New patio - concrete between slabs breaking up

Pythagorous

We recently had a new patio area put down which involved raising the ground level. The slabs were laid on compacted gravel. They have only been on a couple of days, but already some of the concrete between the slabs seems to be breaking up as you can see here http://img.skitch.com/20100707-cpttkyh52w3cm6q22bkkkphbsm.jpg. There appears to be a very slight movement in the paving slabs which has me wondering if the builder should have laid some better solid ground below the slabs.

What do you guys think? Would you be peeved? Is there any way to prevent this? I'm hoping the only option is to take the slabs up!

macman

It's not concrete, it's mortar. Looks like it has been allowed to dry out too quickly-hot sun on it in the last few days maybe-should have been covered up.
However if the slabs are moving then the mortar joints will just break up again if redone.
Was there nothing else put down as a sub-base? Gravel alone is not sufficient even on lightly trafficked areas. No sand or hardcore?
Personanly I would always use compacted hardcore and ballast, concrete and then lay the slabs on that.

Pythagorous

Thanks macman. I think it was just gravel, was never actually discussed by the builder and I never even thought anything about it. I haven't paid him yet, just trying to gauge if I'm being pinickity saying it needs sorted! Sounds like its going to be quite a job to sort it out :-(

Do you thunk I'm being unreasonable to suggest a proper hardcore base is required and that he needs to dig up and redo!?

macman

If he had to build it up anyway, then he should have built it up with something stable. I can (almost) understand someone bodging it when it has to be dug out, but not when building it up.
Didn't your quote specify what the foundations would be-not just 'chuck some gravel down and lay the slabs on top'? The whole lot will have to come up and be redone if that is the cause.

Pythagorous

macman wrote: »

If he had to build it up anyway, then he should have built it up with something stable. I can (almost) understand someone bodging it when it has to be dug out, but not when building it up.
Didn't your quote specify what the foundations would be-not just 'chuck some gravel down and lay the slabs on top'?

The original work was for a conservatory and when the builders started they suggested building up the patio area to the side (largely as it meant they could dump some of the digging work in the area and also meant new steps didn't have to be dug out). We agreed that was fine and that we would just pay an extra £150 for the extra labour. So unfortunately no written quote was provided for the patio area :-(

savemoney

Yes its mortar

I thought you laid slabs on sand not gravel


http://www.pavingexpert.com/screeding.htm

Pythagorous

savemoney wrote: »

Yes its mortar

I thought you laid slabs on sand not gravel

mmm maybe this builder just hasn't a clue!

savemoney

spam merchant reported markholsomback

wallbash

Did you see the 'builder' point the slabs ??
Or did he just brush a dust/sand mix.

Pythagorous

wallbash wrote: »

Did you see the 'builder' point the slabs ??
Or did he just brush a dust/sand mix.

Didn't actually see him do the mortar filling bit.

He still has to finish a couple more of the slabs, so this photo shows the base

http://img.skitch.com/20100707-ecq7y6jcxc4jj8i5569jcjkpcp.jpg

We nearly had a full blown argument when I mentioned something minor yesterday so I just want to make sure I'm not being unreasonable before bringing it up. A friend was of the opinion that compact gravel was the norm and unfortunately some loose mortar was quite a common inevitable issue.

suisidevw

I'm no pro at this but should it all be sanded and 'whacked'?!