10mm or 20mm gravel.....and what type?

[Thorfun]

I've been researching gravel types for our driveway. reading https://www.pavingexpert.com/gravel01 it states:

 

Quote

Any size gravel or other surface dressing can be used for a driveway, although 10mm is the most popular choice. Any aggregate larger than 20mm poses a hazard if flicked up by the tyres of traffic using the driveway.

 

I kind of agreed on 20mm with the ground worker but now I'm wondering why 10mm is the most popular? 

 

Paving expert then goes on to say 

 

Quote

A harder gravel, such as granite, flint or magnesian limestone is a good choice for driveways. Some of the softer local gravels, such as Cotswold buff limestone or Keuper sandstone, are relatively soft and can be rapidly crushed to dust by repeated trafficking.

 

I heard that granite gravel is a great solution but on a normal household driveway is there really a risk of crushing software gravels? it's not like 100s of cars go on it every day.

 

so, I'm interested in opinions on gravel size and type for a driveway. it's pretty large (don't have an exact size but probably around 150m2) and will most likely be edged with steel. 

 

cost is definitely a factor as all we have left is a smallish portion of our VAT reclaim to finish off the landscaping

[Mr Punter]

Smaller stuff can get stuck in shoes.  Don't lay it too thick!

[Thorfun]

5 minutes ago, Mr Punter said:

Smaller stuff can get stuck in shoes.  Don't lay it too thick!

10mm though? I guess so.

 

paving expert says 40mm deep at most

[Onoff]

Flint gravel surely would be hard on tyres and any sharp one would puncture them? 

[ProDave]

It is the shape of the gravel that is important.

 

You will regret getting round pebbles, whatever size, they don't interlock and will constantly move around when driving on them.  Instead you want crushed or otherwise irregular shaped gravel that interlocks together better and so does not move around much as you drive over it.

[Redoctober]

We have quite an area of "driveway" and opted for 20mm granite chips. In my view they work much better than any smaller stone, as they do stay in place better. Anything smaller would be too easily distributed I feel - see photo for our set up - Occasionally, / rarely, I will rake them over but other than that, job done. 

[BadgerBodger]

Angular gravel is the way. Essentially quarried only. As everyone else says river bed gravel, shingle, pea gravel or otherwise, spills, ruts etc. 

 

Up to 50mm of angular gravel on a good sub base (minimum 150mm MOT) with woven geotextile below is reasonable (substrate dependent) for passenger vehicle. The MOT wants compacting well (twin drum roller ideally) and the gravel should knit well. 
 

I recently did a temp car park on bad ground and we swapped out the gravel for 150mm of 40mm clean compacted and it’s held out for 3 years of heavy use. 

[Redoctober]

38 minutes ago, BadgerBodger said:

 The MOT wants compacting well (twin drum roller ideally) and the gravel should knit well. 

 

This is a key element too - all in the preparation. As for a woven geotextile membrane, we were advised against having it by the landscaper. His thoughts were it would only get torn over time - the sub base we had down with the 20mm on top would be good enough and I have to say he was right. No weed growth as such, just what gets blown in. Easy maintance all round. 

[Gone West]

We've got 14mm granite chips gravel. I think small stuff would get stuck in the tyres.

[BadgerBodger]

@Redoctober I use the membrane below the type 1. It’s mainly out of habit now as every road, car park, plaza I do seems to have it so when I’m doing myself I figure I never have to go back to that spec so if it’s good for them, it’s good for me. Anecdotally, in my experience it helps with ensuring you don’t get such a migration on fines (upward) from formation level. Over simplifying it, geogrid type product greater resist punching down. 
 

I’ve had some pretty bad ground in my time and pretty much every time a combination of geogrid, membrane and stone in varying thicknesses generally gets the result we need. In some cases for pile mats I’ve put in 1400mm stone!! The rest of the site received cement stabilisation. 
 

 

[crispy_wafer]

3 hours ago, Redoctober said:

We have quite an area of "driveway" and opted for 20mm granite chips. In my view they work much better than any smaller stone, as they do stay in place better. Anything smaller would be too easily distributed I feel - see photo for our set up - Occasionally, / rarely, I will rake them over but other than that, job done. 

Lovely job, I like!  Suits your place nicely.

[Alan Ambrose]

1400mm stone? That is, 1.4m diameter boulders  This is under suspension bridge piers?

[Conor]

We've 10mm mixed stone on gravel grids. You really, really need grids for small stones.

 

[Thorfun]

1 hour ago, Conor said:

We've 10mm mixed stone on gravel grids. You really, really need grids for small stones.

We don’t want/can’t afford the extra expense of grids. 

[BadgerBodger]

1 hour ago, Alan Ambrose said:

1400mm stone? That is, 1.4m diameter boulders  This is under suspension bridge piers?

No!!! The total build-up was 1.4m. If I recall it was geotextile, geogrid (Tri-axial) 300mm 75-125 stone, three times, with 300mm 6f2 and an MOT capping to make-up. 
 

It was a for a pile mat. The permanent structure was built on driven piles. 
 

33 minutes ago, Thorfun said:

We don’t want/can’t afford the extra expense of grids. 

 

I don’t think It’s absolutely necessary. I was looking to use grid at my place but given that the drive is caked in mud at potato harvest I figured grid wasn’t any use as it would be gunked up with much after the first winter. 
 

 

[Conor]

53 minutes ago, Thorfun said:

We don’t want/can’t afford the extra expense of grids. 

Go for 20-30mm stone then.