Fixing bolts in concrete?

[michaelmorris]

I'm about to install the pier that will be used in my ROR observatory.  It's an Altair Astro metal pier which requires 4 x M12 bolts to secure it.  I have already put on a 1 tonne concrete block to bolt the pier to.  My plan is to drill 4 holes in this block and glue in 4 x lengths of stainless steel rod.  What resin/glue would people recommend for doing this?

Cheers 

[doublevodka]

You could use something like this? https://www.screwfix.com/p/rawlplug-rawlbolts-m12-x-140mm-5-pack/57310

Although someone will be along shortly to tell you you should have set them into the block  

 

[wulfrun]

If you must glue it in, use an epoxy such as standard araldite (don't use the quick-setting versions, they are weaker). It would be wise to use threaded rod and not plain, for much-increased surface area. However, the rawl-bolts suggested above by @doublevodka are a far better solution - less faff and far more secure.

Edited September 20, 2023 by wulfrun
clarity

[Swoop1]

Not used them myself but I have heard good reports about this type of resin/ epoxy capsule

[John_D]

22 minutes ago, wulfrun said:

If you must glue it in, use an epoxy such as standard araldite (don't use the quick-setting versions, they are weaker). It would be wise to use threaded rod and not plain, for much-increased surface area. However, the rawl-bolts suggested above by @doublevodka are a far better solution - less faff and far more secure.

I've used this sort of thing quite successfully as well - https://www.screwfix.com/p/dewalt-blue-tip-2-flange-thread-cutting-screwbolts-10mm-x-120mm-25-pack/323ht

If you do use them then make sure you vacuum the dust out the hole after drilling otherwise the bolts might not go all the way in ( don't ask how I know that! ). I used a socket set to drive them in rather than an impact wrench.

[david_taurus83]

The rawlbolts will be fine as long as the concrete is fully cured. It will take some serious lateral force to the pier to pull them up if you were worried about that happening. 

[SlimPaling]

You will almost certainly need to have access to a decent hammer drill to make the holes in the concrete.

An ordinary drill ( even with a top quality masonry bit) will simply bounce off any stones in the concrete and go badly off course.

Rawlbolts are fine.

 

[Starflyer]

I've used these three times, solid as a rock.

https://www.ebay.co.uk/itm/182235490751

I wouldn't risk splitting a block of concrete by using rawl bolts.

[M40]

Having used both, the chemical fixings work very well in crumbling powdery concrete but if your concrete base is sound enough, the rawlbolt type advised by doublevodka will work perfectly. My choice would be the rawlbolt type but with a 12mm stud, this way you can stick a second nut on the stud and then just cut the stud to suit. I cant see the concrete breaking unless you are drilling close to the edge. Hope it helps.

[fozzybear]

we use these at work https://www.spitpaslode.fr/en/Mechanical-fixings/Wedge-anchor/FIX-Z-XTREM_pFR_153469sharp0.htm#/reco-loads

also https://www.spitpaslode.fr/en/Mechanical-fixings/Wedge-anchor/FIX3_pFR_89132sharp0.htm

maybe avail in the UK

 

Edited September 20, 2023 by fozzybear
added text

[ollypenrice]

Having once split a slab with expansion bolts, I use only builder's epoxy of whatever make they have in the store. I drill a snug hole with a big hammer drill, squirt in the two-pack epoxy and tap in the threaded bar with a hammer. I don't hit the threaded bar, only a nut and locknut threaded onto the top of it.  This method has never failed for pier fixings and we have 8 piers here.

Olly

[WolfieGlos]

At work we use Hilti but they will probably be too expensive for this kind of fixing. But rawlplug or another will be fine.

Resin or knock ins would be ok, we use M12 and up for structures so 4x M12 would be fine for a pier. Just allow the concrete to cure if post-fixing them, and keep the anchors away from the edge to avoid cracking and get better pullout values. As a rule of thumb we say no less than 100mm for M20, preferably 125, so would suggest 75mm for M12.

