Posted: 18/10/2013 at 21:23
If you can, then get rid. We have taken over 30 tons of rubbish like this from the garden (and yes I do mean 30).
However, many of our grass paths still have a thick layer of broken brick etc. underneath them. You cannot put a fork in , in a lot of places without hearing the dread, 'Clunk' as you hit something solid.
Also there is a largish area, covered now in Bamboo, where there is a layer of about 18 inches of top soil over a solidish concrete surface. The Bamboo may now have put its roots through cracks and in to the whatever is underneath.