Page 1 of 2
Posted: Thu Jul 25, 2013 6:58 pm
by rimexboy
Well it's now been down only 4 years and I'm noticing a few problems,
Here is the Build thread when I done it.
I've noticed that a lot of the slabs seam to crackle when walking in them, the pointing round them seam fine but its like walking on a dusty slab,
The more I look the more I find, I do drive my car over it quite a lot only the circle side they seam no worse at all.
I do have a about 5 areas you can see pointing is missing.
Am dreading the worse here to be honest, this has a concrete sub base and then every slab laid onto a full bed with sbr I think it is called....
Yes it's had some extreme weather on it snow frost rain and very hot sun, but surely it should last longer than this..
Tips advice please
Posted: Sat Jul 27, 2013 3:39 pm
by r896neo
Crackiling when walking on them sounds more like delaminating rather than rocking. Don't panic though its probably not.
Where is it from.
As for the pointing what did you use.
Either the product was bad, the pointing was not well done or worst case the slabs are moving.
Posted: Sat Jul 27, 2013 8:23 pm
by rimexboy
Nustone, sand and cement,
Cheers
Posted: Sun Jul 28, 2013 9:39 am
by r896neo
Try tapping the slabs very lightly with the hard handle of a screw driver. The sound of a hollow flag is like a higher pitched knocking of a door whereas delamination is a very short cracking sound but this can vary depending on how deep it is.
As i said before, assuming your mix was ok the pointing failure is due to poor instalation i.e not enough compaction into the joints or because the flags are rocking.
try lifting one of the flags in an area where the pointing is bad. If you can remove all of the pointing around one flag you can then check if it is rocking on its bed and check its on a good full bed.
Posted: Sun Jul 28, 2013 9:44 am
by rimexboy
Ok thanks for that, it's a full bed under all of them for sure,
I drive my car over them they ain't rocking just crackling, I think it's got to be the pointing fecked..
So my next question is how do I get the old pointing out grinder?
Posted: Wed Jul 31, 2013 9:18 pm
by r896neo
Well as i mentioned the pointing will only have gone because the flags are moving or the pointing application was bad. Raking out and repointing will just fail again if there is any movement in the slabs.
Rake and chip it out with a combo of grinder and plugging chisel. I find a grout rake a useful tool too.
On a joint grind 2 lines each a few mm away from the sides of the flags then break out the middle channel. Then you can usually pry away the mortar in contact with the stone using a poiinting trowel. This saves having to go too near the stone with a grinder or chisel.
Posted: Wed Jul 31, 2013 9:23 pm
by rimexboy
thanks for the reply...
I did notice that walking on a couple during heavy rain it was blowing air bubbles out of the side...
Posted: Wed Jul 31, 2013 10:14 pm
by lutonlagerlout
read this thread with interest
IMHO you should not be running motor vehicles over patios at all
you made that bed now you get to lie in it 
something bad has happened
sorry simon
LLL
Posted: Thu Aug 01, 2013 7:26 am
by rimexboy
Tony thanks for that, I'm pretty sure that others have used Indian sandstone as driveways...
This has all been laid on a solid foundation of concrete and hardcore then on top of that then the slabs have been laid on a full bed as you go..
Posted: Thu Aug 01, 2013 9:09 am
by London Stone Paving
Simon
Is it just the areas where you drive the car that are failing, or is it other areas as well?
Posted: Thu Aug 01, 2013 11:23 am
by lutonlagerlout
not being arsey simon ,just something I have observed over the years
slabs aint suitable for driving on
cheers LLL
Posted: Thu Aug 01, 2013 11:34 am
by r896neo
Not sure on others opinions but i always thought laying any unbound material such as MOT over a solid concrete slab was a big no no.
It will hold water really badly and cause the type of pumping problems you describe.
Posted: Thu Aug 01, 2013 1:17 pm
by rimexboy
Steve I have this problem all over places I can't even drive on...
Tony I did not think for a second you was being arsey, I'm just trying to say I'm sure others have the slabs on drives tony, forgive me if it sounded wrong...
As for the car I keep to the circle side only, some slabs crackle when stepping on, and if we have had heavy rain some give bubbles when stepped on, this is happening all over near the step by the doors and also round by the side of the conservatory..
I've had a closer look and some of the pointing has come out in places as well
Also this is a solid concrete base with hardcore in it and even some steel bars... Then the slabs was laid on top using a full bed of mortar under every slab...
No loose type 1 or anything else is in it at all thanks
Posted: Thu Aug 01, 2013 2:17 pm
by TheRockConcreting
rimexboy wrote:Also this is a solid concrete base with hardcore in it and even some steel bars...
Been laying concrete all my life but have never seen this before!?
I think your referring to the aggregates in the concrete as hardcore if not i'm lost, this concrete under the slabs could be failing, do you know how thick the concrete is, what strength and was it air entrained.
Posted: Thu Aug 01, 2013 4:42 pm
by rimexboy
Sorry the broken hardcore is at the base with the concrete poured on top it was a 3 in 1 mix, and was not air entrained, it was laid over a few days and mixed by myself and tamped down, it's 6 inches thick...
That was left for a few weeks then the slabs laid on top with a full bed under every slab...