Correct concrete mix?

[legepe]

Hi all,
Dug two footings 18"w x 12"d x 3.8m each. for sleeper walls to support 5x2 joists for new floating floor.
Got my hands on a cement mixer and ready to go... I was going to use 20mm aggregate with a mix of 4 aggregate x 2 sharp sand x 1 cement for the footings... is this right, or should I add 10mm aggregate as well? and what would be the correct water volume to use?
Thanks
legepe

 

[stuart45]

Use 6/1 all in ballast/OPC. Water depends on how wet the ballast is.

 

[legepe]

Sorry Im a complete beginner with this..! what is opc? and i take it that the ballast is ready mixed.. so all i do is add one part cement? also, can you give me some idea of what texture of the mixed content should be when water is added ..? Ive read that if this is not right then cracking can occur

 

[stuart45]

OPC is ordinary portland cement.
General rule of thumb for concrete/mortar etc is to have the minimum amount of water to make it workable.

 

[legepe]

Ok thanks for that stuart45, I will not make it too wet then...

 

[legepe]

At a guess so far I will have from the base of foundation around 18" to bottom of 5x2 joist.. any suggestions on how to build the walls.. what blocks/bricks to use.. i want to keep it simple... but obviously effective enough to have good air flow etc...

 

[stuart45]

Use brickwork laid in a Honeycomb bond.
https://www.google.co.uk/search?q=h...QsAQIKA&biw=1366&bih=662#imgrc=I6kPjDfxtmassM: