Discoloration of old riven - Paving going black in 12 months

[Bob R]

Some slabs (maybe 5%) within a patio laid 12 months ago with Autumn Cotswold Old Riven have very bad surface discoloration and are almost black.
Is there any experience of this problem and any explanation for this undesirable and unexpected feature?

[Tony McC]

Impossible to comment without seeing the affected flags

[SFLandscape]

Pictures of Rob R's problem, does any one what has caused this?

[Pablo]

It may be that there is a cavity in the mortar bed. If you're game then lift an affected slab in an out of the way spot and see if this is the case. If it is then get the contractor back and get him to sort them out. Other than that I don't have a clue.



Edited By Pablo on 1248123385

[SFLandscape]

I am the contractor who put them down, i have been and had a look.
When you look at them closer there is some colour changing on the edge of the paving as well as what you can see, they have been laid on a full bed, i've doing this work for 19 years and have never come across this before.
We have been in touch with Bradstone and they say this can happen but will disappear, however they then offered to refund the money for 60 slabs, but this doesn't allow for the cost of replacing them.
As the contractor i am working with the customer to sort this out and it was me who surgested putting it on the Paving-expert, after all we all come across things we have never seen before.
Just dont want to except what Bradstone is saying to find out they shafted us.

[lutonlagerlout]

it looks like a manufacturer's fault to me,maybe they use recycled aggregates in their mix
i have seen the void marks pablo is on about and this doesn't look like it
summat has reacted with summat,for sure
LLL

[henpecked]

Is it iron oxidisation?
Looks random enough for it and the right colour.

Hp

[dig dug dan]

faulty slabs imo.

they shoudl re-imburse you the cost of installation. I know of one poster on this forum who has done just that recently with some slabs from stonemarket

nice looking job by the way

[Tony McC]

That looks very much like the problem experienced by another manufacturer about 18 months ago.

After much discussion, which went on for several months after posting that article, the consensus was that it's an alkali-silica reaction in the cement used to manufacture the paving. This is a troubled area of concrete chemistry and although it's been explained to me dozens of times, there is no universally accepted reason for it's appearance.

Put aside the why: I'm with Dan, Bradstone should be replacing the affected flags, paying for the labour cost of replacement, and bunging a few quid to the contractor for his inconvenience.

[SFLandscape]

Good News

Bradstone have agreed to replace the whole patio, paying for everything.
Problem was something to do with adverse weathering, not sure i understand but I think Bradstone need a pat on the back for excepting its a problem and paying for it , so good for them

[mickg]

thats good news and an excellent result

[lutonlagerlout]

Problem was something to do with adverse weathering

sounds like bollocks to me
adverse weathering?? the slabs were made for the uk market
but fair dos to them,they have swallowed it and will cough up
are they paying you to do it SF?
LLL

[Injured]

Good news and like you say pat on the back for the manufacturer for sorting it out.

[SFLandscape]

Yeah there paying for the lot , labour , materials & waste away.
However i think my customer will be looking at some different slabs.

Silver lining , i get to be paid twice for the same job and the customer is over the moon