Indian sandstone drive?

[Aidan]

No, but I know a man who has.

[Joe]

I'm looking to replace the broken slate of an old driveway with some kind of reasonably decorative paving slabs. I'm warned that a minimum thickness of about 45mm in cast concrete slabs is needed for parking a car on, which seriously limits the possibilities. Basically, only fairly boring slabs in one or two sizes come that thick.

I see a lot of Indian sandstone advertised, at about the same price as decent concrete. Thickness is 25-35mm, but in sandstone this is said to be OK for the load. Can anyone confirm that? Has anyone actually used this for a drive?

[Aidan]

May be there's a good reason for it.

Pavingexpert has got a discussion forum, the Brew Cabin (I think, never used it). Ask on there.

[Joe]

Yes, an excellent site, but fairly noncommital on this subject. Only seems to endorse 100-150mm stone for vehicular use. This seems excessive to me.

[Ian Stirling]

Sandstone is quite weak, compared to concrete (well, some of it.)

I'd only use 20-25mm, if it was bedded in ~100mm of concrete.

[The Natural Philosopher]

Ive used it for a patio, and believe me it is not strong. You would need to essentuially use it to surface a full blown concrete drive - i.e. make a load bearing concrete slab, and then set the stones into the top of it.

Even then don't let the 30 tonners reverse onto it.

[The Natural Philosopher]

The key is to support it fully on a wet mortar base over a rigid sub-layer.

[AlexW]

I have used this on my patio and in my house and I reckon its stronger than equivalent thickness pre-cast concrete flags. However as others have alluded its how they are supported which will be the key. I imagine a full mortar bed on something quite solid would be a must.

I have also seen this stuff used on a farmhouse driveway up the road and this looks pretty good 2 years after I started walking past that drive. Not sure what kind of traffic it gets though (probably nothing more than the odd range-rover & horse box). No idea what the flags are laid on to either.

Also, IIRC in my case the flag thickness varied from 15mm to 50mm thick at the extremes. If you get the opportunity to hand pick thick ones from a crate it might help a little.

HTH,

Alex.