What type of concrete/cement?

[Anna1984]

I am going to place a large order at Bauhaus and have the items delivered. I am also going to cast about 10 plinths of approximately 120 cm.

Now I am looking for concrete/cement for the casting, preferably available at Bauhaus (since I will have it delivered) and that only needs to be mixed with water. Which product should I choose?

 

[SC Aero]

Rough concrete
http://www.bauhaus.se/grovbetong.html#full-description
You get about 10 liters from a 20kg sack.......just start calculating

Don't you want a bunch of rebar as well?

 

[Anna1984]

Concrete mix
[link]
You'll get about 10 Liters from a 20kg bag.......just start calculating

Aren't you also going to need some reinforcing bars?

So you only need to mix that with water and nothing else?

I am going to cast pipes with a diameter of 15 cm. How many bags will it take for a 120 cm pipe?

Well, I am going to cast foundation blocks to place post shoes for the deck. Do I need reinforcing bars then?

 

[Mikael_L]

Do you only need to mix that with water and nothing else?

Yep, and be quite careful with the amount of water; it can go wrong quickly if you add just a bit too much water.

I am going to cast a pipe with a diameter of 15 cm. How many bags will it take for a pipe that is 120 cm?

A pipe Ø15cm x120cm has a volume of V= (1.5/2)^2*pi*12 dm3 = 0.75*0.75*3.14*12 = 21.2 dm3 = 21.2 liters.
So, it takes just over 2 bags per casting pipe.

Well, I'm going to cast footings to put post shoes in for the patio. Do I need rebar for that?

Yes, preferably. Pre-made footings often lack rebar, and they seem to hold up anyway. But slipping in a couple of pieces of 8 or 10mm rebar isn't that hard, and then you know it will hold up. Yes, the rebar can be quite heavy to push in after the concrete is in place, better to have them in place before you fill the pipe.

 

[Anna1984]

A pipe with Ø15cm x120cm has a volume of V= (1.5/2)^2*pi*12 dm3 = 0.75*0.75*3.14*12 = 21.2 dm3 = 21.2 liters.
That is, it takes just over 2 bags per forming tube.

Thanks for that! I wouldn't have managed it myself .

 

[Mikael_L]

I probably presented it as more difficult than it actually is.
The formula is the usual - radius times radius times pi, which gives the diameter, and then times the height of the tube, and it's done.
If you calculate with dm all the time, you get the answer in liters.

But instead of just writing "2 bags," I think it's a nice touch here on the forum to also present how you arrive at things.