Can I use light weight internal blocks as hardcore

[Jeffb]

Hi all , I have an area that will be a patio that requires the levels raising , my question is, is it ok to use the waste off cuts from the light weight internal wall locks like a thermalite block ? Will these off cuts degrade in time and crumble to nothing ? I have approx 8m x 3 m to built up by 300mm . I will also use my old roof tiles and any of the concrete block off cuts etc then crushed concrete over the top. I will probably only be able to use a walker plate to compact the area. Any ideas any one? Thanks Jeff 

[Dave Jones]

a few mixed in wont hurt but you dont want all of it. They hold onto water which come winter time the frost turns them to dust over time.

[Jeffb]

Ok that makes sense 

thanks Jeff