Mounting tools to concrete?

[Hitch]

Each and every one has its merits...

Cheap and cheerfull, and fast, in solid substrates, use thrubolts.
Cheap and cheerful, fast, brick etc, use shield anchors.
Good solid, no expense spared, chemical resins, work in just about anything. (ideal for cob/natural stone)


As said, theres loads of different fixings available, the screwfix catalogue gives a good brief description of theire useage.
Resins are excellent, providing they are used properly. I did a brief page for the UHM website sometime ago on resin, for anyone not familiar with the stuff.

 

[Robotstar5]

Used to use chemical fixings for large industrial robots, they would swing 100Kg round upto 2 metres a second day in day out without coming loose.
Got a similar system at work with sleeve anchors, manages to rock the fixings and work itself loose - have to tighten every 3 months.

 

[Weldingartisan]

It all depends on the quality of the concrete and the position of the fixings. Expansion type fixings put high compressive loads in the slab. From memory an M16 expansion bolt should be no less than 200mm from the edge of a beam or slab and a minimum of 150mm centre to centre of fixing. Chemical anchors have no such restrictions and perform much better in weaker slabs. Installing baseplates near the edge of slabs - as in mezz floors - I would go for chemical resin every time, especially as slabs quite often mysteriously thin down near the edges on some industrial developments.........W/A

 

[Pete.]

Fine theory but the reality is that you can put a 20mm shield anchor 3 inches from the edge of a slab with no ill-effects, unless you crack the edge whilst drilling the hole. Many beams & columns I fix into are barely 200mm wide. To crack a slab 8" from the egde would need several dozen tonnes of expanding pressure.

 

[Hitch]

Ever tried putting a row of half a dozen in line?

Crack

 

[Pete.]

Yes, actually. It's how we mount some of our machines. It's theoretically possible that a row of anchors might crack concrete but you'd have to drill the holes so close together you're practically severing the concrete anyway. The percussion of the drill will do all the damage beforehand. I use these fixings near the edge of brick walls and sometimes they crack but rarely - and concrete is many times stronger. I do this for a living:

 

[peter99]

Chemical / resin every time for vibration or near edge / tricky fixings. decent stuff cures in 2 or 3 hours to useable strength. You MUST blow out the holes though, either with a decent hand pump or pref a compressor to remove all dust (or resin sticks to that not the drilled hole wall) and not good for damp bases etc.

 

[Welderpaul]

Concrete bursting?

 

[Pete.]

Concrete bursting?

Yeah two triple-head bursters running 2800bar. Total pressure of 523tons across the hole to crack that block.

 

[Welderpaul]

Looks a fairly large lump in comparison to the mini digger at the back of the photo. And a handy gulley for the drilling water to disappear down.
What was it for?

 

[Pete.]

60 tons of London's finest

It WAS holding up the arch fronts at St Thomas St - rail approach to London Bridge Station. We chopped out the arches behind but the fronts had to remain. They battered one of them for 3 days with a digger before getting stopped for excessive noise with only half of it done.

After we attacked this one with the burster it fell apart in a few hours just using that little 5-tonner.

 

[Weldingartisan]

Fine theory but the reality is that you can put a 20mm shield anchor 3 inches from the edge of a slab with no ill-effects, unless you crack the edge whilst drilling the hole. Many beams & columns I fix into are barely 200mm wide. To crack a slab 8" from the egde would need several dozen tonnes of expanding pressure.

No, not a theory but manufacturers recommendations:
Ramset Dynaset drop in anchors:
M10 - 100mm centre spacing; 135mm edge distance
M12 - 125mm centre spacing; 175mm edge distance
M16 - 165mm centre spacing; 230mm edge distance
M20 - 205mm centre spacing; 285mm edge distance
These figures obviously have a safety factor built in and are to achieve the maximum strength of the fixing, which is probably rarely required. but ignore them at your peril! W/A

 

[Hitch]

A lot depends on the quality of the concrete aswell. We put a row of 6 or 7 shield anchors in a line on what seemed to be a good solid wall. Half way through tightening up it started to crack.

 

[Weldingartisan]

Chemical / resin every time for vibration or near edge / tricky fixings. decent stuff cures in 2 or 3 hours to useable strength. You MUST blow out the holes though, either with a decent hand pump or pref a compressor to remove all dust (or resin sticks to that not the drilled hole wall) and not good for damp bases etc.

I was about to say that all the resins I have used have stated that dampness is no problem. So I've just pulled a Fischer F-Bond styrene free cartridge off the shelf to check and it does not mention dry, damp or whatever - so now I'm confused. Maybe it's the 'styrene free' tag thats changed it. W/A

 

[Pete.]

For structures that won't hold a shield-fixing we use Hilti Hit150 resin. This is usually very soft or fragile bricks like gaults and stocks. The Hit150 has a reasonably fast curing time 20 mins to an hour or two depending on conditions) and is easy to work with. You gotta keep the holes free of dust, damp isn't so much of a problem so long as it's not swimming in water. We blow em out with a blowpipe then set the resin.

WA: Those red-head-style Ramset anchors impart a lot more load across the hole than the shield-type ones, because the body is stiffer and the wedge is punched-in rhather than the thin-walled shield-type ones with their drawn-in wedge. Having said that, their reccomendations are far beyond what's necessary in practice. They are used quite commonly in holding balustrades etc where most are fixed near an edge or on an upstand. They'll commonly be very close to an edge of a slab. Any concrete that can be cracked with such an anchor isn't fit for fixing anything to it anywhere at all.