Sloping driveway - Sub base build up

[Marco66]

Hi, and thanks for letting me join.
I have a problem with a fairly steep driveway in Spain. It has heaved and destroyed itself and needs to be replaced. I only want to do this once!
MOT Type 1 is not available. I can get granite gravel 40mm to dust but it doesnt bind like type 1.
So my plan is to excavate about 400mm, compact the subsoil with a 10ton vibroller and lay 150mm or so of gravel. Compact that with the same roller and lay 150mm leanmix on top, compacted with a wacker plate.
Finish will probably be tarmac, but could be block paviors.
I will put land drains diagonally under the road into a land drain running down one side, to take any water away from the area. Road is about 100m long, so including a wider parking area it will be 500sq metres or so.
I would welcome any input, suggestions etc to help me make a success of this! Thanks.

[Tony McC]

Why has the existing driveway heaved? I'd want to resolve that before starting anything new.

Rollers on steep slopes - always great fun! :laugh:

That crushed granite they use in Spain and Portugal is usually not too bad once it's properly compacted. Try wetting it with a hose before compacting: that often helps.

If you opt for block pavers, I'd *strongly* recommend intermediate restraining courses along that long length. They will help minimise/precent the inevitable creep that occurs on steep slopes.

[Marco66]

Hi Tony,
Rainwater drainage, or lack if it, is the issue. They never consider this in our part of Spain. This access was used for years with occasional scraping/ levelling, adding concrete in places, hardcore in others.
So, drainage collection from the top and at intervals diagonally across the road into a main land drain running alongside and into a soak away. This will contain and direct underground water and also collect rain run off from the road itself.
Wetting the gravel will help with compaction, but I am nervous about using it alone as, when it dries again, it fragments. So will it be a good base for tarmac? Hence my idea of leanmix. What do you think?
My preferred finish is tarmac, partly because of the inevitable creep you have mentioned with pavers, and also for putting the road back into service quickly.
I suppose my question really is about the use if leanmix? Good idea?
I'm looking forward to the fun with the roller!
Cheers, Mark

[Tony McC]

Leanmix is fine in that sort of job, but you *will* need movement joints....and Spanish concrete.....mmmmm. Least said: soonest mended!