[CraigT82]

Presumably the pier is going in the middle of your 1000kg block of concrete, so I wouldn’t worry too much about splitting it with the expansion bolts.  If you don’t have an SDS drill I’d heartily recommend the Titan one from screwfix, it’s a beast and makes drilling good holes in concrete a piece of cake. Can be used for all sorts too with the chisel/point bits and the rotostop function 

[Peter Drew]

I've always managed with a standard B&D drill with hammer option.  I just drill a small pilot hole and then open it up with larger bits to size.    🙂

[SlimPaling]

3 hours ago, Peter Drew said:

I've always managed with a standard B&D drill with hammer option.  I just drill a small pilot hole and then open it up with larger bits to size.    🙂

Well ... I tried my trusty B&D drill with hammer option and it did not cope when the bit hit to a stone in the concrete and it went way off line and it completely destroyed my masonry bit..

I quickly realized that my resulting 4 holes would not have lined up with the holes in the bottom of my pier ..... and I changed tack. ..... I got a "JCB SDS Plus Hammer drill" which went through my concrete like butter with all 4 holes in the correct place. The whole process took about 5 minutes :-)))

Mike

[John_D]

8 hours ago, CraigT82 said:

Presumably the pier is going in the middle of your 1000kg block of concrete, so I wouldn’t worry too much about splitting it with the expansion bolts.  If you don’t have an SDS drill I’d heartily recommend the Titan one from screwfix, it’s a beast and makes drilling good holes in concrete a piece of cake. Can be used for all sorts too with the chisel/point bits and the rotostop function 

+1 for the Titan drill. I've yet to find anything that stops it and the chisel bits are excellent for removing tiles.

[Peter Drew]

6 hours ago, SlimPaling said:

Well ... I tried my trusty B&D drill with hammer option and it did not cope when the bit hit to a stone in the concrete and it went way off line and it completely destroyed my masonry bit..

I quickly realized that my resulting 4 holes would not have lined up with the holes in the bottom of my pier ..... and I changed tack. ..... I got a "JCB SDS Plus Hammer drill" which went through my concrete like butter with all 4 holes in the correct place. The whole process took about 5 minutes :-)))

Mike

I would use an SDS if I had one.    🙂

[Rusted]

Tool hire should give you access to the proper kit.
No need to buy for a one-off job.
Said the man with two sheds full of tools. 

[900SL]

Expansion anchors can crack unreinforced concrete if near the edge

They also lose resistance to pull out over time due to concrete creep 

They are easy to install however. 

Resin such as Hilti HIT HY 100 is suitable for threaded rod.  Needs to be installed in strict accordance with Hilti recommendations and will be more of a faff.

MIStructE, CEng

[saac]

On 20/09/2023 at 10:07, michaelmorris said:

I'm about to install the pier that will be used in my ROR observatory.  It's an Altair Astro metal pier which requires 4 x M12 bolts to secure it.  I have already put on a 1 tonne concrete block to bolt the pier to.  My plan is to drill 4 holes in this block and glue in 4 x lengths of stainless steel rod.  What resin/glue would people recommend for doing this?

Cheers 

A few months ago I had to move my existing pier to accomodate my new Esprit 120 in order to get the height clearance needed; this involved extending the pier foundation and shifting the pier base a few cm.  To bolt the pier to the new location I used exactly the same method as I used with the original pier -  12 mm diameter studs fixed with resin.  Screwfix supplied both the studs and the resin. While I used studs (some left over from different project), threaded rod cut to the required size would work equally well.  If you can get a hold of an SDS drill and a new drill bit it will make short work of drilling the holes.  If you do use the resin, you need to make sure the holes are free from debris and dust - a blower is best but I got away with using a short flexible poly pipe.  Wear safety glasses when blowing the dust out , it's surprising how much is in there and how far it blows out!  Follow the instructions on the resin container, use a large caulking gun and your bolts are good to go.  The resin sets in minutes but I think I let them rest for a few hours before properly tightening down the pier - the process is pretty straightforward really. 

https://www.screwfix.com/p/rawlplug-r-kem-ii-styrene-free-polyester-resin-300ml/32863?tc=MC9&gclid=Cj0KCQjw9rSoBhCiARIsAFOiplkF-TewnRlIckFS3dGPMgavAB9sp7QptIaggfjFAlLzIGDjvF5CPGIaAnxdEALw_wcB&gclsrc=aw.ds

https://www.screwfix.com/p/rawlplug-studs-bzp-m12-x-160mm-10-pack/3806f

 

Jim 

Edited September 22, 2023 by saac