Paving Onto Crusherdust

[Smiley Guy]

Just caught onto this thread - I'm still not sure if people are saying it's OK to lay straight onto crusherdust. Providing the layer of crusherdust is thick enough, and ignoring the issue of diffuculty of screeding; will crusherdust (crushed blue metal) be OK to lay straight on top of. My paver is doing a job for me outside right now - paving straight onto 100mm of crushed blue metal/crusherdust. Is this just as stable as using sand? It's for foot traffic only.

[Bleedin Thumb]

Hi SG,
There seems to be a couple of opinions here. I've done a bit of paving in my 24 years - one job alone was 4500 sq.m. so IMHO
You can use crusherdust instead of paving sand, ideally no thicker than 50mm this is called your bedding layer.
Under your bedding layer is your subbase layer. This should be be a compacted thickness of 75mm min for pedestrian or 150mm vehicular made from DGB 20 roadbase (or recycled). Compaction for pedestrian by flatplate or vehicular by vibrating roller to 98%.
Under that layer is your subgrade layer. Most of the time in a domestic sence this gets ignored but on a commercial vehicular paving job this may need modifying to acheive longevity and strength.

The other opinions expressed on this thread dont seem to differenciate between bedding and subbase. Whilst for most domestic, pedestrian jobs this may be OK, if your subgrade has a poor load bearing capacity,ie sandy or plastic clay soils then I would feel better if the subbase was roadbase at the very least.

Crusherdust does compact better than pavingsand but the point I'm trying to make is it doesnt compact anywhere near as good as roadbase and that is what you should use as a subbase.
SG What your pavior is doing is probably fine for domestic paths. My signiture used to read "If its worth doing, its worth overdoing" which is my philosophy on commercial projects.
Sorry for the long winded answer.