Ratio for concrete (foundations)

[paulweller84]

Hi,

I am going to be mixing concrete (using a mixer) which will be used for trench fill foundations. Building control have advised GEN1 or GEN2 which means nothing to me. Can anyone advise on a suitable ratio please, and also explain what type of aggregate is best.

Thanks

 

[HERTS P&D]

Get it delivered, it will save your back.

Andy

 

[paulweller84]

No point. It’s being poured in sections

 

[^woody^]

1:5 or 1:6

But foundation strength is not just about the ratio, there are several other factors.

Mixing DIY can not guarantee any particular strength, nor even guarantee consistent or identical batch strength - which is what is required for concrete in bays.

 

[paulweller84]

1:5 or 1:6

Sorry, what does this refer to? Is this cement:aggregate? If so, what sort of aggregate am I looking for?

I also need to mix up concrete for fence posts and a hot tub base, if you can provide any guidance on those. Same ratio? Or not?

thanks

 

[noseall]

Sorry, what does this refer to? Is this cement:aggregate? If so, what sort of aggregate am I looking for?

1:5 or 1:6 refers to one part cement to 5/6 parts ballast.

Ballast is what you would buy for in bulk bags from builders merchants. Ballast is made up of a ratio of 4 parts 20mm gravel to 2 parts sharp (concrete or grit) sand. You can buy these items separately if you wish but why complicate things.

EDIT: Don't forget to add water.