Concrete slab reinforcing

[atregent]

I'm about to lay a concrete slab for my garden shed, 3100 x 2280 x 100, and was wondering what to do about reinforcing it.

I have an old chain link/cyclone wire gate that is about the right size for the hole, made of 1" gal tubing with the mesh. Would it be doable to use that instead of standard reo?

Or do not really need to worry about reo for a slab that size on sandy soil?

[Bleedin Thumb]

You don't need reo for a garden shed that size, I wouldn't bother anyway.
And if you wanted to use reo, cyclone wire is NOT the way to go.

Reinforcing a slab has some hard and fast rules about placement.

You need at least 50mm coverage around the edges, from control joints and 50mm over the top and bottom surfaces.

By chucking in an old gate you may find that you will not achieve that.
If your gate pipe is 25mm Plus 50mm top and bottom = 125mm slab required.

My phylosophy would be do it right or don't do it especially as in this case you dont need the reo.

Edit just read the part about the sandy soil. You have to do adaquate subgrade preperation no matter what type of soil, sandy soil may need a bit more. If you haven't used fill then water, compact and line with plastic sheeting. If you have filled I would be using compacted road base.

[atregent]

I suspected that might be the case, but I thought it'd be worth asking. I'm all for doing things right.

Should I do anything with the base, or just lay some plastic and pour the concrete?

[rod1949]

For your long term benifit do it right. Place plastic sheeting on the ground first, this stops the soil from sucking all the water out of the wet concrete making it easier to work, then the reo mesh with the coverage as Bleedin Thumb has said.

When its touch dry cover it with plastic sheeting for as long as possible (min 7 days) to allow it to cure properly. The underside of the plastic will create its own condensation, but I would also keep it moist by squirting the hose under it every couple of days.

[Bleedin Thumb]

Should I do anything with the base, or just lay some plastic and pour the concrete?

Level it off really well, run a compactor over it if you have any doubts about the bearing capacity of the soil but you don't have to go overboard if you haven't used fill to build it up.
Check once you have your form boards up that you have uniform depth all over, run a straight edge over the boards and measure down, rake & stomp to adjust any minor impefections.
Line with plastic and Bobs your uncle.

I always order (at least) 0.2 of a cube extra because the concrete plants are not known for their generousity. So its also good to have a place prepared for the extra barrow or two you may have over, you know that path that you were going to extend etc.

[atregent]

My calculations tell me I'd need 0.7m3, I figured I'd order 0.75 (make it an even 3/4). But I guess it's better to have too much than not enough.

The site is at the end of the driveway, so the truck can back right up to it and pour directly into the formwork. If I over order, can I send the rest back? I don't really have anywhere else that I need concrete at the moment.

[atregent]

Just got off the phone to Boral, much more user friendly than I was expecting (yes, I'm a programmer...), got 0.8m3 ($207) arriving at 9am tomorrow.

Let the games begin!

[Bleedin Thumb]

Good luck! I don't much like concrete pours...the best part is when there over.

At only 0.1 of a cube over make sure you are not low anywhere. There is nothing worse than being short.

I just put that last bit in to stuff up tonights sleep .

[atregent]

Thanks for that Mr Thumb! I'll be spending the rest of the daylight hours making sure the site is spot on.

I remember back to my youth when I spent a summer with a concreter, awful backbreaking work it was. I can still see the convoy of trucks, would've been at least 10 of them, heading into the new estate we were doing the footpaths and driveways for, knowing that there's be no break until all the concrete was done...

[Bleedin Thumb]

At 17 yrs old my first job in construction was pouring slabs for high school buildings in Townsville - no such thing as a pump just overfilled barrows on rickety planks in temperatures that would make the concrete set in the barrow...ah those were the days....

[atregent]

Well, that's it then, concrete is now in place, very pleased with the job so far.

As luck would have it, 0.8m3 was the perfect amount, only a very small amount spilled over the forms. Perhaps I've missed my calling...

[pawnhead]

Pics or it didn't happen.

[atregent]

It really did happen!

[pawnhead]

OK, I believe you now. I like seeing pics of the product of other peoples sweat.

Whilst it's still green, you should put a small 10 mm rebate in the slab underneath where your door is going (if you know where it's going). It will stop any water running down the door from being blown underneath and ponding inside.

[atregent]

The instructional video on the shed web site says to do a 15mm rebate all round, 70mm wide. I'm assuming for that very reason.

As soon as the surface water is absorbed, I'll be troweling and edging (had to buy some new tools last night, bugger. and some gumboots...)

I'll take some better pics when it's a bit more finished