Natural stone slabs on driveway issue

[shd1970]

So a builder i engaged has laid some natural stone slabs on my drive as per my request for some stepping stones
Drive has a good solid 4" of hardcore

Now a breakdown of communications (well i say that...he didn't ask me but i most definitely didn't ask for this and didn’t expect to have to watch over him !) has meant for some reason, he has laid them on a bed of lets say, the best part of 2-3 inches of mortar mix meaning that they are ridiculously high as the plan was just to then gravel/chippings the non-slabbed area around them and use to park our cars

Not sure of the mortar mix he used but we had equal amounts of both building sand (slightly more building sand actually !) and sharp sand and there is less building sand left so assume that its a softer mix.
I had provided him with "easy prime" slurry which he has used also

So options as I see it are take all up (17 x 600mm x 600mm) and re-lay using a far thinner mortar bed on the hardcore base as I can't make the driveway up with more hardcore due to a manhole that is level with the top of the hardcore

1. Does anyone have any other option they can think of to make this good rather than taking up and re-lay (they have been down for 3-4 weeks now) ?
2. what's the though on by drilling out the mortar to weaken, whether the slabs will come up without breaking ?
3. if i re-lay them on a low 1" mortar bed, can anyone confirm what sort of ratio mix i should be looking to use please (building/sharp/cement) as i know this is highly debated ?

Thanks in advanced

Yours....gutted !!!!

 

[mikeey84]

Are the slabs going to be driven over?

If so, your builder has probably done it correctly, as natural stone is pretty soft so needs a good thick bed of mortar so they don't break.

If they are not going to be driven over, then they can obviously be bedded on less, but still needs to be 40mm ish.

Could you not raise the manhole? Having it level with the hardcore is an error, as anything on top of the hardcore is going to be higher than it.

 

[shd1970]

thanks for the reply mikey

So :

Are the slabs going to be driven over?
If so, your builder has probably done it correctly, as natural stone is pretty soft so needs a good thick bed of mortar so they don't break.

nope, not to be driven on....purely stepping stones to walk on

If they are not going to be driven over, then they can obviously be bedded on less, but still needs to be 40mm ish.
Could you not raise the manhole? Having it level with the hardcore is an error, as anything on top of the hardcore is going to be higher than it.

The only think going on top of the hardcore will be the gravel/chippings
I know its likely not how a company would deploy a proper gravel drive (dig out, hardcore, blinding sand, membranes etc etc) but that would likely come in at a cost of thousands, but this is sufficient for what we need and the hardcore has been down for 15 years (i did it and its solid still now

So effectively, all we were looking for was for the slabs to be stuck down at the lowest height/straight onto the hardcore

 

[mikeey84]

OK, thats clearer.

Still think it would be easier and quicker to raise the manhole and leave the slabs, then match slabheight with gravel (you need a good 40-50mm of gravel if going for 20mm gravel size)

Might cost you a bit more in gravel, but will save you the effort.

Also, hardcore then gravel on top is a perfectly fine method for a gravel driveway, no need for membranes or sand unless on very soft ground (membrane goes between ground and hardcore, not hardcore and gravel)

 

[shd1970]

Here you go Mikey......he used more like 120mm instead of 40mm !

 

[mikeey84]

Here you go Mikey......he used more like 120mm instead of 40mm ]

Ok, that's a bit more than you said initially!

If the height is OK in other respects, and they work for your purpose, then I still stand by my suggestions, even if they look like that now. Once gravelled, they will look fine.

If they are too high for use (ignoring what they look like) then id remove, but you may struggle to not break them, especially if they have been bonded.

 

[shd1970]

apologies Mikey, just went out and measured for the photos !

there is a slight bump on the drive (its not a nice graduated slope) hence i would rather not add more hardcore and whacker down as it will take the overall drive level up further but i will reconsider it
regarding the manhole, do you have any ideas of something that i can just drop on top of the manhole, allowing it to be easily removed should it need to be accessed perhaps ?
Where the manhole cover is is exactly where the front drivers side wheel is positioned when that car is on the drive, so one of my early thoughts was to drop an old-skule type 3x2 slab there, nice and heavy and strong and wont break but can be removed if needed, and then hardcore up the rest of the drive to that thickness ?

A bit "heath robinson" i know but just a thought as i an conscious of the effort involved in taking all 17 slabs up and rebedding, and breakages