Ideas on paving - Damp staining on granite paving

[Pissednbroke]

Hi

Novice paver here, I recently laid a 25mm granite patio over a compacted gravel and sand bed. What I have noticed recently is that the paving has a lot of damp patches appearing on it. See image attached.

Any ideas what this is and if it will go away over time?

Appreciate responses,
P
Patio Image

[Tony McC]

See the comments I made in response to Bob_A's post earlier today Granite Planks

Nothing you can do about it, this late in the game, I'm afraid.

[Bob_A]

Tony could it be that it's been laid on a bed of sand, perhaps the effect could've be lessened if it were laid on sand/cement and if so could an additive be added?
Edit
I'm not sure now as I've just read what you said about Trass bedding and reflective staining.

[Pissednbroke]

Thanks for the reply’s so essentially the backs of the slabs should have been sealed with primer prior to laying?
Does this get worse over time and gradually even out?
Thanks again

[Tony McC]

Over a few years (say 3-5) it does tend to even out as the granite pores 'clog' but there's no guarantee. Some of the more porous granites (and G603 was/is notorious for it) will keep showing damp patches for years and years - I've recently seen stone laid in 2005 that is *still* suffering from damp patches!

A primer coat can never provide a guarantee that damp patches definitely won't occur, but they will be far fewer and much harder to form when a good primer or slurry coat is used.