Restoring Tarmac Permeability

[Dan F]

 

We had 70mm open-graded tarmac laid on our drive just before we moved in 3 year ago.   Since then, we've completed landscaping works and one of the few remaining things to complete things is to lay some resin.  The result needs to be permeable and shouldn't pool.

 

Permability after it was installed was great, with only a very small amount of surface water for a short period of time if there was heavy rain non-stop for a week.  However,  duing landscaping work, getting MOT and topsoil on the drive was pretty much unavoidable, and while it is still somewhat permeable we do have significant pooling in a number of areas.

 

I haven't wanted to rush into getting resin put down as we don't want to proceed with resin only to find that the resin doesn't drain.  The resin supplier has suggested a few things to mitigate this:
- Drill holes in the tarmac, especially in areas we see pooling currently.
- Use 10mm vs 6mm aggregate to increase permeability of resin.

- Use 35mm resin on a grid, rather han 18mm directly on the tarmac as orginally planned (so resin layer can hold more water and water can distribute within resin layer).

 

There are all great suggestions, and probably ones that we should follow, however I'd feel more confident if we could restore the permeability of the tarmac first.  Pressure washing just move the fines around and doesn't improve things, so we need a different approach.

 

 

According to Tarmac:

  Quote

 

RESTORING PERMEABILITY THROUGH ‘HYDRO’ CLEANING

Under controlled pressure these machines jet water into the surface to agitate the solids back in to suspension and then under intense vacuum draws them out of the surface, restoring hydraulic conductivity levels some thirty times more than that required for a very heavy UK storm event. Although more specialist than a traditional road sweeper, this jetting plant is readily available for hire across the UK.

 

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However, the only versions of this  that I have found online as large road-sweeper machine and charge £1000's day rate.  Given drive is only 120m2 or so this does't make sense, yet I can't find anything smaller/cheaper or any self-hire options.  I may well be looking in the wrong places though.

 

I've wondered about hiring a higher power/capacity wet vaccum and then trying to do this myself and have also seen a product call "rotaryvac" [1] which I thought about trying to hire somewhere, but thought I'd see if anyone here has any experience of advice before I start experimenting..?

 

 

[1] https://equip2clean.co.uk/products/kiam-rotaryvac-21-rotary-floor-cleaning-tool-with-fluid-recovery-vacuum-system