Replies

1. 
   xMikeSmith | Mar 21, 2004 10:19pm | #1

   dudley.. i wouldn't use any cement or mortar to set your cobblestones.. i wouldn't have even put the 4" pad down.. but since it's there.. so be it..

   compact your 1" leveling bed and lay your cobbles tight.. then sweep sand or stone dust in to lock them.. it'll go faster, you'll get a neater job,  and you can repair it if you have any problems... also.. if you look at typical cobblestones... you'll see that this is how they  are laid.. no mortar

   Mike Smith   Rhode Island : Design / Build / Repair / Restore

1. 
   jarcolio | Mar 21, 2004 11:39pm | #2

   Mike -- tks -- I wanted the sealed look so thought a 1/2 inch all aorund would be fine -- I know its a lot of work -- 7 tons of granite cobble stones and am not looking for short cuts -- just wanted the best looking job and one that will really hold up

1. 
   xMikeSmith | Mar 21, 2004 11:52pm | #3

   i'm not sure what the "sealed look " would be.. but i've seen a lot of cobblestone.. some hundreds of years in place.. some laid two years ago..

   some here... some in Europe....... it's all laid tight with no mortar, then they sweep sand or stone dust into the  voids..

   i would guess that cobbles HAVE been laid in a concrete or mortar bed... i've just never seen it...

   i'm thinking of doing a concrete cobble at our gravel driveway entrance.. we get a little wash out there on an ongoing basis...

   here's some of the concrete cobble we laid at an entrance two years agoMike Smith   Rhode Island : Design / Build / Repair / Restore

1. 
   jarcolio | Mar 22, 2004 03:24pm | #12

   Beautiful work Mike -- I always open your pictures and am never disappointed -- fantstic look, scale and quality - tks, Dudley

2. 
   UncleDunc | Mar 22, 2004 12:16am | #4

   Like Mike, I've never seen anybody recommend laying cobbles on concrete. I've seen a couple of large scale paving jobs in DC that had concrete under them, but between the concrete and the paving was several inches of some kind of sand or stone dust mix.

   Here's a fairly authoritative UK site on stone paving. They have recommendations on substrates and there's even a page or two somewhere in there on sealing the joints with asphalt.

   http://www.pavingexpert.com/

1. 
   xMikeSmith | Mar 22, 2004 12:25am | #5

   unc.... that's  a great site... i bookmarked  that one..

   they say that rigid base is normally only used in special applications .. like heavy commercial traffic..

    the more common is the one i referred to... the flexible baseMike Smith   Rhode Island : Design / Build / Repair / Restore

1. 
   Piffin | Mar 22, 2004 12:54am | #6

   In an area like ours, with lots of water and freezing, I think the olde way of good draining aggregate base is right. I can imagine that in Georgia, for instance, where they have unstable clay soils and no frost, that the concrete substrate could serve a function though.

   Since he already haas a concrete slab base, it seems to me that he would need to use an infill of mortar between stones and then use a sealer to keep water out of the whole thing because if water gets in and freezes, it has no place to go now and it would lift stones out.

   But that's just my speculatijg. No direct experience.

   Wait a minute! Yes I do. we did one with brick pavers over concreete slab and footer down four feet and drainage under it all with compacted gravel. The brick were mortar set and then sealed. This is maybe 6-7 years ago and still in good shape. It's the one I've shown in pergola pictures. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   davidmeiland | Mar 22, 2004 07:24am | #10

   Mike! Take the rubbermaid bucket outta the picture next time you're shooting something that nice. Dang!

2. 
   BillMcG | Mar 22, 2004 06:24am | #7

   Just my two cents - we've seen cobblestones last a few centuries, but horizontal concrete doesn't fair as well. One more thing to consider when listening to the pro stone-dust camp.

   Doesn't granite dust harden over time anyhow?

1. 
   Piffin | Mar 22, 2004 07:08am | #9

   It'll firm up and get tight, but not hard. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

3. 
   Mongo | Mar 22, 2004 06:50am | #8

   If you're set on using portland, I wouldn't use anything with lime in it, a pre-bagged mortar mix, for example.

   If I had to complete your job, I'd consider troweling a bed of mix on the slab, then setting the cobbles in that bed, properly leveled and spaced. Then I'd follow with a sand/portland mix and broom it in to fill the joints. Tamp the joints to compact, then mist to cure.

4. 
   PhillGiles | Mar 22, 2004 09:31am | #11

   I have a cobble-stone driveway, and, just the cobble-stone or concrete paver driveways that all my neighbours have, there's no concrete or mortar, just fine sand that needs to be brushed in every spring. You want concrete, go for pattern concrete; but don't mix the two.

   .

   Phill Giles

   The Unionville Woodwright

   Unionville, Ontario

5. 
   specs | Mar 22, 2004 08:01pm | #13

   Follow-up:

   Are these true cobbles? Setts?

   A rigid/mortared system can work, and it is used in high traffic areas. I't just not common for residential.

   May want to add a bit of carbon black to the mortar to set off the grout lines between the stones.

   Slope for drainage.

1. 
   jarcolio | Mar 22, 2004 10:29pm | #14

   They are true cobbles -- I had not thought of the possibility of coloring the mortar -- I am going to go Mike Smith's route and just lay them in tight and brush the stone dust in -- it is a parking place that we will use for overflow so it will not get the "high' traffic

1. 
   jarcolio | Jul 29, 2004 11:31pm | #15

   Wanted to provide update and thank all for the advice

   Put down n 10 tons of cobble stones over 26 tongs of gravel -- worked perfectly -- have a good base of crushed stone that was packed down between 4" layers and then about 1 1/2" of stone dust; have a mortared in premiter of the Belgian Blocks 4 thick 8 wide and 10 long and then filled in with the 4x4x4 cobbles stone-- have them in a fan pattern and it all worked out well -- filled the spaces with more of the stone dust.

   I believe the secret to getting this really tight and pretty level was going back and getting pan vibrator and going over the whole thing (the lose cobbles) with a pan vibrator/compactor -- really smoothed things out and worked the stone dust in and around the lose cobbles ---- Dudley

1. 
   stonefever | Jul 30, 2004 02:19am | #16

   We won't believe you until you post pictures!