Mixing ballast for concrete

[Scoby_Beasley]

Building a base for aviary and have been told to use 3.5/1 ballast/cement as the base is only 1"min tapering to 2.5"max on old slabs (already there).
Weight not an issue as I've made frames from ally.
Question is how much sand should I add to pea shingle I already have and want to use up.

In other words can anyone suggest a ballast/sand/cement mix for me ?

TIA

 

[masona]

See this or this !

 

[Scoby_Beasley]

Cheers masona, got that down to 1:2:4, cement,sand,ballast for foundation work (need to build a wall one side to extend) and 2:3:6 for concreting.

Thanks a lot