

I just fancy trying the chemical route, I know the resin has to cure for full effect.
But unsure of the hole size....

Advice please.

 

[wyn]

The ones that i have done, the holes needed to be 4mm bigger than the fixing.

 

[Dcal]

It will usually say in the instructions or technical data sheet ( search online) but hole size 2 to 4 mm bigger is normal.
What product is it?

 

[Kent]

What an unusual thread size, obviously a reason for that
Yes i use the stuff a great deal. Dust free like you state esential. Likewise get rid of the first bit as it tends to not mix well. Set a good blob to one side then so you van time things correctly for torque up time as different conditions matter.

There is a guide to hole sizes but it eont go 14mm i bet go 2mm up i recon on that one but it largely goes on substate type and you only learn thst by doing.

Esential to blow all the dust out (i use an unused mixing nossle if there is not the ability to use compressed air) .

 

[pedrobedro]

Masonry bolts or Thunderbolts are good if your concrete is sound, no messing about and they hold well as long as you use the correct drill size.

 

[Tommytiptip]

Masonry bolts or Thunderbolts are good if your concrete is sound, no messing about and they hold well as long as you use the correct drill size.

I've used some of these to fasten a fence to a concrete block wall. After 12 months or so ,several had shaken loose from being battered by winds. They were re positioned after some silicone was put in the fixing holes.

I did also use some adhesive to set two threaded rods into concrete by around 12 inches to support a metal chimney base-they worked an absolute treat and haven't budged in 4 years-thoroughly recommended.

 

[pedrobedro]

I've used some of these to fasten a fence to a concrete block wall. After 12 months or so ,several had shaken loose from being battered by winds.

The ones I've used are still solid after 4 years despite winds and gate slamming. They are into engineering brick one side and concrete posts the other. Biggest I've seen are 150xM16 and I think they would take some shifting but the ones I use most are M8 with a Torx head.

 

[Kent]

Well i have seen pull tests and what happens is you get a big cone shape of concrete with threaded stud at the core very firmly stuck in that concreate

Admittedly theres a learning curve on the process and what you can and can't do.. I have been through that in my fith year of use.. The only thing i haven't managed is hollow block because i cant get hold of the correct sleaves.. Let be fair though hollow block is junk and not suited to fixing very much anything to thst nerds to be strong

 

[jsf55]

https://www.screwfix.com/p/rawlplug-rcasv-resin-capsules-m10-10-x-90mm-drill-size-12mm-10-pack/4088f
I've used these, not that particular size, with great results and had a good hammering in there location, not cheap tho !

 

[Kent]

https://www.screwfix.com/p/rawlplug-rcasv-resin-capsules-m10-10-x-90mm-drill-size-12mm-10-pack/4088f
I've used these, not that particular size, with great results and had a good hammering in there location, not cheap tho !

Used them things years ago.. Didnt like them st all ! Did eveything it said and only about50% took
Fsstening armour plate to walls it was Thsnk goodness we could getaway with it as it wasnt holding anything up structural

 

[jsf55]

Used them things years ago.. Didnt like them st all ! Did eveything it said and only about50% took
Fsstening armour plate to walls it was Thsnk goodness we could getaway with it as it wasnt holding anything up structural

never used them vertical was always floor mounted barriers that they used to back the fork lifts into, they never failed just bent the barriers

 

[frank horton]

I always drill 1mm bigger holes in upto 12mm dia after that 2-3mm bigger,,,,,blow out the drilled holes with an air line.......
THEN along the threads that r in the floor I grind 3 grooves about 2mm deep for the chemical to seep upwards...
this way u know the chemical has crept up the holes for sure.......easy to knock off the lump when cured....
diff to say how much chem is needed in the hole but the first 1 always gets a 1/3 -1/2, after that u'll know whats needed.......

also for the first time this week used the concrete screw bolts rec on this forum......amazing.......
only used them for holding the track down for a 6m rolling gate...def use em again.......

 

[Dcal]

THEN along the threads that r in the floor I grind 3 grooves about 2mm deep for the chemical to seep upwards...
this way u know

Sorry @frank horton but that seems like a lot of work for very little gain.
It will work fine though.

