C25 concrete mix ratios

[WWilts]

Small amount of C25 concrete to be mixed for foundations. (2800mm double skin masonry wall, side of lean to).

 

Is the following correct?

 

Ratio of C25 concrete grade is 1:1:2, in which one part is Portland cement mixed with 1 part of fine aggregate/ sand and 2 part of coarse aggregate with required quantity of water to reach compressive strength 25 Newton per square millimetre (N/mm2) or 25MPa at 28 days curing

[Russell griffiths]

Are you thinking you are going to buy sand and aggregate separately then buy cement. 
just buy concrete ballest already mixed together and add cement and water. 
5 ballest 1cement will be perfectly adequate for a footing mix. 
can you not just get a couple of metres of readymix. 

[JohnMo]

nominal mix, ratio of C25 concrete grade is 1:1:2, in which one part is Portland cement mixed with 1 part of fine aggregate/ sand and 2 part of coarse aggregate with required quantity of water

[Mr Punter]

17 minutes ago, JohnMo said:

nominal mix, ratio of C25 concrete grade is 1:1:2, in which one part is Portland cement mixed with 1 part of fine aggregate/ sand and 2 part of coarse aggregate with required quantity of water

 

That sounds really strong.  If using all-in ballast that would be 1:3.  Often for general purpose concrete I mix 1:6 cement:ballast.