The Brew Cabin

Posted: **Thu Jun 18, 2009 3:31 pm**

Hi,

My existing driveway is in bad condition with severe deep tracks from years of wear and tear. However the surrounding area is pretty sound. I'm casting my own 45mm slabs and ideally would like to finish the driveway with them. Please can you advise me on the best way to proceed...my thoughts are as follows :

The driveway is away from the house so i have no problem re: dpm level.

Need i remove the entire drive, lay a sub-base, add bedding layer and slab. Or can i simply remove the damaged areas, infill and continue as above.

I've read that 40-45mm slabs are risky for driveways - will these be better if I bed them on c20 mix(as opposed to semi dry), and how deep/wet should this layer be?

I could deepen my slab molds by making timber frames and clamp them to the mold...thus outputting 65mm slabs. I use a vibrating table, so they're quite well made, but obviously no match for pressed slabs...would this be worthwhile rather than casting 45mm?

Where the tyres run, could i lay gravel tracks and slab the rest? I know this is a pain in the ass to maintain, but is it worthwhile given my situation?

Very much appreciate any advice,

Cheers,

Posted: **Thu Jun 25, 2009 7:28 am**

Nobody else seems to want to have a go at this one so here's what I'd do, based on some advice that Tony gave me some time ago, then mixed with some of my own thoughts. Let me preface this by saying I'm a general builder and not a driveways expert but here's what I'd do if it was mine.

I asked Tony about using Indian paving (560mm x 845mm and 560mm x 1120mm, usually 20-40mm thick) or PCC slabs (600mm x 900mm (50mm thick?) for a driveway. He recommended that whichever was used they'd need to be laid on at least 100mm mass concrete and to use 150mm if the ground is suspect in any way. The flags could can be laid directly onto the concrete if you can work fast enough. Use either 20 Newton concrete, which is also known as ST4 or 1:2:4 mix.

I wouldn't be able to work fast enough so I'd lay them on a bed of 10:1 sharp sand/cement mix, 50-75mm thick, as recommended elsewhere on the site (although in practice my mix is always stronger at about 7-8:1 because I always err on the side of caution).

If you're pointing them as opposed to butt-jointing, I'd recommmend from personal experience (following Tony's advice) Gftk VDW840. I guess Romex do a traffic-duty equivalent.

As for preparation, if it was mine I would dig the lot out and have done and probably even, for the price of it versus the peace-of-mind, wacker 100mm MOT1 on the ground before concreting.

They key thing, to my mind, is that the flags be fully supported so they can't go anywhere, sideways or downwards. To that end, you either have to haunch the sides of the driveway with concrete or make the drieway considerably wider (i.e. at least a full slab) than the vehicles using it.

Personally I wouldn't go for gravel tracks because the gravel would go everywhere but, from a construction point of view, it would be easier and on the face of it less expensive. Again, I'd dig the lot out and start from fresh. If the gravel tracks are the outermost areas then you'll need some sort of edging to stop the gravel spreading sideways. Then wacker 100mm MOT1 between the edgings. If you're sure that nothing's ever going to drive outside the gravel tracks, lay your flags down the centre on a sharp sand/cement bed, then fill tracks with gravel, 100mm deep. I might even put a Terram-type layer between the MOT1 and the gravel to prevent the two getting mixed over time - maybe others have thoughs on that (or indeed on all my suggestions!)? If there's any risk of vehicles driving on the flags then I'd say you're back to mass concrete for the whole job.

Does that help or should I stick to general building (or not even that)?

Posted: **Thu Jun 25, 2009 1:10 pm**

urgh, ummm ???

Posted: **Thu Jun 25, 2009 2:19 pm**

Very helpfull bodge

Cant add much to paul's post apart from i wouldnt be laying 40mm flags on a driveway and definatley not if theyve not been proffesionally manufactured.

I wouldnt bother with the gravel tracks id slab the lot also dont see much point of flags down the middle?, but thats down to personal preference i think it looks crap,

Ive just done a driveway and laid "council greys" 50mm thick flags on a full bed of 100mm concrete.

Posted: **Thu Jun 25, 2009 2:24 pm**

Also dont lay terram between the layers of stone, and dont lay the deco gravel 100mm thick - if you do go for gravel tracks that is.

The Brew Cabin

Paving over old concrete driveway