View Full Version : Working out how much concrete bags needed

Hi,

Quick question.

How do I work out how many bags of concrete I would need to mix to fill a certain area up?

Many thanks.

Matthew5664

16-03-06, 22:00

How good a mix do you want? are you using lagre or small stones?? to fill a square meter you looking at about 1/4 ton stones and 3 25kg bag of dust thats a good 1:3 mix. This for a bed for a tank I'm guessing

to fill a square meter you looking at about 1/4 ton stones and 3 25kg bag of dust thats a good 1:3 mix.

Surely depth is required, a square meter is of no good to any builder, cubic volume is required.

3 dimensional....

Matt

Matthew5664

17-03-06, 08:47

Sorry it was late and I'd had some wine! meter cubed.

Hi,

This topic is spawned from one of my other threads (http://www.ultimatereef.net/forums/showthread.php?t=176793) concerning how to support existing flooring for my new fantasy tank. The kind advise from fire999 suggests creating a frame from brick or blocks and filling that up with a mild mix concrete as far as 3" from the top. The remaining area will be filled (after initial drying time) by sand/cement screed.

The area I am looking at tackling will more than likely be 8ft by 5ft, and I reckon there is a standard 2ft space under the floorboards.

By my calculations, that is 80 cubic foot which should translate to 2.265347737 cubic meters. So, this should translate to just over half a ton of stones and around 7 bags of 25kg cement.

Just for clarifications, are the stones a necessary makeup of the base cement?

I appreciate the responses.

Cheers :)

Hi,

This topic is spawned from one of my other threads (http://www.ultimatereef.net/forums/showthread.php?t=176793) concerning how to support existing flooring for my new fantasy tank. The kind advise from fire999 suggests creating a frame from brick or blocks and filling that up with a mild mix concrete as far as 3" from the top. The remaining area will be filled (after initial drying time) by sand/cement screed.

The area I am looking at tackling will more than likely be 8ft by 5ft, and I reckon there is a standard 2ft space under the floorboards.

By my calculations, that is 80 cubic foot which should translate to 2.265347737 cubic meters. So, this should translate to just over half a ton of stones and around 7 bags of 25kg cement.

Just for clarifications, are the stones a necessary makeup of the base cement?

I appreciate the responses.

Cheers :)

2.2 cube of concrete equates to just about 4 tonne of ballast plus your cement. I'd buy it in bulk from a builders merchant, ask for tonne bags, they'll deliver to your door and park it on your drive.

Depending on your situation with the builders merchant, for example do you have an account etc, it'll cost something like £30.00 a tonne plus vat for the ballast and the cement'll work out at something £3.50 a bag, 7 isn't enough by a long way. At 4:1 you need to allow for 40 bags plus.....

Matt

Just called one of the local places up, and for 4 tons of ballast and 40 bags of cement they r quoting around £280 (incl vat and delivery). Not too bad.

Cheers, mate.

YorkshireMarine

17-03-06, 11:04

a good way to work it is 10 bags of cement to a ton of ballast. and mix it 4:1 ratio normally 12 shovels of ballast and 3 cement is a full mix in those orange bell mixers.

Glenn@home

17-03-06, 11:40

Yes you need the stones it increase the strength of the mix, the cement and sand acts to bind it all together iirc.

Re purchase you may find readymix will be in the same ballpark, possibly a little cheaper, i cant remember the actual cost last time i bought a couple of yards.

For cost you also need to figure in the effort of mixing yourself. It can be done by hand if you're old and are always saying things like 'this is how we used to do it in the old days' but its bloody hard work and will take a lot of time.

A mixer will help and hiring will cost, but having it delivered and just barrowing it is the easiest option.

It also has the bonus of giving you a guranteed mix (well a good chance anyway).

JMHO

Glenn

Rutland Gizz

17-03-06, 13:08

FWI, we buy in readymix at £65 per cubic metre, +VAT. (£390 per 6 metre cube lorry load). It may be more than that if you only take a part-load. You will need to make sure your shuttering is strong enough though!

Also, 3 inches of screed is a lot, I'd look at more like 1 inch skimmed over the concrete.

You need approximately two tonnes of ballast for 1 cubic metre.

For mass fill concrete you need about 250kg cement per cubic metre, for structural concrete (eg ground beams, lintels, suspended floor slabs etc) you should go for about 300 - 350 kgs per cubic metre.

hth

Paul

watsonanthony

02-06-09, 21:20

Hi,

Quick question.

How do I work out how many bags of concrete I would need to mix to fill a certain area up?

Many thanks.18 suare meters by 4 inches thanks:thumbsup:

watsonanthony

02-06-09, 21:35

how much concrete mix do i need for 18 square meters by 3 inches

18m2 X 75mm(0.075m)=1.35m3:)

What Pavlo said. He does it every day!

if you want to see a chart/graph look on wickes site or save time and refer to my first sentence.

The question was asked over 3 years ago :)

Where do people dig these old posts up from :D

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