Mixing concrete

[westminster]

Can anybody help with a few queries I have please:

I need to make a new terrase (22m X 4m) It will have a small foundation running along its length to support an oak post roof for shade type structure.

How deep should the slab and foundation be?
Should I use expansion joints anywhere?
What sand to cement mix should I use?

Thanks for any help.

 

[RedHerring2]

150mm compacted hardcore then 100mm concrete.

You probably won't get ballast so use 1:2:4 cement: sand: gravel (about 20mm).

Expansion joints about every 3 metres, that will leave you about 1.2 m³ each day to mix and lay. Alternatively use readymix. (22X4X.1 =8.8 Metres³)

Joint d'expansion, I think the expansion joints are called but they're very different to ours.
Got to rush off now but when I get back I'll knock up a sketch.

BTW Terrasse, in France are classed as habitable space therfore taxable.

 

[RedHerring2]

Sorry, Joint de Dilitation is the expansion joint.
It's a hollow plastic extrusion, about 5 metres long shaped a bit like this:
View media item 30231in cross section.
It comes in 40 or 80mm deep options. It doesn't bend very easy in the vertical plane. You'll need 80mm depth. Obviously, pointy end upwards.
So if you're planning on a fall in the terrasse, in two different planes you'll have fun. I managed it by clamping it in place with screws fixed to a sizeable piece of timber shuttering, but I had a fall into the centre and along the centre of the terrasse. But the screws didn't penetrate the expansion joint, just above top and bottom to clamp it. It's not easy 'cos the bottom is about 50mm wider than the top. And you'll neeed to be able to remove the piece of timber, with the screws after the concrete has cured, leaving the expansion joint in place.

On the sizes of sections, you could go to 4 metre wide sections (about 1.6 M³) each time. It depends on your mixing and laying ability.

We did about 6 sections over 6 days, (me and the OH) 'cos we could only do about 1m³ each time. But I had had about 28 tonne of sand and the same of gravel delivered some time ago. We were getting towards the end of it so it was about a 4 metre walk from the gravel to the mixer, then the same for the sand. Then about a 25 meter hike, through the house, with the barrow to the terrasse.

Pictures of terrasse here, but there are more and better pictures on the previous post.
http://www.diynot.com/forums/viewtopic.php?t=237971

 

[RedHerring2]

If you go down the readymix option, they may ask you if you want the "trevalator". I forget the French term for it, but it's a mechanised conveyor belt which is used as an extension to the chute. You don't have to have it and it costs extra. Although it is probably carried on all the big cement wagons.
If you can, specify the amount of 'slump'. When I did my floor it was so wet I couldn't tell what was concrete and what was water.

 

[dipwing]

When we had our 1200mm footings filled (9m x 5m approx) the mixer used had a conveyor. Very handy for the long part and to get around the back of the house.
The driver/operator was pretty clever and made a wedge half way down using a dryer mix (effectively splitting the footings in two) and then conveyored the concrete in two stages/sections. This meant we did'nt end up raking it around the whole trench.

The concrete firms local to me only really use the conveyor in larger drops but you should be ok.

We were advised to use Gen 3 concrete for footings.

Good luck.