Amount Of Cement And Sand Needed

[Palustris]

Been asked and I have no idea. How much cement, 6 mm granite and sharp sand in a 2:1:1 mix would be needed to make about 1.5 cubic metres of concrete?
TIA

[Atheist]

I used to know. Best to google it. There are formulae there which could help you.

[fiction-factory]

Is the 2:1:1 mix to be by weight or volume.
If it's volume here's my attempt:
Divide 1.5 by 4 to get 0.375 cubic metres.
For cement you need 2 lots of that- ie 0.75 cubic metres.
For granite you need 1 lot- 0.375 cubic metres. Same for sharp sand.

[fiction-factory]

I'm no builder/ DIYer, but wouldn't you need water as well though? Should the ratio cover water too?

[RATTER15]

^^ No the mix ratio of concrete mix does not cover water as it would depend on the moisture content of the other ingredients and the purpose the concrete is being used.

[fiction-factory]

Okay, thanks. But the 1.5 cubic metres of concrete presumably includes some water so to answer the question we'd need to know the approx amount of water needed.

[KARL]

That is a ridiculously rich dry mix of 50% cement against 50% aggregate matter, but if that is what you want (for whatever reason) then go ahead, but I would not know what to expect over time (days, weeks, years).

[TonyV]

Ask at your local builders merchants but that is a very "strong" mix.

[TonyV]

And IMO will not work at sticking anything.

[The Builder]

Yes, that is an unusually strong mix. Maybe it's for dense concrete padstones (bearings for lintels or steels), or something like that.

Anyway, when doing this sort of calculation, the rule of thumb is to disregard the cement when considering volume. The cement worms its way in around the aggregates. In effect, taking up little room.

1.5 cu m is roughly 3000kg (3 tonnes)

So, 2000kg of 6mm chips : 1000kg sand : 1000 kg cement.

Wow, a tonne of cement in 1.5 cu m of concrete.
I honestly can't imagine anyone specifying that .

[Palustris]

Thanks.

[TonyV]

Yes Builder I would only go 4 : 1 : 1 that's 4 soft sand, 1 Sharp sand & 1 cement.