What to do with rubble
I've started to remove a patio area and the builders used about 6 inches of sand-cement mix to create the base, plus the odd left over brick etc. While I have complacted clay I thought I could dig some of it into the clay for drainage (preferably the smaller bits not the big chunks) but what can I do with the rest? I want to also build raised beds but they are only going to be 20cm raised, should I dig some of the rubble into the bottom layer of the raised beds? How many cms of good topsoil/compost will I need for the plants to be happy?