I just make sure the chemical anchor is placed in the bottom of the hole (extend the mixing nozzle if it's really deep) and then just push the anchor to the bottom of the hole and it will displace the chemical anchor material and fully fill the full length of the anchor.
Any excess should return out the top and if it doesn't, the hole is too tight for the anchor or it is going somewhere else (like into a cavity!)
Blowing out the holes with an airline is great but a puffer works fine if you don't have access to compressed air.
If you are being really fussy you can buy wire 'bottle' brushes and use them in a drill to roughen the holes. This isn't something g you would normally need and never for block or the like.
You can also clean out the holes with a garden hose and water but you need to let it dry or use an epoxy chemical anchor which can cope with the damp.

Chemical anchor is fantastic stuff and puts a lot less stress on the substrate (concrete, block, brick etc.) than any other type of fixing.
Only real disadvantage is they are not fully removable (easily)

 

[Pete.]

Hilti HIT HY200 resin and a 16mm threaded stud drilled in 200mm will hold at least 9 tons. I know that because I had it extensively tested last year (4 or 5 times at 500 quid a pop). The load I was testing for was 15kn so we tested samples to 30kn and for fun I had him pull one to destruction, it got to 90kn and the nut pulled through the jacking washer, but the stud still held firm.

As for the hole size, that is something you'll find out by checking the spec of whichever resin you're using. They are not all the same. For the HY200 and 16mm stud we drilled 18mm holes (200mm deep as stated above). Getting the dust out of the hole is absolutely essential. Use a puffer, an air line, a hoover or whatever it takes. I had to put my most responsible person on that job because of the very severe consequences of it going wrong (it would have been on national news).

 

[Dcal]

Hilti HIT HY200 resin and a 16mm threaded stud drilled

And if you are installing it in wet cored holes or want an even higher capacity use the 500 grade, which is a lot slower curing (and more expensive) but more forgiving.
Also way over the top for most applications but it amazing the number of times it get specified by consulting engineers for low load applications.

I've tested lots and the bar always fails if the substrate is something strong, like reinforced concrete. (No point in sticking it into a block and expecting massive capacity.)

 

[fizzy]

I have used quite a few chemical anchors and they do work well. The old ones used to be epoxy but they seem to do all sorts of cheaper ones now. Are they as strong? Some are almost like a mortar.

One thing I have thought of as a theory is to coat the stud/bolt in silicone grease. Would you then be able to unscrew it nicely? It shouldn't hurt the strength as you should have nice moulded screw thread.

 

[Hitch]

I was involved with some crash barrier testing sometime ago, all resin fixings. Some serious strain went on it. The concrete (very stong stuff) started spalling before any sign of the resin giving up.

Most resins ive used are +2mm for under 20mm, so 14 for M12, 18 for M16... and M20 and above is +4mm so M24 is 28mm holes.
Get the data/instruction sheet for the resin you want to use, it will say on there, if not on the packet.

As stated above, clearing the hole from dust properly is a crucial step.

 

[Pete.]

Resin anchors are not designed to be removable. If you wanted to be able to remove the fastener you'd use a socket.

 

[Hitch]

One thing I have thought of as a theory is to coat the stud/bolt in silicone grease. Would you then be able to unscrew it nicely? It shouldn't hurt the strength as you should have nice moulded screw thread.

You use insert things in that instance. Basically a bigger stud, with a female thread inside.

 

[Wallace]

I bought stud a kit of Ebay, I think it was for M16 and came with a drill bit and rotary wire brush. The studs were cut down then drilled and tapped M10 so they sit flush with the floor. I used the shop vac 3/4 covering the hole to let air in with a final air blast after 2 or 3 goes with the rotary wire brush then gave each hole a good squeeze of goo. With a bolt in each stud with a large washer to set the depth, I rotated each fixing in the goo to get good coverage on the stud and hole then wiped the excess off once fully home. Judging the amount of goo is an art that would come with practice. Have to say I was sceptical at first but now I’m converted.

Edit: Must type faster!