Morter Mix for Foundation Blocks?

[iDIY]

Hi Guys,

I am laying a few hundred 300mm foundation blocks in a couple of weeks. Could you give me advice on the best mix and which sand I should use please?

 

[nickjb]

Soft, builders sand mixed 3:1 below ground or 4:1 above ground but below dpc. Splash of plasticiser. That's my understanding but I'm a DIYer.

 

[DIYer Damo]

Soft, builders sand mixed 3:1 below ground or 4:1 above ground but below dpc. Splash of plasticiser. That's my understanding but I'm a DIYer.

I second this. 3:1 below ground protects mortar against frost damage as it’s stronger. Again thought am only a diyer but built my extension last year and it’s still standing!