Weld reinforcing mesh for concrete?

[Dave H.]

Does the team think....

I'm planning the construction of Shed 2.1 - about 12' x 10', to take Heavy Objects (i.e. a lathe, milling machine if I can pick one up within budget[1]) and have settled (thanks to pavingexpert.com) on a pad 13' x 11' of 6" or 8" concrete with 2 layers (at top and bottom with 2" concrete cover, stopping 4" from edges) of A142 steel reinforcing mesh - rather than wire-tie the sheets where they overlap by more than a foot, is there any reason I can't overlap a bit less (4"?) and weld the rods together with the trusty buzzbox? That way I'd have enough left over to run mesh (also welded to the main reinforcement) into the ramp for Heavy Object access.

Any useful hints and tips from those who knows?

Thanks, Dave H.

[The Natural Philosopher]

don't see why not, if your welding is good enough to maintain integrity.

The purpose of the stuff is to hold tensile loads across the pad.

[NT]

almost no overlap should be fine if youre welding.

NT

[Dave H.]

Thanks gents, I couldn't see any reason not to!

I'm assuming that the mesh is boring mild steel, ordinary rutile electrodes (rods) should do - is there any point painting the mesh (perhaps a zinc rust inhibitor / primer) before laying the concrete on it, or is that gilding the lily? There'll be a DPM between the sand blinding and the slab (on 2" of polystyrene foam, warm workshop!) to prevent water ingress, and other than coolant spills the top won't be getting wet (I hope...)

I was thinking that once fully cured, it might be worth a layer of epoxy floor paint to seal the slab from oil etc. contamination (if pocket allows after all the other work!)

Dave H.

[JimK]

no don't bother painting but leave it clean or *better* rusty - as the concrete will grip it better and seal it all against further corrosion.. Cheers JimK

[zaax]

There is always that garage floor sealer you see advertised during races and auto shows.

[Rick Hughes]

If you want belt & braces approach having joined mesh run a 1/2" rebar at 90 degrees to the overlap ...across the width of mesh ... just tie it to mesh with cable ties. That is what I did on similar job.

Remember you need at least 50mm of covering of steel so space up the bottom layer, and make sure top layer is at least 50mm down ..... it gets quite thick once you start overlapping.

Importantly ... you need to make sure you use a good vibration poke to consolidate the concrete around the steel - don't skimp on this, and if you are self mixing avoid going too wet on mix or the water will separate out.

[Dave Osborne]

Definitely. Not just for oil contamination, but because sealing the surface of the concrete will prevent dust being raised every time you sweep the floor.

Get rid of any/all laitance (with concrete etching fluid or dilute brick acid) before painting.

Go for polyurethane if you can't run to epoxy. Anything's better than nothing.

[Dave Osborne]

forgot to add this link:

I don't know if this (Concrete dustproofer and hardener) is any good, but it's certainly cheap.

small piece of advice. There's always a temptation to pour paint onto the floor and then spread it out, rather than pouring it into a tray and applying by roller. Don't pour directly onto the floor. You will end up using three or four times as much as you need.

[Dave H.]

Took a look, useful for near-zero budgets (like mine), but concerned by the "Note: Should not be overcoated with floor coatings"

I'd be concerned that that would mean I couldn't apply epoxy / whatever further down the line...

Points re etching and roller for paint noted, thanks gents.

Dave H.