Help! need advice on moisture stains on paving.

[AAA10]

Hi, I recently (couple weeks ago) had some sawn sandstone paving installed, and have been having problems with what appears to be trained moisture stains. The paving was laid on a full bed of mortar (not spot bedded) so I'm struggling to understand what is causing it. Any pearls of wisdom are most welcome!

Thanks


http://s1052.photobucket.com/compone....e_3.jpg

http://s1052.photobucket.com/compone....e_3.jpg

[lutonlagerlout]

that looks tidy,but the joints are a little tight for my liking
why has it not been pointed?
some sort of moisture issue there but theoretically it should dry out ,sooner rather than later
looks a good job
LLL

[AAA10]

Thanks for the reply bud. I'm hoping your right, as with this heat wave I thought they would be dry by now! Should I avoid sealing until they clear up??

[seanandruby]

Yes let them dry completly.

[Tony McC]

There are two most likely causes. It could be either or it could be a bit of both.

First, it could be that the damp flags are slightly more porous than the dry flags and so are wicking/retaining moisture more readily.

Secondly, it could be that the bedding mix is different beneath the damp and the dry flags.

What strikes me is that it seems to be affecting whole flags (more or less) which suggests it's not something systemic but a variable which impacts on certain flags only. I know there is one flag that looks damp-ish but that could be a transition piece, halfway between the damp and the dry.

And those joints need sealing with summat otherwise they are just going to collect crap.

[AAA10]

There are two most likely causes. It could be either or it could be a bit of both.

First, it could be that the damp flags are slightly more porous than the dry flags and so are wicking/retaining moisture more readily.

Secondly, it could be that the bedding mix is different beneath the damp and the dry flags.

What strikes me is that it seems to be affecting whole flags (more or less) which suggests it's not something systemic but a variable which impacts on certain flags only. I know there is one flag that looks damp-ish but that could be a transition piece, halfway between the damp and the dry.

And those joints need sealing with summat otherwise they are just going to collect crap.

Thanks for the replies!

Yes I will get the joint filled, it had kiln dried sand in there, but it blew out when I pressure washed the slabs.

I'm fairly certain the guy used the same bedding mix all the way round. It's just bizarre how the pattern of patchiness is spread. It's not typical picture framing or spot bedding.

From what you guys are saying, it doesn't sound like it should be terminal, so I'm going to be patient and see if it dissipates over the next few weeks!

[Tony McC]

If you are going to be pressure washing this pavement regularly, then look to use a joint stabiliser with the KDS so that you don't lose the sand every time you clean.

[AAA10]

If you are going to be pressure washing this pavement regularly, then look to use a joint stabiliser with the KDS so that you don't lose the sand every time you clean.

Yes that's a good shout!