Rubble Mixed With Cement or Bottom

[Dave1UK]

I have quite a bit of rubble/chipped slab pieces and old concrete that are solid and want to incorporate into my subbase rather than disposing of.

For my subbase I'm basically laying concrete, but wonder whether I should mix this into the mix itself or should they be on the "bottom" whereby then I just sort of pour and compress dry mix on top if that makes sense?

Thanks.

 

[Wayners]

Crushed concrete you can buy and use as type 1.
You can smash up old concrete and bricks and use as hard core.

Not sure mixing up old smashed slabs to make concrete. Always good to use building rubble as hardcore or make up ground