6mm to dust car park - Any advice on problems i may face

[caretaker]

Hi Folks

I'm looking to redo an existing overspill parking area with 6mm to dust. Area to cover is approx 550 square meters

It's probably over 10 years old and looks like it was originally just compact gravel approx 50mm in size.

I plan on using edgings all around & filling at a depth of 50mm with the 6mm to dust (obtain from a local quarry) over existing gravel surface then compacting with Dynapac CC122 Tandem Roller. Will probably need some water to help with compaction.

There is an area of tarmac approx 24 mtr square that is sitting a little low & will need covering/raising 50 mm. I could use some of the existing gravel scraped from the high points then compact and finish off with the 6mm or is it best to remove the tarmac and level with a larger grade gravel before using the 6mm to dust? (couldn't find a definite answer on this one)

We need to use small gravel, as this is in a school & the little ones use the current stuff as ammunition!

Not much money in the pot and with a ton of 6mm to dust for under £15 the head teacher is considering going ahead.

I've spent hours reading the site & found the advice invaluable. There will be more questions along the way no doubt, but your advice on the do's and don'ts would be much appreciated.

Thanks in advance

[Tony McC]

Don't put the dust over the blacktop - it won;t bind. Breakout the blacktop and either bury it elsewhere or cart it offsite.

6mm to dust is sometimes known as Self Binding Gravel (when it's a limestone, usually) and it needs a similar clean (ie: no dirt, mud, silt, etc) sub-base to bind to. It doesn't bind well to bound surfaces such as blacktop or concrete, and tends to scuff off rather quickly, so best to return to a granular sub-base.