Do these aggregate quantities look right?

Loveworking1999

I'm planning 2 x concrete shed bases in the garden a total area of 17m2.  Was going to lay 10cm type 1, then 10cm concrete on top.  I think i need:
13.4 tonnes of Type 1 MOT
12 tonnes of ballast
80 x 25kg bags of cement (ratio of 5:1 ballast:cement)
Does that sound right?  Seems a lot to me??

kazwookie

I have no idea, but to shift that much material I would be looking to get a readymix type machine in!

victor2

Seems like way too much to me. Use one of the online calculators that many suppliers have to estimate what you need.

How are you going to get all that aggregate into the garden? You'll need a small army with wheelbarrows to shift that much - and a big hole to put it in!

timjim

I think that looks far to much. Have a look at https://www.pavingexpert.com/calcall according to that it 3.6 tons of type 1

EssexExile

17 square metres at 1/10 of a metre depth is 1.7 cubic metres, I'd guess around 1.7 tonnes. (O-level maths 1966).

grumbler

EssexExile said:

17 square metres at 1/10 of a metre depth is 1.7 cubic metres, I'd guess around 1.7 tonnes. (O-level maths 1966).

What about physics?

I see online 1.92 density for the Type 1 that makes the weight about 3.25 tonnes

EssexExile

grumbler said:

EssexExile said:

17 square metres at 1/10 of a metre depth is 1.7 cubic metres, I'd guess around 1.7 tonnes. (O-level maths 1966).

What about physics?

I see online 1.92 density for the Type 1 that makes the weight about 3.25 tonnes

I failed physics, obviously.

stuart45

You need 2 bags to make a cubic metre of concrete. 6/1  ballast/OPC is OK for a shed base. 

ceredigion

As a ruff rule of thumb, one dumpy bag of ballast will need five bags of cement and will make 0.5m3  when mixed.

longwalks1

Thanks all - no idea where I was going wrong but cheers for saving me a fair bit of cash, and embarrassment too! 

FreeBear

ceredigion said: As a ruff rule of thumb, one dumpy bag of ballast will need five bags of cement and will make 0.5m3  when mixed.

Used just four bags of cement to one dumpy bag when I did my shed base (minor diff there)... But.... Even an 8x6 base is bloody hard work when mixing by hand. For 17m², I would be considering ordering a ready-mix load. For the quantity the OP needs, a mini-mix should be plenty.