Concrete Calculations

charlotte_rose

Hi, we need 3.55 cu metres of c30 or c40 concrete for footings.

For a comparison, any idea how many 25kg or bulk bags of sand, cement, ballast etc are required for 3.55cu metres?

Portly_Pig

1 cubic metre weighs 1.4 tonne so you need 4.97 tonnes of concrete. Minus the water cause that's ready mix.

ValHaller

Would buy concreting ballast as 4m^3 bulk delivered rather than as bags - you would need about 200 and it is an expensive way to buy.

charlotte_rose

ValHaller wrote: »

Would buy concreting ballast as 4m^3 bulk delivered rather than as bags - you would need about 200 and it is an expensive way to buy.

as an estimate would 4 x bulk bags plus cement be around target? I think it comes in around £300

we have had a quote of readymix of £468.

Portly_Pig

charlotte_rose wrote: »

as an estimate would 4 x bulk bags plus cement be around target? I think it comes in around £300

we have had a quote of readymix of £468.

Plus your mixer hire and time.

You know what you're getting with ready mix.

charlotte_rose

is it feasible to machine mix 3.55 cu m?

ceredigion

charlotte_rose wrote: »

as an estimate would 4 x bulk bags plus cement be around target? I think it comes in around £300

we have had a quote of readymix of £468.

know. an estimate = 7xbulk bags+35 bags of cement

Furts

Why does the mix have to be C30 or C40? These are two different mixes. Is the reason because you have reinforcing bars in your concrete, or contaminated ground, or sulphates...?

I would not entertain mixing the quantity by hand. It is hard work and time consuming even if you have a decent site mixer. The weight in a dry state will be approx 8 tonnes- this is a lot more than given on a previous post!

The ready mixed companies buy their sand, aggregate and cement in vast quantities - you will not be able to match these prices buying individual quantities.

Do not buy all in ballast or hoggin if you are using the mix for structural purposes or for paths or drives.

I strongly suggest you shop around for a ready mix price. Do not get caught with part load charges who ever you choose to supply. The big suppliers can catch out the unwary on this. Consider a conveyor lorry or extended shute or integral pump if appropriate.

Finally, discuss your intended use thoroughly with the supplier. Include additives, admixes. consistency, water cement ratio...

Portly_Pig

charlotte_rose wrote: »

is it feasible to machine mix 3.55 cu m?

It's 40 mixes.

charlotte_rose

Portly_Pig wrote: »

Plus your mixer hire and time.

You know what you're getting with ready mix.

aye, the only problem is access over restored tiled floors.

we have to get everything in and out of the flat to and from the garden. I heard readymix can be messy.

ian103

don't know where you are in the country but have a look at this web site for ideas
http://www.accumix.co.uk/