Column Base Grouting

[howardm]

Hi,
Anybody know about epoxy grouting for my column bases.?

Not looking to skimp on this item, what is the best/easiest to use.
By calculation, it looks like I need 1.6 litres per base, 10 bases to do.

Would it be OK with the face galvanised, or should it be ground off.?

thanks
Howard

 

[Welderpaul]

Use Fosroc Conbextra or 5 Star non shrink cementitious grout. Doesn't need to be epoxy.
Don't grind the galv off the baseplates.

Knock up a little shutter say 50mm away from the edge of the baseplate and tip the grout in (Water-like consistency) until it is 10mm or so up from the bottom face of the baseplate - refill as ness if it settles.

 

[Pete.]

5 star non-shrink grout is wicked, about 20 quid a bag from Jewson. Really workable to whatever consistency you require and dries hard as rock.

 

[Shox Dr]

Cement and kiln sand is just as good.

 

[Hitch]

We used Kwixset on the last few jobs that needed it....

Get everything ready before you start mixing anything!

The 2 that Paul mentioned seem to be the ones everyone asks for though.

 

[howardm]

Thanks for the info folks.
I can continue with confidence now.

Howard

 

[feen]

Try a little sand around the outside of your shutter just to seal it. You'd be surprised how much can leak out.

JF

 

[howardm]

OK, next question men.
Levelling the structure.
I was toying with the idea of putting thin nuts on the resin anchor bolts to stand the
baseplates on. Then I could make fine adjustments to the heights on the locknuts.
Obviously the nuts are there for ever after grouting.
Am I thinking too hard.?
The raft was actually power floated anyway, so maybe some 20 shims would be sufficient.?
Any input much appreciated

thanks
Howard

 

[Pete.]

Steel wedges is what the steel erectors use.

 

[Welderpaul]

Nah, jacking nuts take too long.
Sweep the bases, cut some steel shims say 100 x 100mm, varying thicknesses, 12mm, 10mm, 6mm, 2mm, stack them in the middle of the bases then level them all in to underside of baseplate datum with a laser or dumpy level. Stand your columns on, do the nuts up by hand then tighten as necessary to pull the column plumb. The shims being in the centre acts like a pivot.
Once all your beams are in and the columns can't pull around then dog all the nuts up with either an impact wrench or a podger c/w scaffold tube on the end.
Wedges are usually used to shift the bottoms of the columns over when lining and levelling. A bit rough **** too.
You're post-fixing which makes life very hard as opposed to cast-in HD bolts.

Structurally, not a good idea to have the weight transferred onto the bolts. The bolts are usually just to locate the thing, and in some cases to prevent uplift of the structure. I know of a tall building in the middle of nowhere in Penrith with M36 holding down bolts 1200mm long, in clusters of 8 for each column, with U bends on the end to tie them into the reinforcement. They took some setting out to make sure they were right!

 

[Hitch]

We supply both steel wedges, and 100x100 packers, in fair quantities. Usually have a pallet of each for every new job.

Exactly as Paul said, shims under the centre, then pull bolts up as required to get straight. Beat wedges in sideways to move the column over to keep the centres of whatever correct. If the baseplates are screeded over or whatever after, it doesn't matter.

 

[howardm]

Ok guys
I'll use shims/wedges.
This structure is heavier than I imagined.!

Should have broken it down to more bolted parts Paul.!


Howard

 

[howardm]

Speaking of screeds.

Is there anything particularly suitable for a workshop floor (light fabrication)
I would like it level enough to use as a datum.

The architect has specified 75mm insulation with 150mm screed over.
Is this stable enough for fabbing, would the insulation sag.?
Any particular kind of insulation.?

I should ask my architect but he's a wonker, knows less than me.
He 's good at sending bills bigger than his quotes and adding hours up.

thx
Howard

 

[Pete.]

Why you putting screed on a powerfloated floor?

 

[Welderpaul]

The problem with a screed on rigid insulation that it is prone to cracking. 150mm of screed sounds very much overkill. The otherway round - 150mm insulation/75mm screed sounds more like a standard spec.
TBH, you would struggle to get any form of screed level enough to be a datum for fab work (Depends on how accurate you need things to be of course).
We've managed to crack a 250mm thick mesh reinforced concrete slab in 3 places at our place.

I would have powerfloated a reinforced concrete slab and left it at that. You would be best with some sort of self-levelling screed but it needs to be fairly thick to stop it breaking up. Self levelling screed doesnt like being laid very thick though. You'd be best speaking to the technical department of a couple of companies - tell them what you want it to do and they will specify their most suitable product.

 

[clift_d]

150mm sounds more like the thickness for a reinforced in-situ concrete floor than a screed - most floating screeds are usually only 75mm. You need to make sure your insulation is load rated for the kind of traffic the floor is going to take. Also, if you are pouring on top of insulation it's common practice to put a polythene layer over the insulation first with upstands up at the edges - it stops loss of the more 'fluid' concrete down the gaps between the insulation boards which I understand can lead to weak points in your finished floor.

The best people to speak to would be Flowcrete - if you tell them what kind of floor you want i.e. what you want to be able to do on it, then they should be able to help you with the right specification. They should also be able to recommend some contractors near you who can price/ undertake the work.

 

[howardm]

Thanks for the tips guys.

I will try Flowcrete, the problem will then be to find a contractor to do this small job in the Aberdeen "oil bubble"

thx
Howard