Laying on top of tarmac - Can it be done?

[DaMann]

My house has a drive and turning apron of about 120M2. It has a tarmac surface which has been down ~20years and is in good condition. Its only problem is that it looks like, well, tarmac!

I was considering drilling it at 300mm centres, blinding with a 25mm sand layers, then a geotextile topped by 60mm concrete paviors.. The area has walls or curbing on all sides. Does this sound viable? It seems a great shame to have to pull up a good hard compacted surface and then run it to landfill.

PS admin, ignore my note about not having access to this forum, the mind in the machine has obviously let me in!

[Tony McC]

It can be done, but you have to consider the effect of building up the levels and how that will impact on the DPC of any buildings.

You can see a typical x-section here - note that the geo-textile goes underneath the laying course, not on top of it.

[GB_Groundworks]

its going to take a long time to drill through at 300 centres? hope you have good patience and a good drill.

watch out for your drains and any utilities depending on depth etc.

i'd always rip out and start again because i wouldn't know what sub base was under the bitmac but thats as a contractor.

[Tony McC]

300 c/c is not necessary. I think the usual for a commercial pavement is a 750mm grid with 50mm cores.

[GB_Groundworks]

could you theotretically pop the holes with a pecker on a machine?

[Tony McC]

Yes but.

The problem is that if the base macadam is tough/brittle, the force of the pecker can fracture the base, compromising its strength and the reason for it being there (in highway applications). However, this rarely stops contractors from doing it, especially if the RE is rarely onsite or knows sweet FA about the correct methodology.

[seanandruby]

make sure you use a core drill rather than an ordinary bit and be mindful of buried services