Tarmac base layers - Tarmac overlay on concrete slab

[liam john Price]

Please can someone offer me advice on tarmac drive/road overlay.
I have a small development which involves a tarmac parking area. The site is predominately covered in 200mm thick concrete slab. I want to use this as a sub-base, instead of breaking it all out. However, the concrete doesn't cover the whole area which is to receive tarmac.
Is it possible to have areas which are concrete sub-base and then areas which are hardcore sub-base?

[Stuarty]

Im not certain, as i dont do much tarring at all, but i would think its possible to do so. Dave_L will be able to tell you

[lutonlagerlout]

dave l where art thou??
according to rogue traders tonight as long as you smear a load of watered down black stuff on it your ok
alternatively look
here about a third of the way down
cheers LLL

[Dave_L]

Where it is possible to lay tarmac over an existing conrete surface, it is not ideal and is obviously not reccomended.

We've done it a couple times (where the job/customer has dictated it) with no ill-effects in the short term.

This parking area - what is expected to be parking there - anything heavy?

Obviously a good clean surface with a liberal application of Leotack (Tack Coat) beforehand (in dry weather!!) is the way to ensure a good key is obtained.

[liam john Price]

Thanks everyone for your advice, it has been really useful. This site has been an immense help since l discovered it.

Dave L, the site is quite large, at least 20m x 25m, mostly covered in concrete with the odd made up ground in place, mostly round the edges of the proposed tarmac area.
The tarmac area will be used for domestic traffic, cars for 12no. flats. No heavy plant or machinery. The bins will be collected from outside the development.

Any advice would be most welcome and greatly appreciated.

Cheers.

Liam.